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2023-01-01 | The damping due to liquid viscosity and free surface contamination in the tuned liquid damper (TLD) is often insufficient to dissipate the vibrational energy that is transferred to the damper from the primary structure during their dynamic interaction. Installation of flow damping devices (FDDs) in the TLD can enhance its energy dissipation capacity manifold. FDDs are specially designed appendages that induce added damping by providing hydraulic resistance to the motion of the sloshing liquid. Among the available FDDs, slat screens and horizontal baffles are widely studied by researchers. A comparative study of the added damping provided by these two FDDs, along with their other advantages and disadvantages, is presented in this paper. Additional damping induced by the said FDDs is evaluated numerically considering a standard rectangular TLD configuration. | Enhanced Damping in a TLD by Slat Screens and Horizontal Baffles: A Comparative Study | 10.1007/978-981-19-3266-3_22 |
2023-01-01 | This chapter describes the basic theory of vibration. It starts with undamped single-degree-of-freedom (SDOF) systems in translation and torsion and equations of motion are derived. Various damping models used for dissipation of energy are described. Forced vibration equations without damping and with viscous and structural damping models are covered. The determination of damping ratio using the log decrement method and the half power method are explained. The response of SDOF systems with unbalanced forces and synchronous whirling of rotating shafts are discussed. Thereafter, force and displacement transmissibility have been explained. This is followed by a discussion of 2-degree-of-freedom systems with pure translation, as well as with coupled translation and rotation. A description of the undamped vibration absorber is presented. Free vibration of undamped and damped multi-degree-of-freedom systems is then discussed, followed by a discussion of orthogonality of normal modes. Free vibration equations of multi-degree-of-freedom (MDOF) systems in terms of modal coordinates are derived. Next, the response of an MDOF system to harmonic excitation is derived along with an introduction to the frequency response function (FRF). Finally, vibrations of continuous systems, namely longitudinal vibration of a rod and transverse vibration of an Euler-Bernoulli beam have been described. | Theory of Vibration | 10.1007/978-3-031-03968-3_2 |
2023-01-01 | Energy-bound forming machines such as forging hammers tend to vibrate due to abruptly applied process forces, which is particularly noticeable in form of intense vibrations of the machine environment. This paper presents a new concept of shock absorbers for forming machines, using dampers filled with magnetorheological fluids. Magnetorheological fluids are suspensions of magnetizable particles in a non-magnetizable carrier fluid. By applying a magnetic field, the internal structures and thus the rheological properties of the fluid can be varied. Using an evolutionary based control strategy, the damping can be adjusted depending on the excitation. The dependencies as well as challenges in the design process of magnetorheological dampers for forming machines are described. In addition, simulation results of foregoing studies concerning damper design and the evolutionary control strategy are presented. | Adaptable Press Foundation Using Magnetorheological Dampers | 10.1007/978-3-031-18318-8_36 |
2023-01-01 | Compared with the voltage source inverter, the current source inverter has the boosting characteristics, and the AC side does not need a complex and bulky filter unit, but it also has the problem of current control of the DC energy storage inductor. This paper studies the control strategy of a single-phase five-switch current source grid-connected inverter with a DC chopper. Firstly, hysteresis control is performed on the chopper to realize the constant output of the DC energy storage inductor current, which reduces the design difficulty of the grid-side current control system. Then, in view of the peak resonance problem of the LC filter, the active damping link of capacitor voltage is introduced, and the single closed-loop PR control parameters of the grid-side current are optimized in the case of considering the digital delay. Simulation results show that the system can ensure high power quality output and fast dynamic response, which proves the feasibility and effectiveness of the proposed control strategy. | Single-Phase Grid-Connected Current Source Inverter Based on Control of DC-Link Current | 10.1007/978-981-99-0631-4_111 |
2023-01-01 | In recent studies, laser powder bed fusion (LPBF) additive manufacturing has created structural beam components possessing internal pockets containing unfused metallic powder. Compared to fully fused beams, these pocketed beams have demonstrated a remarkable improvement in damping performance, suppressing vibrations by as much as 95%. This suggests that internal geometries containing unfused powder can be a significant design feature to reduce vibration and extend the life of structural components. However, additional studies and improvements are needed before these designs can become widespread. For example, it has been observed that the unfused powder begins to fuse to the walls of the pockets when subjected to high strain loading, reducing their damping abilities. This study investigates the effects of the thickness of the beams and the pocket’s axial location in LPBF nickel-based alloy 718 beams on their damping sustainability after being subjected to high strain loads. The beams are subjected to successive resonance dwells with increasing strain amplitude. After each dwell, the damping performance is assessed via frequency sweeps. Results from this study indicate that the decrease in damping performance follows the same relative trend regardless of the beam thickness. The axial location of the pockets affects the initial damping and also influences when the powder begins to fuse. | Effects of Internal Particle Damper Thickness and Location on Damping Sustainability of Additively Manufactured Nickel Alloy Beams | 10.1007/978-3-031-17453-7_10 |
2023-01-01 | Metastructures, a metamaterial-type structure designed with distributed vibration absorbers, are a growing development in the area of passive vibration suppression. Previous research has shown that it is possible for vibration absorbers to be introduced into a structure for broadband vibration suppression without introducing additional mass. The proposed mass-conserved metastructures are modeled using lumped parameter and finite element approaches and are compared to a baseline structure of equal mass to quantify the level of vibration suppression achievable for each metastructure. The objective of this work is to experimentally verify the lumped parameter model of mass-conserved metastructures. This work chooses to focus on the lumped parameter model due to its simplicity and potential application to other metastructure designs. A baseline structure and two metastructure designs are considered in the analysis, and a 3D printer was used to create the metastructures which were then subject to vibration testing. The effectiveness of the vibration suppression will be analyzed using the steady-state and transient responses. The experimental results of the 3D printed metastructures show a similar response to the 1D lumped parameter metastructure model, indicating that a level of vibration suppression can be achieved without adding additional mass to the structure. | Experimental Verification of 1D Lumped Parameter Model of Mass-Conserved Metastructure | 10.1007/978-3-031-05445-7_17 |
2023-01-01 | Damping of vibration is an effective approach mostly utilized in mechanical systems to control and reduce excess vibrations. Vibrational energy is dissipated due to impact, energy exchange, and friction between the gear body and the impact mass (particles). Hence, particle impact damping techniques are employed in engineering systems such as gearboxes to reduce unwanted vibration. The goal of this research is to visualize experimental gearbox vibration data to examine the influence of particle damping under various conditions like applied load, particle filling rate, particle size, number of holes, healthy, and faulty. Then, it was explored and verified by the experimental and Tableau platform. The study is limited to consideration of particle damping and its effect for reducing vibration only. This paper attempts to investigate the effect of particle damping to find the most sensitive damping combination with considerations by varying the conditions like load, particle filling rate, ball diameter, no. of holes, and gear condition for the gearbox system under consideration. Analysis of this study by using Tableau platform for visualization of vibration data to show that effect of damping with relation to load is carried out. The new approach is developed, with the result being the damping of gear vibrations utilizing the particle method, which helps to suppress vibrations. As the increase in the size of the particle, then chances of getting a more damping effect with a size of 5 mm for the steel particles showed good damping with keeping the applied load constant. | Data Visualization of Vibration in the Gearbox to Study Particle Damping Using Tableau Platform | 10.1007/978-981-19-6945-4_80 |
2023-01-01 | This chapter deals with two case studies in which waste tires were used to protect embankments. The first one is related to a series of forensic and laboratory investigations of an existing retain wall made of tires, which did not suffer any damage neither by earthquake nor by tsunami during the 2011 Off the Pacific Coast of Tohoku Earthquake, Japan. The second one is related to the field trial and laboratory investigation on the use of tire shreds, a granular material derived from waste tires, to enhance the drainage in a highway embankment. | Applications of Waste Tires for Protection of Embankments in Northern and Northeastern Japan | 10.1007/978-981-19-3322-6_10 |
2023-01-01 | Under cyclic fatigue loading, cyclic-dependent damage mechanisms affected the vibration damping of fiber-reinforced ceramic-matrix composites (CMCs). In this chapter, a cyclic-dependent vibration damping model of fiber-reinforced CMCs was developed. Combining cyclic-dependent damage mechanisms, damage models, and dissipated energy model, relationships between composite vibration damping, cyclic-dependent damage mechanisms, vibration stress, and applied cycle number were established. Effects of material properties and damage state on composite vibration damping were analyzed for different applied cycle number and vibration stress. Experimental composite vibration damping of 2D and 3D C/SiC composites without/with coating was predicted for different vibration frequencies and applied cycle number. | Cyclic-Dependent Vibration Damping of Ceramic-Matrix Composites | 10.1007/978-981-19-7838-8_6 |
2023-01-01 | Seismic isolation has become increasingly popular due to the excellent performance observed in buildings during past earthquakes. The seismic response of isolated structures to earthquake input is strongly controlled by the force-deformation constitutive behavior of the isolators. High Damping Rubber Bearings (HDRBs) are one of the most widely manufactured and used isolation systems in practice. Because of the large shear flexibility, the stress-strain constitutive behavior of the elastomeric material controls the overall behavior of the device. Thus, the behavior of HDRBs is highly nonlinear and characterized by the same phenomena as the elastomeric material, which is challenging to model analytically. Consequently, this article describes a simple but sufficiently accurate numerical model for simulating the bi-directional shear behavior of HDRBs under large shear deformations. A brief description of the experimental test data of HDRBs is presented, as well as the importance of including the observed phenomena in the numerical model proposed. The mathematical formulation of the proposed model is summarized, based on a hyperelastic spring and dissipative element connected in parallel. The former considers anisotropic degradation (scragging and Mullins effect), while the latter includes the isotropic hardening phenomenon. The proposed model was validated using experimental results of bi-directional shear tests of cylindrical disks of high damping natural rubber, unidirectional shear cyclic tests, and a bi-directional shear loading history applied to an HDRBs. Since the proposed model is capable of simulating the bi-directional cyclic behavior of HDRBs by considering anisotropic degradation instead of the classical isotropic behavior, which improves the numerical predictions, it can be used in dynamic analyses of buildings isolated with HDRBs. | Bidirectional Model for Shear Behavior of High Damping Rubber Bearings | 10.1007/978-3-031-21187-4_13 |
2023-01-01 | This chapter gives a general introduction to three-wave instabilities in plasmas. It provides a simple physical picture of instabilities, and a full list of all three-wave instabilities that can occur in plasmas (each of which will be described in more detail in Chaps. 7 , 8 , and 10 ). It provides the main tools used to describe instabilities, starting with the coupled wave equations, and introduces key metrics such as the growth rate, the spatial amplification rate, and the amplification in non-uniform plasmas with a derivation of the well-known “Rosenbluth gain” formula. The last section presents a more comprehensive treatment of instabilities via the Green’s function of the coupled mode equations; this approach provides a simple and intuitive introduction to the concepts of absolute vs. convective instabilities and the derivation of their associated thresholds and growth rates. | Introduction to Three-Wave Instabilities | 10.1007/978-3-031-23424-8_6 |
2023-01-01 | In the dynamics of a non-ideal anisotropic gyroscopic rigid rotor, the Sommerfeld effects and the effect of linear and nonlinear cubic damping on them are investigated. The equations of motion based on the second kind Lagrangian equations are solved by the method of small perturbation theory, resulting in non-stationary vibration equations and the governing equation in relation to the stationary amplitude and phase-frequency characteristics of the rotor. A comparative analysis of the speed characteristics of the system shows that an increase in nonlinear cubic damping at a constant value of linear damping can lead to the disappearance of an unstable branch in the first resonant region, a significant decrease in the size of the jump in the speed of rotation of the shaft in the second resonant region. A further increase in the non-linear cubic damping value can practically eliminate the Sommerfeld jump effect. It is proven by the power control characteristic of the system that the larger the damping effect, the less power the drive will need to smoothly transition through the critical velocity regions. Amplification of nonlinear cubic damping in the presence of constant linear damping is an effective model of optimal damping for a smooth transition of resonances. | The Sommerfeld Effect in a Non-ideal Anisotropic Gyroscopic Rotor System and the Effect of Nonlinear Damping | 10.1007/978-3-031-45705-0_82 |
2023-01-01 | This paper reports a comparative influence of the two different types of loading mechanisms on the frequency-dependent dynamic properties of the cohesionless Brahmaputra sandy soil. The shear modulus and damping ratio of the chosen soil are largely influenced by the loading frequencies of the two different testing types. Based on the strain-controlled and stress-controlled loading conditions, the loading frequency is found to influence the shear modulus and damping ratio with a contradicting response between the parameters. In case of strain-controlled tests, the damping ratio increases with a loading frequency of up to 1 Hz followed by a decrement for higher frequencies; while for stress-controlled testing, the shear modulus increases up to a loading frequency of 1 Hz followed by a decrement for higher frequencies. Further, it can be stated that, during strain-controlled loading, the frequency of loading is found to influence significantly the damping ratio only, whereas for stress-controlled loading, both the damping ratio and shear modulus are found to be affected significantly by the loading frequency. | Frequency-dependent Dynamic Properties of Saturated Brahmaputra River Sand Based on Cyclic Triaxial Tests | 10.1007/978-981-99-0081-7_6 |
2023-01-01 | The slug flow is one of the most complex flow patterns due to the unstable behavior of phase distribution. This pattern occurs in a wide range of flow rates and therefore is observed in different industrial processes. The prediction and understanding of the hydrodynamic parameters of this flow regime have a significant engineering value. In this context, Computational Fluid Dynamics (CFD) has been shown to be an efficient tool for the prediction of this type of flow. However, to ensure the accuracy of the numerical solution, adequate modeling of interfacial properties transfer is necessary. One of the most important interface transfer phenomena is momentum transfer between phases. Therefore, it is necessary to use a robust approach to model the gas–liquid interface region. The aim of this study is to evaluate the effect of adding the damping of turbulent diffusion at the interface on flow modeling. For this, different cases of simulations were elaborated for a pipe with 2 m in length and 26 mm inner diameter. In all the cases, the multiphase approach used was the Volume of Fluid (VOF) with the Geo-Reconstruct scheme. The interface between the fluids was modeled with constant surface tension equal to 0.0728 N/m. The discontinuities present at the interface were treated in a “continuous surface stress” (CSS) manner. The turbulence was modeled using kω-SST with and without turbulence damping. The independence of the numerical solution in relation to the grid was evaluated by the Grid Convergence Index (GCI) method in which four levels of grid were used. Preliminary results showed that, in the cases with turbulence damping, a better representation of the flow pattern morphology was obtained. Regarding the quantitative parameters, the prominent frequency of the Power Spectral Density (PSD) of the pressure signal was under-predicted when the turbulence damping was not used. | The Turbulence Damping Effect on the Slug Flow Modeling | 10.1007/978-3-031-25990-6_2 |
2023-01-01 | Although the detrimental effects of the low temperature condition on the seismic performance of High Damping Rubber (HDR) bearings are known by the past studies, influence on the dynamic response of structural systems with HDR bearing application and evaluation of consequent seismic performance reduction are yet to be explored. In this research, hybrid simulation for HDR bearings’ seismic isolation effectiveness assessment in cold regions was conducted. The testing equipment for elastomeric bearing specimens was modified to enable low-temperature shear loading test under axial load. Shear modulus variation of HDR at different ambient temperatures is shown to diminish as the cyclic loading to HDR bearing progresses, presumably due to the self-heating effect caused by the energy dissipation, as demonstrated by preliminary cyclic loading tests. The effects of low ambient temperature on the dynamic response of the isolated bridge are observed in terms of the increased maximum shear strain of the HDR bearing, amplified maximum load acting on the bridge piers during the seismic excitation, and the consequent increase of pier top displacement. | Hybrid Simulation for Seismic Isolation Effectiveness Assessment of HDR Bearings at Low Temperature | 10.1007/978-3-030-93236-7_26 |
2023-01-01 | Here we present an analysis of dynamic errors which occurs in mechanical systems of weighers, equipped by a quadrant balancing mechanism as a function of time, when the weighing system moves freely while materials are shocklessly loaded into the hopper. This article considers the mechanical system of dispensers, discussing technological features and disturbing effects on the dosing process. Our findings indicate significant oscillation of the batcher weighing system during the loading process, determining the ways of increasing the dosing accuracy and explaining the fundamentals of the arrow movement of the quadrant dial pointer while loading the hopper. The dynamics of the balancing mechanism of the weighing mechanical lever system of the batcher is based on the equation of free vibrations and the oscillatory motion of the dispenser weighing system is determined by Rayleigh formulas. Expressions for movement of the dispenser weighing system and dynamic error are obtained. Taking into account the construction of the weighing system of the dispenser used in the production of concrete mixtures, the frequency of natural oscillations of the mechanical system was calculated.Results are obtained for the dynamic dosing error in the case of undamped movement of the weighing system and in the case of viscous critical damping. | Mathematical Model of the Dynamics of the Balancing Mechanism of the Weighing System of the Batcher | 10.1007/978-3-031-14125-6_37 |
2023-01-01 | One of the renewable energy devices in development is the oscillating water column (OWC) which utilizes the movement of ocean waves on a partly immersed section consisting of air–water subsections to harvest ocean wave energy. Several critical parameters such as pressure and free surface velocity, along with free surface elevation control the efficiency of OWC. In presented work, a study is carried out in ANSYS Fluent Solver. For generating wave in a NWT., Stokes 5^th order wave theory is applied (Michael Horko (2007) CFD optimization of an Oscillating Water Column Wave Energy Converter. M.S. Thesis, The University of Western Australia. s.l.:s.n.). A porous media is used for pressure generation and damping. The effects of power take-off damping are observed during the simulations. A good agreement in simulation results can be seen with Kamath et al. and Thomas et al., which are validated. Further, this study aims to increase the efficiency of OWC. This paper provides a numerical analysis for modified upper OWC chamber shape and four vertical plates inside the chamber. Simulation results signify the improved peak efficiency to 90.27% from 66.5% and average efficiency to 40.75% from 28.89% in the modified models. | Numerical Validation of Power Take-Off Damping in An Owc Chamber and Modifications for Increased Efficiency | 10.1007/978-981-19-3379-0_32 |
2023-01-01 | Roll damping is probably the most intriguing of the components of hydrodynamic reaction in ship dynamics. It is also a problematic one—small, nonlinear, difficult to measure or predict and crucially, a key determinant of ship stability. Undoubtedly, some of the problems in computing or predicting roll damping are intrinsic. It can be argued, however, that most of the difficulties do not originate from physical anomalies of energy dissipation in roll but are due to fundamental flaws in the approach to roll damping estimation or measurement. It appears that the root causes of these flaws stem from three concepts central to analysis of hydrodynamic reaction in roll: decomposition of the hydrodynamic reaction moment to added moment of inertia and roll damping moment, the assumption of small-amplitude motions, and the inevitable coupling of roll with other modes of motion. In this paper, the authors present a pragmatic approach to these fundamental concepts and discuss the implication of incorrect assumptions, pertaining to definition, measurement, calculation and use of roll damping in intact and damaged ship dynamics. | A Pragmatic Approach to Roll Damping | 10.1007/978-3-031-16329-6_30 |
2023-01-01 | The manuscript is based on a talk given by the author in a workshop of Control & Inverse problems in Monastir from May 9 to May 11, 2022. This note is an invitation to the microlocal method for the wave stabilization problem, with particular emphasis on the result by Sun (Sharp decay rate for the damped wave equations with convex-shaped damping, in International Mathematics Research Notices , vol. 2023(7) (2023), pp. 5905–5973. https://doi.org/10.1093/imrn/rnac022 ) for the damped wave equation on the two-dimensional flat torus. The author would like to thank Kaïs Ammari for the invitation to present this proceeding article. | Revisit the Damped Wave Equation | 10.1007/978-3-031-35675-9_14 |
2023-01-01 | This work is the next of a series on vibrations of non-homogeneous structures. It addresses the lateral harmonic forcing, with spatial dependencies, of a two-segment damped Timoshenko beam. In the series, frequency response functions (FRFs) were determined for segmented structures, such as rods and beams, using analytic and numerical approaches. These structures are composed of stacked cells, which are made of different materials and may have different geometric properties. The goal is the determination of frequency response functions (FRFs). Two approaches are employed. The first approach uses displacement differential equations for each segment, where boundary and interface continuity conditions are used to determine the constants involved in the solutions. Then the response, as a function of forcing frequency, can be obtained. This procedure is unwieldy, and determining particular integrals can become difficult for arbitrary spatial variations. The second approach uses logistic functions to model segment discontinuities. The result is a system of partial differential equations with variable coefficients. Numerical solutions are developed with the aid of MAPLE® software. For free/fixed boundary conditions, spatially constant force, and viscous damping, excellent agreement is found between the methods. The numerical approach is then used to obtain FRFs for cases including spatially varying load. | Forced Vibrations of Damped Non-homogeneous Timoshenko Beams | 10.1007/978-3-031-05415-0_2 |
2023-01-01 | Particle impact damper (PID) is an emerging passive damping technology with significant advantages over other passive damping systems. It is not commonly used in practice because of its low damping rate compared to the common viscous damper. Owing to various nonlinear phenomena present in the impact damping process, the analytical methods for design optimization of PID are rarely found. It is observed that the particle impact damper has two phases of damping when it is applied to a single-degree-of-freedom (SDOF) vibration system. In the first damping phase of the PID, there is significant damping with many strong head-on collisions in the PID. On the other hand, the second damping phase begins when the vibration amplitude of the primary system is reduced to a certain level and negligible damping of the PID is observed in this phase of long duration with only a few ineffective impacts in the PID. To improve the overall damping rate of the PID, it is proposed to combine the PID with a small external friction damper (FD) to reduce the duration of the ineffective damping phase of the PID in the free vibration of the primary system. A numerical model is established for the proposed hybrid damper and it is validated by experiments. The numerical model can simulate the response of the primary system with the proposed hybrid damper over a wide range of design parameters and an optimal design combination can be determined. It is shown by both numerical and experimental results that the proposed hybrid damper can improve the damping performance significantly and provides robust damping in free vibrations of SDOF systems. | A Hybrid Damper with Particle Impact Damper and Coulomb Friction Designed for Free Vibration Damping | 10.1007/978-3-031-39109-5_56 |
2023-01-01 | It has been known that the hysteretic behavior of High Damping Rubber (HDR) bearings is significantly affected by low ambient temperature, while the restoring force gradually reduces under repeated cyclic loading due to self-heating of the rubber material. For seismic response simulation of isolated bridges in cold regions for earthquake events occurring in winter, a nonlinear hysteresis model of HDR bearing with consideration of the thermo-mechanical coupling is necessary for realistic seismic safety assessment of the bridge isolated with HDR bearings. In this study, a thermo-mechanical coupled hysteretic restoring force model of HDR bearing is developed based on the bilinear model. The model is combined with a procedure to estimate the instantaneous inner temperature of the bearing using the information of the hysteretic energy dissipation and heat conduction/radiation, and the mechanical properties of the bearing are updated according to the inner temperature information. The model parameters are identified from quasi-static loading tests of HDR bearing specimens under various ambient temperatures, and the validity of the developed model is discussed based on a comparison of the result of numerical dynamic simulation of a bridge model using HDR bearings subjected to design ground motion with the experimental result obtained by hybrid simulation of the same bridge model using a test system that allows shear loading of HDR bearings under low ambient temperatures. | A Thermo-Mechanical Coupled Model of Hysteresis Behavior of HDR Bearings | 10.1007/978-3-030-93236-7_27 |
2023-01-01 | Although being rarely categorised as “smart”, bulk materials seem to be useful for attenuating vibrations due to their nontypical dissipating properties, when subjected to underpressure. Granules in a typical particle impactor are free to move and collide. On the contrary, the proposed prototype beam, with a core filled with dilatant sand, explores the properties of the granular media in a quasi-solid phase, also called the jammed state. Using a controlled underpressure signal, properties of the sand core may be adjusted, giving a possibility of using such material as a smart damping member. An experimental study on the properties of a prototype layered beam filled with a non-Newtonian sand mixture is presented. Special beam construction allows pressurising grains by evacuating the air from inside the cover. By intensifying the compression, sand grains become jammed, resulting in increased stiffness and damping. Based on the exemplary experimental results, a custom rheological model parameter identification is performed. | Rheological Model and Parameter Identification of a Kinetic Sand Used as a Smart Damping Material | 10.1007/978-3-030-93236-7_54 |
2023-01-01 | Modern hydraulic shock absorbers display a wealth of nonlinear effects such as hysteresis and instabilities at high flow rates. Despite their wide application in practically all vehicles, both on- and off-road, a universal analytical model that captures the essential shock absorber dynamics and compressibility effects for various common damper architectures is lacking. This paper presents such a model and derives its system of equations from first principles for dampers of monotube- and piggyback-type. By applying the model to a typical suspension configuration, all relevant system variables, such as pressure drop, shim stack deflection, and damping force, are computed. Nonlinear oscillations and hysteresis loops, which might prove dangerous during operation, can be predicted effortlessly. The results achieved with the mathematical model are validated and agree well with test bench measurements. Furthermore, the presented approach is shown to be easily modifiable to describe the physical processes within other hydraulic shock absorber geometries in use today. | A universal nonlinear model for the dynamic behaviour of shock absorbers | 10.1007/s11071-022-07896-4 |
2023-01-01 | In this chapter, a review of the optimum design of passive and active tuned mass dampers for structures is presented. Metaheuristics have been often used in the optimum design of tuned mass dampers. As an example, an improved harmony search algorithm is presented for the optimum design of active tuned mass dampers (ATMDs) using proportional integral derivative type controllers. The ATMD was also compared via passive tuned mass damper (TMD) and the optimum design results are presented for a 10-story structure with multiple cases of the time delay of the controller and stroke capacity of ATMD. ATMD is better than TMD in the reduction of displacements up to 32.01%. | Review of Tuning Mass Dampers and Application of Improved Harmony Search | 10.1007/978-981-99-2378-6_1 |
2023-01-01 | In the present paper, the problem on numerical dynamic simulation of bending structural elements made of orthotropic materials, such as composites and nanomaterials, is considered. The modeling of damping properties of such materials, including those that are initiated by internal friction in the material, is of particular concern. Damping parameters of the proposed numerical model are nonlocal in time. Such a model provides the results allowing one to approximate enough reliably the dissipative properties of constructional elements made of composite materials. The nonlocal in time damping model, known as “damping with memory”, is embedded into the finite element method algorithm. An equilibrium equation for a beam element in motion is solved numerically utilizing an implicit scheme. The damping matrix for the proposed model is derived from the condition of stationarity of the total deformation energy of the moving mechanical system. The provided analysis of the one-dimensional nonlocal in time design model has shown that the modified implicit scheme allows one to increase the accuracy of the experimental data approximation. | A Modified Implicit Scheme for the Numerical Dynamic Analysis of Beam Elements Considering Nonlocal in Time Internal Damping | 10.1007/978-3-031-21120-1_22 |
2023-01-01 | This contribution introduces a one-mass oscillator subject to passive and active vibration isolation. In this context, passive means that the vibration isolation behavior only depends on preset inertia, damping, and stiffness properties. Active means that additional controlled forces change and adapt the damping properties to enhance the vibration isolation behavior. The purpose of the system is, eventually, to assess diverse measures in quantifying model form uncertainty of various mathematical models of the passive and active vibration isolation configuration in a consistent and comparable way. On the one hand, the one-mass oscillator is simple enough to be modeled analytically to establish a reference model. With its realization as an experimental test environment, it also allows more complex models such as a two-mass oscillator, which is still modeled analytically, and numerical finite and multi-body modeling. The test environment guarantees a consistent and comparable discussion about different approaches to quantify model form uncertainty in an uppermost comprehensive and extended way. First, the author derives the mathematical model for numerical simulation and explains the real test environment. An impulse excites the mass, and the mass responds with vibrations, given by velocity and acceleration responses. Second, preliminary studies for different passive and active damping cases identify the differences between numerical and experimental outcomes from simulation and test. The contribution closes with an invitation to continue and extend the work by a round robin within IMAC’s Model Validation and Uncertainty Quantification MVUQ community. | Comprehensive Testing Environment to Evaluate Approaches in Uncertainty Quantification for Passive and Active Vibration Isolation | 10.1007/978-3-031-04090-0_11 |
2023-01-01 | This paper proposes a novel hybrid tuned mass damper (TMD) and tuned liquid damper (TLD) system (TMD + TLD) for vibration control of multi-degree of freedom structures under seismic excitations. The proposed system is introduced using equations of motions of a five-degree of freedom structure which is modeled as a shear-type with a lateral degree of freedom at each floor under harmonic and earthquake excitations. The proposed hybrid TMD + TLD system is introduced to the building structure in the model. Several case studies are investigated to evaluate the performance of the proposed system. In the first case, both TMD and TLD are tuned to the first frequency of the structure, and the TMD is fixed to the top floor, and the TLD is fitted to the fourth floor of the primary structure. In the second case, the TMD is tuned to the first frequency of the structure, whereas the TLD is tuned to the second frequency of the structure. All the cases are investigated under harmonic force and real earthquake ground motions. The earthquakes selected in this study are classified as low, intermediate, and high-frequency content earthquakes. Results indicated that with comparatively less mass ratio, the earthquake-induced structural vibration is successfully suppressed when the TMD is tuned to the 1st frequency, and the TLD is tuned to the 2nd frequency of the structure. The focus of the investigation is to develop a practical framework to demonstrate the efficiency of such a hybrid damper. | Seismic resilience enhancement of MDOF systems utilizing a hybrid TMD-TLD | 10.1007/s10518-022-01531-8 |
2023-01-01 | The modern maritime industry is moving toward the development of technology that will allow for full or partial autonomy of ship operation. This innovation places high demands on ship performance prediction techniques at the design stage. The research work presented in the article is related to the design stage of the ship and concerns methods for prognosis and evaluation of the specific operational condition of the ship, namely the dynamic positioning (DP). The paper is an introduction to a study that seeks to assess the impact of using advanced simulation models on the accuracy of DP capability prediction. To this end, the Potential Theory and methods of Computational Fluid Dynamics (CFD) are applied to determine the mathematical model of the ship. The parameters obtained in the course of simulation studies have been compared to those obtained experimentally. The study showed that the proposed method is sufficiently accurate for the purposes of determining the added mass and damping coefficients of the ship. Consequently, it is considered that design offices could improve the accuracy of the DP prediction by using mathematical modeling and numerical methods to estimate selected ship parameters. | Identification of Ship’s Hull Mathematical Model with Numerical Methods | 10.1007/978-3-031-35173-0_31 |
2023-01-01 | To fulfill the high requirement of safety and comfort in automobiles, many new technologies are applied in suspension system. Damper acts an important role in suspension system for eliminating vibration. Bingham model of magneto-rheological (MR) damper is proposed for obtaining the control forces. In this work, proportional integral derivative (PID) controller gain parameters are adapted by the output parameters of fuzzy logic control to regulate the damper in the suspension system. The vehicle body deflections for two different road profiles are chosen for the performance analysis of fuzzy tuned PID controller and only PID controller. On the basis of simulation results, it is observed that fuzzy logic-based PID controller displays more improvement in efficiency and comfort level of riders by decreasing the amplitude of the vibration as compared to PID controller. | Fuzzy Logic-Based PID Controller Design for Car Suspension System with Magneto-Rheological Damper | 10.1007/978-981-19-7709-1_9 |
2023-01-01 | The level of the vibrations and the presence of instability are the two most critical aspects regarding the operations of turbomachinery. To cope with this issues that may compromise the operation of the machines, squeeze film dampers (SFD) are often used in many industrial applications. Unfortunately, many complex phenomena characterize the dynamic behavior of these components and determine the high complexity of the modeling of these components. The most relevant phenomena involved in the characterization of SFDs are individuated after a comprehensive investigation of the state of the art. Among them, the oil film cavitation, the air ingestion, and the effect of the inertia are introduced. A modeling strategy based on the Reynolds equation is then presented. The boundary conditions to be adopted for the feeding and discharging of oil are investigated and implemented. Eventually, the finite difference model is applied to a practical example to evaluate the possibility to minimize the vibration level and to reduce the effect of the instability if a SFD is added to a rotodynamic system. Meaningful information about the modeling of SFDs is provided in this work. The critical aspects of these components and their modeling are highlighted and discussed. | Application of Squeeze Film Dampers | 10.1007/978-3-031-32394-2_8 |
2023-01-01 | These days the power framework is vigorously stacked, because of the steady interest for power which causes shakiness. There might be lacking and successful energy. This paper discloses the appropriate method for making up for the productive and successful power and decreases the motions in the multi-machine framework with four machines and six transport devices. The Static Synchronous Series Compensator (SSSC) can be contemplated as the main remuneration for the series utilized by the FACT family in transmission frameworks. This paper has examined the mistake of three stages. Reenactment is accomplished in the MATLAB/SIMULINK programming program in four cases: test the gadget without mistake, with issue, with the SSSC without control, and SSSC with Power Oscillation Damper (POD). The recreation result shows that without SSSC, the framework becomes temperamental during blunders. While the SSSC is feeling the squeeze inside the organization, the framework will settle. Inside the case, while the SSSC has a POD, then, at that point, the framework boundaries will be significantly more vigorous in a quicker way than without a regulator. So with POD, the entire machine execution is significantly refined and the power framework motions are delivered rapidly. | Enhancement of Power System Stability and Damping Oscillation in a Multi-Machine System Using SSSC | 10.1007/978-981-19-2764-5_24 |
2023-01-01 | The active power-frequency control of the traditional virtual synchronous generator (VSG) will produce out power error from the droop control due to the introduction of damping, so VSG would not meet the requirements of dynamic active power damping and the primary frequency modulation of the power grid at the same time. By analyzing the principles of VSG control, the virtual synchronous control strategy is applied to the modular multilevel converter (MMC), and the VSG control strategy is improved, and a high-pass filter is introduced into the damping loop, and the damping loop signal is set to zero when the system is stable, thus active power deviation due to introduced damping is eliminated. The optimal control strategy can dynamically adjust the damping coefficient to ensure the necessary damping of the power system and increase the effectiveness of the droop control. Finally, the feasibility and effectiveness of the improving strategy are verified by MATLAB/Simulink simulation. | Research on Optimal Control Strategy of VSG Damping Loop Based on MMC | 10.1007/978-981-99-1439-5_7 |
2023-01-01 | Automobile suspension has moving structural elements interconnected by elastic links. Oscillatory processes in the suspension of a vehicle occur when the wheels interact with the road. Depending on the speed of the vehicle, the frequency of vertical vibrations of the moving masses of the suspension also changes. Any mechanical system containing moving masses interconnected by elastic components has its own oscillation frequency. The phenomenon of resonance in the suspension of the vehicle occurs, when the frequency of external influences becomes equal to the natural frequency of vibrations. When the frequency of external sources becomes equal to the frequency of natural oscillations, a resonance phenomenon occurs. At resonance, the amplitude of oscillations increases sharply, which in turn causes vibration throughout vehicle’s body. This leads to a sharp increase in dynamic loads, which can lead to structural failure due to metal fatigue. The rigidity of the road tyre has a great influence on the oscillatory processes in the suspension of an automobile as it forms a single elastic system in conjunction with other elastic elements. To study resonance phenomena, a mathematical model of an automobile suspension has been developed. Based on the results of the numerical model, it has been determined that the structural resonance occurs at certain speeds. A method for dynamic damping of vehicle suspension vibrations at resonance is proposed. The effect of the road tyre stiffness and viscous friction in the shock absorber on the dynamic loads acting on the suspension elements has been established. For the vehicle suspension, the parameters of the dynamic vibration damper are determined. | Resonance Phenomena in Vehicle Suspension | 10.1007/978-3-031-38126-3_63 |
2023-01-01 | Hammer foundation is a system commonly used in engineering works and consists of a foundation system on which an anvil is housed and on the anvil a ram is allowed to fall from a specified height in controlled manner for stamping works. The present design procedure for hammer foundation (IS 2974-Part 2: Foundations for impact type machines (hammer foundations), Bureau of Indian Standards, New Delhi, 1980) assumes the hammer foundation to rest on semi-infinite, elastic soil body without any embedment. For industrial requirement, the amplitude of motion of the foundation is required to be maintained at a permissible limit value for the safe working condition and to keep propagation of vibration under control to adjoining structure. In the present design procedure, damping of foundation soil media has not been taken into account and since such damping has an influence on the response of foundation vibration in vertical mode, it is understood that the damping of foundation soil will effectively decrease the mass of needed foundation to cause specified vertical vibration amplitude. Furthermore, the damping factor at the site can be easily obtained from same block vibration test suggested for determining coefficient of uniform elastic compression ( C _U) of the soil at the site (IS 5249-Part 2: Determination of dynamic properties of soil—method of test, Bureau of Indian Standards, New Delhi, 1992). This paper analyses the effect of damping and compare the foundation masses required for a permissible value of amplitude of 1 mm set by IS: 2974, Part-2: 1980, for different possible foundation setup required for a particular fall and weight of ram. It is observed that the inclusion of damping characteristics of the foundation soil at the site would decrease the needed mass of the foundation for the hammer for chosen condition and thus lead to more cost effective design in practice. | Role of Damping in Response of Hammer Foundation | 10.1007/978-981-19-6998-0_48 |
2023-01-01 | Railroad train is an important transportation for modern travelling. In order to provide convenience for passengers, in particular for people who are disabled or carry large luggage, a hydraulic height adjustment system was designed. This system is equipped in the secondary suspension system to raise up or draw down carriages to fit in with platforms of different heights. According to the case of the changes to the vertical secondary suspension, four operating stages of the height adjustment system are decided. To verify dynamic performance of the system, a model was developed in AMESim. Results of simulation demonstrates its practicability, and the action time is less than 7 s. The effect of damping after height adjustment system is added to the initial secondary suspension system is also discussed. Based on the premise that passengers have a comfortable experience on the train, suggestions about the selection of pipe length, pipe diameter and oil temperature are put to ensure appropriate damping ratio. The research provides theoretical basis of subsequent application and optimization of the hydraulic height adjustment system. | Design and Simulation of the Hydraulic System for Height Adjustment of Carriages | 10.1007/978-981-99-6847-3_6 |
2023-01-01 | In IoT, energy dissipation reduction is an essential requirement for achieving high-performance sensors and communication devices. Among the various energy dissipations that limit the performance of IoT devices, thermoelastic energy dissipation is a crucial one which seems to be laborious to control. In thermoelastic damping (TED), due to the coupling between temperature and strain fields in the vibrating structures, irreversible energy dissipation occurs. In this paper, the energy dissipation of a cantilever-type micro/nanobeam resonator at high temperature is analysed and found to be increased as the temperature elevates. Consequently, to reduce thermoelastic energy dissipation $$\left( {Q^{ - 1} } \right)$$ Q - 1 at high temperatures, nonzero values for dimensionless length scale parameter are chosen and verified to be effective at all temperatures. The analysis is conducted by MATLAB 2015 and five diverse structural materials (Si, polySi, GaAs, diamond and SiC) are selected. The thermoelastic energy losses of micro/nanobeams are plotted by varying the temperature from 0 to 500 K. The increase in energy losses at elevated temperatures is minimised by the inclusion of the nonzero dimensionless length scale parameters. | Thermoelastic Energy Dissipation Trimming at High Temperatures in Cantilever Microbeam Sensors for IoT Applications | 10.1007/978-981-99-2322-9_19 |
2023-01-01 | A nonlocal study of the vibration responses of functionally graded (FG) beams supported by a viscoelastic Winkler-Pasternak foundation is presented. The damping responses of both the Winkler and Pasternak layers of the foundation are considered in the formulation, which were not considered in most literature on this subject, and the bending deformation of the beams and the elastic and damping responses of the foundation as nonlocal by uniting the equivalently differential formulation of well-posed strain-driven ( ε -D) and stress-driven ( σ -D) two-phase local/nonlocal integral models with constitutive constraints are comprehensively considered, which can address both the stiffness softening and toughing effects due to scale reduction. The generalized differential quadrature method (GDQM) is used to solve the complex eigenvalue problem. After verifying the solution procedure, a series of benchmark results for the vibration frequency of different bounded FG beams supported by the foundation are obtained. Subsequently, the effects of the nonlocality of the foundation on the undamped/damping vibration frequency of the beams are examined. | Unified two-phase nonlocal formulation for vibration of functionally graded beams resting on nonlocal viscoelastic Winkler-Pasternak foundation | 10.1007/s10483-023-2948-9 |
2023-01-01 | Using the kinetic theory approach, a theoretical investigation has been made to study the electron acoustic waves (EAWs) in non-thermal plasma. The dispersion relation $$\omega _{r}$$ ω r and Landau damping rate $$\gamma $$ γ for Langmuir waves (LWs) and electron acoustic waves (EAWs) are derived in a three component (ions, cold electrons and hot electrons) plasma, characterized by non-thermal Cairn’s distribution function. Analytical expressions show that the real frequency $$\omega _{r}$$ ω r and Landau damping rate $$\gamma $$ γ are strongly influenced by non-thermal parameter $$\alpha $$ α , hot to cold electron temperature ratio $$T_{h}/T_{c}$$ T h / T c and by the population ratio of hot to cold electron $$n_{0h}/n_{0c}$$ n 0 h / n 0 c . Furthermore, in the absence of non-thermal particles the well-known Maxwellian results are retrieved. For illustration the present model has been applied to space and astrophysical plasma such as: geomagnetic tail, cusp of the magnetosphere and the dayside auroral acceleration region where the cold and hot electrons population exist. | The Study of Electron Acoustic Waves (EAWs) in Non-thermal Plasma | 10.1007/s13369-022-07043-6 |
2023-01-01 | In this work we present a control architecture to reduce the vibration of the tower of a wind turbine (WT) using the pitch angle. The parameters of the active tower damping (ATD) control are optimized by the simulated annealing algorithm, which imitates the physical process of steel hardening. To validate the approach, a linearized model of a 5 MW turbine is used at 13 m/s of wind speed. Results show how the optimized active tower damping is able to dampen the oscillations and thus, the peaks and the amplitude of the vibrations are much smaller. This allows to increase the efficiency and reduce the fatigue of the WT. | Pitch-Based Wind Turbine Tower Vibration Damping Optimized by Simulated Annealing | 10.1007/978-3-031-18050-7_51 |
2023-01-01 | Although seismic isolation techniques have been widely recognized as effective in modifying the seismic response of protected structures, clearance parts to accommodate the large relative displacement anticipated in seismic design are likely to encounter pounding problems. In most cases, the pounding is unpredictable and unmeasurable and can compromise the accuracy of system identification approaches. To decide whether an isolation structure could continue to be used after strong earthquakes, parameter estimation based on earthquake monitoring systems should identify the variation of structural parameters related to damage, under uncertain pounding problems. The Kalman filter is a versatile system identification method for dealing with modeling and measurement uncertainties. The present study investigates the effectiveness of the unscented Kalman filter under such situations for the measured data from the shaking table (E-defense) test of an isolation building. Specifically, the base layer of the building was designed to collide with the retaining walls to evaluate the influence of pounding. The results show that the parameters related to the isolation layer can be estimated with acceptable accuracy when the proper conditions are met. | Parameter Estimation for Seismic Isolation Structures in the Presence of Pounding Problems by Unscented Kalman Filter | 10.1007/978-3-031-39117-0_61 |
2023-01-01 | Traditional machine tools with cast iron or cast steel structures experience structural vibrations, resulting in the poor surface finish on manufactured components. The static and dynamic characteristics of machine tools are improved by steel-reinforced epoxy granite. Topology optimization is a mathematical approach for optimizing the design space for a given set of objectives, loads, boundary conditions and constraints to maximize system performance. The present work focuses on optimizing the steel reinforcement configuration of a vertical machining centre column made of epoxy granite (EG). Topology optimization is carried out with the objective of maximizing the stiffness and natural frequencies of the steel-reinforced epoxy granite column while minimizing the mass of the structure. Multiple design configurations for steel reinforcement are evolved based on topology optimization, and numerical investigations are carried out by FEA. The static and dynamic characteristics of the EG columns with optimized steel reinforcements are compared with the existing CI and SREG columns. The results reveal an 8–20% improvement in natural frequencies and a 12% decrease in the mass of steel reinforcement than that of the existing SREG column. | Multi-objective Topology Optimization of Steel Reinforcement for Epoxy Granite VMC Column | 10.1007/978-981-19-4556-4_28 |
2023-01-01 | Composites are extensively used in various fields such as civil, aerospace, naval due to their high specific stiffness and strength. These properties are adversely affected due to damage. For damage detection, vibration-based methods are generally used which use modal parameters, i.e. modal frequencies, mode shapes and modal damping ratios. These modal parameters depend on the physical properties of the system, i.e. mass, stiffness and damping. Among these properties, damping is the most sensitive to damage. Therefore, the occurrence of damage should be sensed through changes in damping. Further, in order to localize the damage, a support model for damping is needed to spatially isolate the origin of the changes. Unfortunately, damping depends on numerous known and unknown physical phenomena that makes it difficult to model or estimate. In this study, first variation of modal damping ratios with damage in a composite column has been shown. Then, a new model of damping, called mode specific damping, is proposed. The performance has been checked through numerical simulations and compared with the Rayleigh model of damping. | Mode Specific Damping Estimation—An Inverse Damping Modelling Technique | 10.1007/978-981-19-9394-7_22 |
2023-01-01 | Background Metal lattice structures obtained through Selective Laser Melting may increase the strength-to-weight ratio of advanced 3D printed parts, as well as their damping properties. Recent experimental results showed that AlSi10Mg and AISI 316L lattices are characterized by higher Rayleigh damping coefficients with respect to the fully dense material. However, some unclear or contradictory results were found, depending on the experimental setup adopted for modal analysis. Objective In this work the influence of the experimental setup when performing modal analysis on different SLM AISI 316L lattice structures was deeply investigated. The study provides a critical comparison of various experimental modal analysis approaches, allowing to evaluate the influence of external damping sources and material internal damping phenomena. Methods The dynamic behaviour of SLM AISI 316L specimens incorporating lattice structures was estimated by means of pulse testing and sinusoidal excitation through an electromagnetic shaker. The validity of the viscous damping model was assessed by means of sinusoidal excitation with different levels of vibration velocity. Moreover, the influence of experimental setup on modal analysis results was critically evaluated, by considering different actuators, contact and non-contact sensors and boundary/clamping conditions. Results The classical viscous damping model describes with good approximation the damping properties of SLM lattice structures. When exciting single specimens in free-free conditions, those embedding lattice structure and unmelted metal powder filler were characterized by superior internal damping properties with respect to the specimens incorporating the lattice structure without any filler, which was however more effective than the full density equivalent material. Most of the other experimental setups introduced additional external damping sources, that could alter this important outcome. Conclusions SLM lattice structures embedded into 3D printed components provide superior damping properties against mechanical and acoustic vibrations and the metal powder filler does significantly enhance such damping capacity. A correct estimation of material internal damping was achieved by applying non-contact sensors and free-free boundary conditions, whereas other experimental setups were partly inadequate. | Influence of the Experimental Setup on the Damping Properties of SLM Lattice Structures | 10.1007/s11340-022-00898-8 |
2023-01-01 | Deformation history integral type hysteresis (DHI) model is a numerical model for seismic isolation bearing which has high non-linearity in restoring force characteristics, such as high-damping rubber bearing (HDR). While the model can represent the complex behavior of HDR including performance change by temperature, aging and manufacturing variation, the scragging effect, which is generally considered in practical design of seismic isolation system, is not taken into account in the conventional model. In this study, the model was improved by defining scragging effect as a function of performance change ratio. In order to confirm the accuracy of the proposed model, time history analysis was carried out and the results of analysis were compared with those of substructure real-time online testing (SROLT) using scaled model of HDR. The analysis results showed good agreement with those of SROLT and the applicability of improved DHI model was verified. | Development of an Improved Deformation History Integral Type Hysteresis Model for High-Damping Rubber Bearings | 10.1007/978-3-031-21187-4_14 |
2023-01-01 | In this talk, a piezoelectric shunt damping is introduced to an acoustic black hole beam to form an acoustic black hole (ABH) piezoelectric composite structure, and its vibration characteristics are analyzed by a semi-analytical method. Based on the Hamilton principle, the Mexican hat wavelet is used as the shape function, and the energy method is used to solve the free and forced vibration of the acoustic black hole beam structure with PZT. The present results agree with those of the finite element method. To improve the effectiveness of the acoustic black hole, an external shunt circuit is connected to the PZT and shunt damping with the local resonance mechanism is introduced. The vibration characteristics of the beam with shunt damping and ordinary damping are compared and analyzed. The vibration suppression of ABH beam by piezoelectric shunt damping with different positions is discussed, and the optimal position is obtained. The designed acoustic black hole beam with shunt damping is significantly attenuated than the traditional damping layer acoustic black hole beam, which provides a new idea for the low-frequency vibration control of the acoustic black hole structure. | Vibration Suppression of Acoustic Black Hole Beam by Piezoelectric Shunt Damping with Different Positions | 10.1007/978-3-031-15758-5_101 |
2023-01-01 | The article considers the need to implement dynamic modes - acceleration and deceleration by lifting mechanisms, with given restrictions on speed, acceleration, and its derivative. The optimal diagram was presented according to the criterion of the maximum speed for the lifting mechanism. Also, the optimal movement diagram was presented under restrictions on the loss number of the lifting mechanism components. A generalized structural diagram has been synthesized, which makes it possible to analyze nonlinear oscillatory lift systems, as objects of regulation, with arbitrary parameters of the lifting mechanisms and arbitrary laws of their control. Recommendations are proposed for improving the quality of the dynamic modes of lifting mechanisms due to vibration damping. The solution of minimizing the vertical vibrations of the elements of lifting mechanisms arising in dynamic modes by forming the required mechanical characteristics of the engine with specific rigidity parameters is considered. Dependencies of the damping coefficient of the equivalent vibrational link on the rigidity of the mechanical characteristics, the recommended values of the rigidity of the mechanical characteristics on the values of the mass ratio, and the maximum value of the damping coefficient on the mass ratio are given. It is shown that the choice of the required rigidity of the mechanical characteristics of the electric motor of the lifting mechanism increases the damping coefficient and reduces the oscillation in transient modes. | Vibration Damping of Lifting Mechanisms | 10.1007/978-3-031-16651-8_38 |
2023-01-01 | This paper attempts to predict the response of a rotor-bearing system with external damping by training a neural network model using the frequency domain historical data obtained from multiple simulations. In general prediction of response for a rotor dynamic system is performed by detailed finite element modeling and/or testing on the test bench. This involves the modeling of rotors, bearings, and housings. Accurate finite element modeling involves considering various important aspects such as material damping, structural damping, and bearing non-linearities. Design is an iterative process and any change in the design of bearings or housings or dampers necessitates the repetition of the FE modeling and analysis. In this work, a method to overcome this repetitive process is presented. A neural network model is built by mapping the geometric features of bearing housings and dampers, unbalance amplitude and phase, oil viscosity, and rotational speed with the frequency domain response at the front and rear bearing locations. The model is trained using a set of input features and target variables by tuning the hyperparameters of the model. The performance of the model is then tested on unseen data. The predicted results closely match the true vibration responses. This neural network regression model can be extended to real data from the rotor dynamic test rig as well. | Vibration Response Prediction in Rotor Systems with External Damping by Deep Learning Using Geometrical Features | 10.1007/978-981-99-4721-8_17 |
2023-01-01 | The 1915 Çanakkale Bridge is a recently completed suspension bridge, characterized by a main span of 2023 m which is the world’s record. The bridge restraint system is quite complex in order to guarantee safety under traffic, wind and seismic actions. It comprises 8 fluid viscous dampers, 4 large bearings designed to withstand compression load as well as tension load and horizontal displacement, 8 lateral elastomeric bearings for transversal restraint and 8 hydraulic end-stop devices. This paper focuses on the eight special fluid viscous dampers that give large energy dissipation capacity to the bridge under earthquake. They are characterized by a load capacity of 5000 kN, a stroke of ± 1.25 m and a maximum design velocity of 1 m/s. The paper describes the dynamic and static tests carried out on two full scale viscous dampers according to the test protocol that includes the European Standard EN 15129:2009 type tests and additional contract specifications. | Fluid Viscous Dampers for the 1915 Çanakkale Bridge in Turkey | 10.1007/978-3-031-21187-4_40 |
2023-01-01 | Semi-active suspension systems utilizing magneto-rheological damper have been used especially in the vehicle due to their simple design and control with the effective outcome. Nevertheless, the FL controller design without considering the intelligent algorithm utilizing the FL gain scaling leads to the undesirable condition of the vehicle body. Thus, this study is conducted to develop and evaluate the performance of the particle swarm optimization discoverer (PSOD) in tuning the fuzzy logic (FL) controller in a semi-active suspension system while being compared to the original particle swarm optimization (PSO) and passive system. Taking an acceleration of the suspension system response as an objective function, the PSOD strategy is an attempt to find and search for an optimum value of the gains that able to be a sort of contact information for improving the targeted value obtained from the FL controller. The application of this system is simulated in MATLAB Simulink. The effectiveness of the PSOD was shown by the simulation result with as high as 63.79% and 59.82% of improvement in terms of sprung displacement and sprung acceleration, respectively. This result indicates that the PSOD could provide improvement for vehicle ride comfort and effective improvement solution over the PSO. | Fuzzy Logic Controller by Particle Swarm Optimization Discoverer for Semi-Active Suspension System | 10.1007/978-981-19-8703-8_17 |
2023-01-01 | Some mathematical tools, needed to perform stability and bifurcation analysis, are introduced. After a brief introduction to general dynamical systems, the discussion is focused on mechanical systems. The nonlinear equations of motion of a general system are introduced and then expanded in series. Structural and geometric matrices, related to internal and external forces, respectively, are identified. The linear stability analysis of an equilibrium point, based on detection of the eigenvalues of the linearized equation of motion, is conducted. Discussion is then focused on conservative and circulatory systems and on the effects of damping on their stability. The general concepts are exemplified with reference to the planar mathematical pendulum, for which both the dynamic criterion and the energy criterion of stability are used. Moving on to consider parameter-dependent systems, the notions of equilibrium path , and trivial or non-trivial fundamental paths , are introduced; moreover, the techniques for determining bifurcation points occurring along them, are illustrated. The mechanisms leading to bifurcations of conservative and circulatory systems, without or with damping, are discussed. | Stability and Bifurcation Linear Analysis | 10.1007/978-3-031-27572-2_3 |
2023-01-01 | The presence of moisture in historic masonry walls represents one of the main sources of decay for cultural heritage and materials, besides causing unhealthy indoor conditions and worsening the thermal performance of the building envelope. In fact, moisture causes and/or exacerbates different deterioration mechanisms, such as salt crystallization, freeze-thaw cycles, biological growth, etc. Given the importance of moisture in materials, there are many techniques aimed at determining moisture content in structures, but the most common ones only provide qualitative results or do not allow reliable repeated measurements over time, which is a severe limitation when continuous monitoring is necessary. In this perspective, the MIMESIS project (funded by Emilia-Romagna Region, Italy) aims at developing a range of sensorized materials for the remote monitoring of moisture, temperature, pH and detachment, useful to determine the ‘health state’ of historic buildings. It is also expected that the sensorized materials give a warning when critical situations are reached, allowing to carry out adequate interventions before irreversible damage occurs. In this paper, a brick-based sensor suitable for measuring moisture content in masonry was developed and tested. The sensing element was originally designed for agriculture, to measure the ‘soil water tension’, hence an investigation about the applicability to building materials and a calibration in bricks was necessary. The results are encouraging and suggest that this new sensorized brick could be applied for the continuous monitoring of moisture in historic masonry. | New Sensors for Moisture Monitoring in Historic Walls: Preliminary Results | 10.1007/978-3-031-21735-7_87 |
2023-01-01 | To alleviate the detrimental diagonal bracing effect of the traditional rigid-connected reinforced concrete (RC) flight to the boundary frame under lateral inputs, the study proposes an innovative low-damage stair system: prefabricated RC stair isolated by high damping rubber (HDR) bearings. The remarkable properties of the HDR bearings are firstly verified by material tests. To understand the behavior of the novel system, a quasi-static test is conducted on two full-scale stair systems, and a parametric study of the design parameters of the HDR bearings is carried out. Test results confirm that the proposed system could mitigate the detrimental diagonal bracing effect of traditional RC flight by the HDR bearings. Consequently, no crack can be observed in the RC flight at the inter-story drift ratio (ISDR) of 2.0%, and only three horizontal cracks are detected at the bottom of the RC flight under the ISDR of 4.0%. Moreover, benefitting from the sliding mechanism of the developed stair system, the novel stair system is characterized by stable hysteretic responses and energy dissipation capacity at each loading stage and has about twice the equivalent viscous damping ratio to the traditional stair system. The parametric study shows that the rubber thickness of the HDR bearings has a remarkable effect on improving the seismic performance of the developed stair system, while the shear modulus and rubber hardness of the HDR bearings have a slight contribution to enhancing the lateral bearing capacity of the system. | Seismic behavior of prefabricated reinforced concrete stair isolated by high damping rubber bearings | 10.1007/s10518-022-01548-z |
2023-01-01 | This chapter presents the most basic oscillator model, the simple harmonic oscillator. We introduce the concept of the phase plane and extend our discussion to the damped and driven simple harmonic oscillator models. We consider the relationship of the quality factor to the rate of change of the oscillator energy and the oscillator lineshape. We finally present linear oscillator models and highlight their usefulness and limitations. | Basics of LC Oscillators | 10.1007/978-3-031-31086-7_1 |
2023-01-01 | There will be vibrations caused by friction between the rotating workpiece and the insert on the boring bar during the boring process. Vibrations that occur in the workpiece can be suppressed with a Dynamic Vibration Absorber (DVA). Therefore, the boring process produces a rough surface and damages the components of the lathe. In this research, DVA is placed on a workpiece by utilizing force damping in the radial direction and it is called as Rubber Radial Vibration Damper (RRVD) with rubber as a damping element. An analysis of the effect of RRVD addition on the vibration reduction response of the workpiece was carried out. The variations in this study are mass of RRVD (AISI 4340 and Copper Alloy), cutting parameters, and the ratio of length per diameter (L/D) of the workpiece overhang 7, 8, and 9. The simulation results showed that the main system's highest natural frequency and amplitude occurred at the L/D 7 without RRVD or with RRVD. In addition, the RRVD Copper Alloy mass variation has a lower natural frequency and amplitude than the AISI 4340. Based on this research, it was found that the most stable and well-reduced system was in the main system with L/D 8 and using RRVD Copper Alloy mass. | Analysis of Vibration Characteristics Due to the Effect of Adding Rubber Radial Vibration Damper (RRVD) to the Boring Process | 10.1007/978-981-19-0867-5_9 |
2023-01-01 | Floating bridges are efficient and rapid solutions in crossing water gaps when the conditions are not suitable or economic for the construction of other conventional bridge systems. Using floating bridges is promoted to be a good solution in various applications such as rapid disaster relief, military gap crossing operations, and connecting lifelines of cross-shore territories. However, design and analysis of floating bridges are challenging engineering tasks where various factors have to be considered such as water structure interaction, wind, and different traffic loading cases. Moreover, inherit structural damping is another concern to simulate the structural energy dissipation and capture to a considerable limit the bridge dynamic behavior. In this study, the Rayleigh damping method is used to calibrate the dynamic structural behavior of a ribbon floating bridge system. The floating bridge is composed of the assembly of three different floating bridge structures: The Heavy Communication Bridge (HCB), the assault floating bridge (PMM71), and both are connected using a pontoon unit named New Connection Pontoon (NCP). The NCP is fully manufactured of steel sheets and sections and developed to integrate a traffic line through connecting the HCB and PMM71. The whole bridge assembly is subjected to tracked tank load of Military Loading Class of 70 tons (MLC70). Due to the request for rapid and reduced assembly time, a Hybrid NCP (HNCP) is redesigned of FRP composite laminated sheets and a steel skeleton to minimize weight. A 3D numerical model is developed of the full floating bridge system solution PMM71, HNCP, and HCB using ANSYS FE Package. The dynamic structural response is captured at two tracked passing vehicle speeds, 8 km/h and 16 km/h. A modal analysis is performed to quantify the cumulative bridge mass participation, mass, and stiffness Rayleigh factors based on the cyclic frequency values. The baseline steel NCP dynamic structural draft values are calibrated using the Rayleigh method and validated with experimental results. Furthermore, the structural response of the full-bridge system involving the HNCP is investigated. The obtained results showed the difference in draft values between the steel NCP and the experimental values are minimized to reach 3.88% and 4.8% for 8 km/h and 16 km/h vehicle speeds, respectively. A comparison between draft values obtained for the baseline steel NCP and HNCP is performed. The results showed an improvement of the draft values by 3.8% and 3.69% for 8 km/h and 16 km/h vehicle speeds, respectively. The numerical model is concluded as a promising model for studying the structural behavior of a fully composite laminated floating bridge system. | Dynamic Response Calibration of Hybrid Floating Bridge System Using Rayleigh Damping | 10.1007/978-3-031-09409-5_3 |
2023-01-01 | In this paper, a novel truss-inertial mass damper (IMD) system is developed for seismic response mitigation of atrium buildings with an internal structure. An IMD with nonlinear damping characteristic is introduced to provide passive vibration control, and the unsynchronized dynamic response between the tops of the building and the structure inside the atrium is utilized to activate the IMD for energy dissipation purpose. Parametric studies are conducted to evaluate the effectiveness of the truss-IMD system on suppressing structural responses under earthquakes, with two performance indices set to reflect the response intensities in interstory drift and story absolute acceleration. Results indicate that for a preset IMD nonlinearity, there exists an optimal combination of inertance and damping coefficient to maximize a building performance for a given equivalent stiffness of the truss and internal structure. Results also show that the maximum achievable structural performance and the corresponding optimal IMD design parameters generally increase with increasing effective stiffness for a given velocity exponent. Multi-objective optimizations are also performed to further evaluate the capacity of the proposed system in reducing the interstory drift and story acceleration simultaneously using a 6-story building. | Seismic Response Mitigation of Atrium Buildings with Truss-IMD System | 10.1007/978-981-19-7331-4_14 |
2023-01-01 | This chapter, the third chapter of the “Infection” part, presents some aspects of host immune defense against pathogens by focusing on damage-associated molecular patterns (DAMPs), which—in concert with microbe-associated molecular patterns (MAMPs)—drive innate and adaptive immune responses in infections. Both categories of molecules are sensed by various families of pattern recognition molecules (PRMs) which are briefly reviewed by highlighting some downstream signaling protein complexes such as supramolecular organizing centers, the myddosome, the triffosome, and inflammasomes. Through these signaling complexes, DAMPs/MAMPs activate the innate immune system essential for host defense. Following is a discussion of some aspects of the regulatory processes of defense responses to pathogens mediated by DAMP/MAMPs, which are tightly regulated at multiple cellular and molecular levels to prevent potentially life-threatening pathological processes. Such processes include control of appropriate DAMP-triggered promotion of infectious inflammation and timely regulated suppressing DAMP (SAMP)-driven resolution of inflammation. Another important topic discussed in this chapter refers to the concept of an interplay between MAMPs and DAMPs that initiates and shapes the protective, antigen-specific adaptive immune responses to pathogens. Besides outlining some basics of the distinct T-cell- and antibody-mediated response, it is emphasized that DAMPs are the key players in providing upregulation of costimulatory molecules on antigen-presenting cells such as dendritic cells (DCs), which are absolutely required for their metamorphosis into immunostimulatory DCs needed for full activation of T cells. Finally, some problematic issues related to the role of DAMPs in infections are discussed, such as (1) their interplay with MAMPs in mounting robust inflammatory/immune defense responses by pointing to the changing role of MAMPs, and (2) their still-elusive timely (simultaneous or sequential) recognition in concerted action with MAMPs. | The DAMP-Driven Host Immune Defense Program Against Pathogens | 10.1007/978-3-031-21776-0_4 |
2023-01-01 | In the maintenance of cable structures, such as cable-stayed bridges and extra-dosed bridges, it is necessary to estimate the tension acting on the cables. The safety of a cable is assessed by comparing the tension acting on the cable and the allowable value. In current Japanese practice, the tension of a cable is estimated using the vibration method or the higher-order vibration method, which considers the natural frequencies of the cable. However, in recent years, the aerodynamic vibration of cables caused by wind has become a problem owing to the recent increase in the cable length and low damping performance of the cable itself. In such a case, dampers are installed onto the cables to suppress the aerodynamic vibration of cables. Because the damper changes the cable’s natural frequencies, the vibration and higher-order vibration methods are inappropriate for estimating the tension of a cable with a damper. With this background, the authors developed a tension estimation method for a cable with a damper where a cable is modeled with a tensioned Bernoulli–Euler beam. The theoretical equation is derived, which relates the natural frequencies with the tension and bending stiffness of the cable and damper parameters. The method inversely estimates the tension and bending stiffness of the cable and damper parameters simultaneously from the natural frequencies. In this paper, the authors’ tension estimation method is first introduced. Then the validity of the method is shown through numerical simulations. Then the method is verified through a laboratory experiment. Moreover, the field measurements of a cable-stayed bridge in Japan were conducted to verify the method. It was found that the method could estimate the tension of a cable with the damper with high accuracy. In this way, the validity of the method was confirmed. | Tension Estimation Method for Cable with Damper and Its Application to Real Cable-Stayed Bridge | 10.1007/978-3-030-93236-7_32 |
2023-01-01 | Limewashes have been used as finishing coats for walls since ancient times. Its protective, aesthetic, antiseptic properties and cost-efficiency are the ground for its worldwide application. The main drawback of lime-based paints is their low durability towards the action of water, particularly wind-driven rain. Additives that grant water-repellent properties have been added to these paints to overcome this issue. Among these additives, vegetable oils have been reported worldwide in ancient documents. In this work, three vegetable oils have been selected based on their composition and promising results in previous studies, global availability, and cost-efficiency: rapeseed, sunflower, and sunflower oil with high oleic acid content. Additionally, a commercial water-repellent lime putty with the addition of olive oil was included to prepare a limewash and compare it with the lab-prepared paints. Two types of stone with very different porous structures were used as substrates to compare the effect of the paints on their water transport properties. The substrate with higher porosity and wider pores showed promising results in terms of water-repellence and drying. In contrast, the stone with lower porosity and fine pores did not show good results. Based on this study, suggestions for further research to improve the performance of the paints in substrates with low porosity and narrow pore size distribution are given. | Limewashes with Vegetable Oils: Water Transport Characterisation | 10.1007/978-3-031-31472-8_12 |
2023-01-01 | Current design practices for base-isolated structures generally conduct in plane time-history analysis using a single horizontal seismic component of the ground motion. However, base-isolated structures are subjected to bi-directional horizontal ground motion. So, some error included in the evaluation of the maximum displacement of the seismic isolation layer and damage to the dampers during an earthquake. This research focuses on the damage on U-shaped steel dampers, widely used in Japan as seismic isolation devices. A quantitative comparison between the damage on damper obtained using: (1) a one-directional (1D) model (SDOF system with single seismic component), and (2) a bidirectional (2D) model (Multiple Shear Springs with 2DOFs and both seismic components) is conducted. From analytical results, damage on damper up to fracture were compared. Then, the safety factor that should be considered in the current design based on 1D analysis was examined. Moreover, the values of the maximum displacement of the isolation layer were also compared and the safety factor that should be considered in the current design method was also examined. | Effect of Bi-directional Ground Motion on the Response of Base-Isolated Structures with U-Shaped Steel Damper | 10.1007/978-3-031-36562-1_16 |
2023-01-01 | In this work, linear and nonlinear vibration analyzes of a drum type washing machine having two springs and two dampers have been performed numerically. The effects of parameters such as linear spring stiffness, nonlinear spring stiffness, and damping coefficient have been investigated. A mathematical model of horizontal axis type washing machine by considering the whole system as a single degree of freedom system is formed. Since vibration level is large during spinning cycle, hence nonlinear stiffness of spring is considered, and a comparison of the linear and nonlinear mathematical model is carried out. The numerical solution of this mathematical model is found by using Runge Kutta 4th order method using MATLAB. From this study, it has been found that the damper with a high-damping coefficient and linear spring with low stiffness effectively reduce the vibration level. Also, steady-state vibration level remains almost unaffected by varying the stiffness of spring with cubic nonlinearity. | Numerical Study of a Horizontal Axis Washing Machine for Linear and Nonlinear Vibration | 10.1007/978-981-19-2188-9_70 |
2023-01-01 | This paper presents a new Stiffness Relaxation method of the classic Bouc-Wen hysteresis model, used to simulate the hysteresis loop of Romanian friction dampers SERB-C-194 in seismic analysis of buildings equipped with this type of seismic dampers. The classic model does not accurately simulate the hysteresis loop of friction dampers because it keeps constant the stiffness of the damper as its stroke increases. Friction dampers are devices that strengthen the stiffness as the damper stroke increases. The proposed new method aims to simulate a stiffer damper but which is affected by the phenomenon of Stiffness Relaxation. Such methods have been proposed by Sivaselvan and Rheinhorn [ 1 , 2 ] which have introduced a Stiffness Relaxation factor R _ k which only works for the situations of continuous increase of the damper stroke. Our method offers a way to solve this problem by an “envelope” of the damper displacements. In this case the hysteresis loops of the new model are in accordance with the real situation observable in the hysteresis loops obtained experimentally. The new differential hysteresis model was implemented in the HistPlot program developed by the authors and is useful in determining the parameters of the differential model for simulating experimental hysteresis loops. This improved model is further used for earthquake dynamic simulation of buildings equipped with anti-seismic dampers using the GenEcAm program developed by the authors. | Software Application for Stiffness Relaxation New Method of Bouc-Wen Hysteresis Differential Model Used in Simulation of Romanian Friction Dampers | 10.2991/978-94-6463-152-4_61 |
2023-01-01 | In this paper, we estimated the hydrodynamic force in an array of cantilever beams separated by a distance $$\bar{s}$$ s ¯ oscillating in a viscous fluid. The beam is assumed to be sufficiently long to consider 2D flow and has symmetric as well as asymmetric shape morphing curvature while oscillating in a fluid. The fluid-structure interaction problem is modelled by considering the unsteady Stokes equation. The resulting 1D boundary integral problem is solved by the boundary element method (BEM) numerically in MATLAB to obtain the desired pressure distribution on the beam. It is found that as the frequency oscillation of the rigid beam is increased, both the damping as well as added mass effects are decreased at different rates due to the gradual decrease in unsteady viscous layer. Finally, the hydrodynamic coupling effect on the beam is demonstrated at $$\beta =0.1$$ β = 0.1 . However, for increase in the symmetric and asymmetric shape morphing parameters, the hydrodynamic decoupling appears lower than the gap ratio 5. The cantilever beam with optimal shape morphing parameter can be useful for the optimal designs of atomic force microscopy (AFM). | Two-Dimensional Hydrodynamic Forces in an Array of Shape-Morphed Cantilever Beams | 10.1007/978-3-031-20353-4_18 |
2023-01-01 | The new cable-stayed arch bridge Tegenbosch (Eindhoven, the Netherlands) needed an assessment of its dynamic behaviour under wind loading due to its slender design. Because of wind-induced vibration issues on a number of bridges in the Netherlands with similar designs, it was decided to examine if vortex excitation, wind-rain induced vibration, galloping or parametric excitation might occur. Measurements were performed to determine the natural frequencies and damping ratios of the 32 cables and the deck. All cables were individually assessed, by measuring the vibrations of the cables induced with a step relaxation excitation by pre-tensioning and releasing a lashing strap. The natural frequencies of the cables were determined by evaluating the transfer functions of the measured excitation force and acceleration; damping ratios were obtained with the half-power bandwidth method. To determine the natural frequencies of the deck, 12 accelerometers were placed at different locations on the deck, after which the deck was excited using a 250 kg impact hammer at five locations. The first natural frequency of the cables varied between 2.11 Hz for the longest cable and 8.51 Hz for the shortest cable. The lowest value of the logarithmic decrement for damping found was 0.0059. Based on the damping values, a lowest Scruton number of 58 was determined using NEN-EN 1991-1-4, meaning that vortex excitation will not lead to any problems. Using the measured natural frequencies it is shown that the critical wind velocity for galloping is larger than the occurring wind speed. The same conclusion holds for wind-rain induced vibrations, where the critical velocity is calculated using the natural frequency and the damping value. The lowest horizontal natural frequency of the deck was found to be 0.41 Hz; the lowest vertical natural frequency is 2.05 Hz. Since the natural frequencies of some of the cables coincide with the natural frequencies of the deck, parametric excitation might occur. In case parametric excitation is indeed a problem in practice, it is advised to add extra damping to the system. | Vibration Measurements on a Cable-Stayed Cyclist Arch Bridge for Assessment of the Dynamic Behaviour | 10.1007/978-3-030-93236-7_12 |
2023-01-01 | Even though there are so many studies upon optimization of supplemental damping devices integrated to structural systems, the vast majority of them remain only as a subject of the research articles of the Journals and cannot find a place itself in common practice due to lack of the regulations about the issue in codes and standards. In this paper, the issue is dealt with the most fundamental inputs and outputs of a general problem. All efforts are made to show how the procedure could frequently be used in common practice and what the attained benefits could be from the design and application point of view. The analysis of the structural systems in which the “seismic response control systems” have been adapted requires considering the special numerical analysis techniques which provide “solutions in frequency domain”. By this means, not only the “dynamic response characteristics” of the structure shall be determined but also the variation of this response with the change of the “design parameters forming the structural control systems” shall be able to be investigated from the optimization point of view. Since conventional analysis tools and methods are not capable of providing such information, advanced numerical analysis method based on the “state-space approach” is considered along with the “gradient based optimization algorithm” in the proposed study. In this paper, viscous fluid dampers are examined as a supplemental damping devices in the analysis of a multi degree of freedom structure. Dampers are modelled with the Maxwell model in which the spring and the dashpot are placed in series. For a given brace stiffness, viscous damping coefficients and the distribution of the damping devices between stories are optimized by a procedure to reach a “target performance level”. The optimization is achieved by minimizing an “objective function” which rates the structural responses of the controlled system with the uncontrolled one. Generally, mean square responses of the inter-story drift, floor acceleration and base shear are among the structural response quantities considered for this procedure. | Application of the Gradient Based Optimization to the Structural Systems with the Supplemental Damping Devices | 10.1007/978-3-031-21187-4_41 |
2023-01-01 | Piezoceramic (PZT) layers are more widely used as vibration energy harvesters. These materials have found a greater application both in actuation and sensing. In this study, the characterization of energy output from optimally located PZT under base excitation and force excitation is investigated and experimentally correlated. SDOF (Single Degree of Freedom) mathematical modeling is commonly used to estimate the voltage generated across the PZT which may result in inaccurate output. The cantilever beam with PZT is modeled as a continuous system with discrete PZT patches at high strain zones depending on the mode under consideration. The output voltage from PZT can be enhanced significantly using tip mass. This has better applications in MEMS devices. A detailed simulation study and experimental verification have been investigated on a cantilever beam with tip mass. The space constraints in MEMS devices call for using a tip mass to generate higher voltage for a smaller beam length. The influence of rotary inertia of tip mass is primarily focused. The sensitivity parameters consider the beam to PZT length ratio, Young’s modulus ratio and tip mass. Optimization criteria to achieve maximum energy generation has been studied using the mode superposition method to find the optimal voltage generated across the PZT. Electrodynamic shaker, B&K accelerometer, conditioning amplifiers and National Instrument data acquisition are used during the experimental investigation. The energy thus harvested from a beam with tip mass and PZT can encourage the use of power generated for power supply to the MEMS device. The results are encouraging to implement in MEMS devices. | Enhanced Energy Harvesting Application of Piezoceramics (PZT) in MEMS Devices | 10.1007/978-981-99-4721-8_4 |
2023-01-01 | Accurate prediction of roll damping moments of ships is important to predict roll responses accurately. A method for estimating the roll damping moment in the time domain is necessary for estimating parametric rolling and other phenomena in irregular waves. In this paper, we investigate the characteristics of the roll damping moments acting on bilge-keels by utilizing CFD computation to propose a time-domain prediction method for the bilge-keel component. The roll damping moment acting on the bilge keel depends on the current and previous rolling of the hull. The reason for this is that the vortices generated at the bilge keel are rapidly strengthened by the vortices generated by the previous rolling. A method for predicting the roll damping moment of the bilge keel is proposed considering this effect. | Study on Bilge Keel Component of Roll Damping for Non-periodic Motion | 10.1007/978-3-031-16329-6_28 |
2023-01-01 | In this chapter, the temperature-dependent vibration damping in C/SiC composites with different fiber preforms under different vibration frequencies was investigated. A micromechanical temperature-dependent vibration damping model was developed to establish the relationship between composite damping, material properties, internal damage mechanisms, and temperature. Effects of fiber volume, matrix crack spacing, and interface properties on temperature-dependent vibration damping of CMCs and interface damage were analyzed. Experimental temperature-dependent composite damping of 2D and 3D C/SiC composites was predicted for different loading frequencies. | Temperature-Dependent Vibration Damping of Ceramic-Matrix Composites | 10.1007/978-981-19-7838-8_4 |
2023-01-01 | The uniaxial Bouc-Wen hysteresis model is well established for simulating the bearing behavior in unidirectional excitations. However, the real scenario is quite different as seismic control devices like high damping rubber bearing exhibit the influence of the orthogonal excitations. In the current work, the feasibility of modeling the high damping rubber bearing (HDRB) using biaxial Bouc-Wen model is established. Further, the comparison of uniaxial Bouc-Wen and biaxial Bouc-Wen model is made for HDRB through responses and the correlation coefficients. The effect of bidirectional coupling compared with the uniaxial model is investigated for ten real earthquake input excitations. Further, the results validate the suitability of the biaxial Bouc-Wen model for simulating the interaction effects among HDRB. The changes in the correlation coefficients are significant when interaction is considered. Moreover, it was found that there is under estimation of peak displacement if interaction effects are ignored. | Influence of Biaxial Interaction in Bouc-Wen Hysteresis Model Used for Modeling High Damping Rubber Bearing Under Bidirectional Excitation | 10.1007/978-981-99-1608-5_11 |
2023-01-01 | In this paper, we consider a modified Gough-Stewart platform (MGSP) where two groups of three legs meet at two concentric circles on both top and bottom platforms. The geometry of the MGSP is chosen such that all the first six natural frequencies are equal for a typical payload mounted on the top platform. Additionally, in the top platform, made up of an aluminum honeycomb sandwich, the empty cells of the honeycomb core are filled with damping particles (DPs) to introduce passive damping in the system and to limit the resonance responses. A finite element model (FEM) of the MGSP is developed to quantify the performance in terms of frequency response functions (FRF), resonance peaks, and the damping introduced by the damping particles. The FEM model of the MGSP is combined with the discrete element model (DEM) of the damping particles to compute the effect of the particles on the overall dynamics and damping behavior of the platform. The effect of DPs on the transfer function is evaluated by solving the equations of motion of the DPs and the FEM model of the MGSP simultaneously. Finally, the FRF between the bottom platform and the mass center of the payload is computed for assessing the effectiveness of DPs, the transfer functions between the base excitation and mass center of the payload with respect to four inputs—sine swept inputs $$X$$ , $$Z$$ , $$\theta_{x}$$ , and $$\theta_{Z}$$ applied separately at the base of the platform—were computed for 25%, 50%, 75%, and 93% fill fractions. The peaks at resonances progressively decrease as the fill fraction was increased. For all the modes, it was seen that the damping introduced by damping particles results in the splitting of the modes and the formation of anti-resonance at resonance peaks. The damping introduced by the particles is more effective in longitudinal direction $$\left\| {Z/Z} \right\|$$ where there is a reduction from 25 to 8 with increasing fill fractions from 25 to 93%. The cross-axis transfer functions also seen to come down from 98 and 10 to 75 and 5 along the X -axis and Y -axis, respectively. | Vibration Isolation Characteristics of a Modified Gough-Stewart Platform with the Top Platform Filled with Damping Particles | 10.1007/978-981-19-3716-3_19 |
2023-01-01 | Damping modification factor of vertical response spectra (DMF_ V ) for 1%, 2%, 8% and 10% damping levels with that at 5% of the critical is explored for a period range of 0–4.0 s. The dependence of DMF_ V on seismological parameters (magnitude, epicentral distance and soil type) is studied and is shown to be weak and insignificant for practical purposes. Simplified relation for computing DMF_ V as a function of the period is proposed irrespective of any seismological parameters. | Simplified Damping Modification Factor for Vertical Response Spectra | 10.1007/978-981-99-1459-3_52 |
2023-01-01 | This chapter presents the state-of-the-art technology of shear thickening fluid (STF)-included vibration damping systems based on a literature survey. STF is a good candidate for vibration damping systems. Changeable rheology in STF provides excellent properties for designing anti-vibration structures. For this reason, researchers have made great efforts to adapt STF to various damping systems. In many anti-vibration applications, STF is embedded in the structural components for enabling them to gain damping properties. STF-integrated components play a role as self-damping devices by this way. Alternatively, STF is replaced by hydraulic oil in the conventional dampers to obtain adaptive damping characteristics in the machinery applications. STF, including anti-vibration pads, is effectively used in machinery as well. Another application area regarding the anti-vibration properties of STF is the machining operations. Currently, there is a very limited number of studies in this field. The main idea is supporting the workpieces with STF or integrating STF into the cutting tools to suppress the undesired vibrations originating from the workpiece/tool interactions. | Vibration Damping Systems with Shear Thickening Fluid | 10.1007/978-3-031-25717-9_5 |
2023-01-01 | In dealing with the shortage of traditional fossil energy, climate change and environmental pollution, wave energy has great potential. A wave energy converter is a device that converts wave energy into electrical energy. In this paper, the motion equation of a fully enclosed inertial mass wave energy converter is deduced, and a dynamic model of the fully enclosed inertial mass wave energy converter is established. Then, the average power of the wave energy converter at different frequencies is analyzed. Finally, the system mechanical parameters of the fully enclosed inertial mass wave energy converter are optimized based on the Moth-flame algorithm. | Response Analysis and Parameter Optimization of a Fully Enclosed Wave Energy Converter | 10.1007/978-981-19-9398-5_60 |
2023-01-01 | Damping is a desirable characteristic of a structure from a seismic point of view. Hence, in the dynamic investigation of the construction, damping modelling plays a vital part in gaining the harmless retort of the construction. Any deviation in the damping's representation from the actual damping in the analytical model could result in something between a minor failure and a catastrophic collapse, thus highlighting the magnitude of the shock in the dynamic analysis of structures. In contrast to the mass and stiffness matrix, the damping cannot be determined analytically, thus putting the dynamics analysis into a state of uncertainty. Various representations of damping have evolved over the years and are tailored to specific problems. It is generally accepted that there is no single, universally accepted method for analytically representing damping. In this article, an attempt was made by looking at the different shock absorber models currently in use in practice. | Analytical approach for damping model | 10.1007/s42107-022-00491-3 |
2023-01-01 | In this paper the small-signal stability of the New England 39-Bus Test System, which was modeled by PowerFactory of DIgSILENT, is studied for which a review of the state of the art of modal analysis as tool to obtain the oscillatory modes of an electrical power system. For its study and relying on a Python script, the engine mode of PowerFactory is used to determine the graphic evolution of the trajectory of the electromechanical oscillation modes, paying special attention to the critical modes whose frequency is found between 0.1 to 2 Hz. To obtain the critical modes for various scenarios, a script was developed in DIgSILENT Programming Language (DPL) by PowerFactory is proposed, which considering the variation of the generation offer, for this new operating condition, the modes of the system are determined by means of the modal analysis tool available in PowerFactory. Finally, and in order to visualize the effect produced by the displacement of the critical oscillation modes, through a short circuit in a transmission line is sought observe the RMS simulation of generator variables that vary its potency. | Leveraging Modal Analysis for Multi-scenario Power System | 10.1007/978-3-031-24327-1_18 |
2023-01-01 | A technique for using mathematical modelling for experimental obtaining of initial data is proposed, which consists in finding a previously created and verified mathematical model that describes a more technologically simple experiment and which includes the unknown characteristic of the material or product we need as a whole. Further, this more technologically simple physical experiment is carried out, and it is also carried out on the found mathematical model. By combining the results of physical and numerical experiments, we get the opportunity to determine a previously unknown characteristic of our material or product as a whole. This leads to a significant simplification and reduction in the cost of the process of obtaining initial data when creating adequate digital twins of complex technical products. The described technique is implemented on the example of the experimental determination of the damping coefficient of the tire of the track roller of the MT-LB tracked conveyor-tractor manufactured by the Kharkov Tractor Plant. | Using Mathematical Modelling for Experimental Obtaining of Initial Data when Creating Digital Twins of Complex Technical Products | 10.1007/978-3-031-31967-9_20 |
2023-01-01 | All types of waves both contain energy and transport that energy along with the wave propagation. Wave energy increases with larger amplitudes, so high amplitude waves correspond to louder sounds, larger ocean waves, and stronger earthquakes. This energy is often distributed unevenly over the different wavelengths or frequencies of the waves, which is shown graphically through intensity spectra. For example, plucking a guitar creates sound waves at distinct frequencies, namely the guitar string’s normal modes, which appears in a spectrum as a series of spikes. There are several ways to get this energy either into or out of waves. One is through abrupt energy transfer, such as by plucking the guitar string. Another is through resonance, in which energy is transferred between oscillating systems, such as from a parent who is pushing a child on a swing. | Wave Energy | 10.1007/978-3-031-24097-3_4 |
2023-01-01 | Building with timber is one of the ways to limit our carbon footprint, using a lighter material reduces the need for deep foundations and storing carbon in the structure itself is a solution for reducing the atmospheric part of it. Oppositely to the more classical materials of the building industry, steel and concrete, there is very limited knowledge about the behavior of tall slender timber structures under weather solicitations and the vibration of high-rise buildings made of wood is a main question limiting their development. The experimental European funded research program DynaTTB focused on the measurement, on site, on existing timber towers, of the structural damping with regard of the excitation by buffeting wind and the resulting comfort feeling of occupants. In France an experimental campaign on two tall composite towers, with a concrete core and timber walls and floors was achieved in 2021 before and after completion of both buildings. Assumptions made by the designers have been compared with real values measured on site giving way to design guidelines addressed to structural designers’ offices. Extracting the relevant information from the recorded data is not straightforward, as described in this paper, because timber structures are more sensitive than other ones to the contribution of inner walls, façade and foundation to stiffness and damping. | Data Processing to Assess Structural Damping of Tall Timber Buildings | 10.1007/978-3-031-39109-5_65 |
2023-01-01 | Purpose The present work examines the influence of additional moderate amplitude high-frequency (HF) excitation on energy harvesting (EH) in the inertially excited bistable Duffing-type harvester with nonlinear damping. Method By introducing the slow and fast time scale we split the dynamics of the electromechanical system and obtain the effective hardening mono-stable potential. Results The higher power output was found analytically in the main resonance area of the slow dynamics effective system. In addition, numerical simulation is conducted to support the analytical predictions. Conclusions The excited high-frequency components change the properties of the dynamic solution, transforming it from a double-well to a single-well in the original system, providing an opportunity to study the phenomenon of vibrational resonance as a useful energy mechanism. | Effect of High-Frequency Excitation on a Bistable Energy Harvesting System | 10.1007/s42417-022-00562-4 |
2023-01-01 | Friction dampers are classically used in turbomachinery for bladed discs to control the levels of vibrations at resonance and limit the risk of fatigue failure. It consists of small metal components located under the platforms of the blades, which dissipate the vibratory energy through friction when a relative displacement between the blades and the damper appears. It is well known that the shape of such component has a strong influence on the damping properties and should be designed with a particular attention. With the arrival of additive manufacturing, new dedicated shapes for these dampers can be considered, determined with specific numerical methods as topological optimisation (TO). However, the presence of the contact nonlinearity challenges the use of traditional TO methods to minimise the vibration levels at resonance. In this work, the topology of the damper is parametrised with the moving morphable components (MMC) framework and optimised based on meta-modelling techniques: here kriging coupled with the efficient global optimisation (EGO) algorithm. The level of vibration at resonance is computed based on the harmonic balance method augmented with a constraint to aim directly for the resonant solution. It corresponds to the objective function to be minimised. Additionally, a mechanical constraint based on static stress analysis is also considered to propose reliable damper designs. Results demonstrate the efficiency of the method and show that damper geometries that meet the engineers’ requirements can be identified. | Shape Optimisation for Friction Dampers with Stress Constraint | 10.1007/978-3-031-04086-3_10 |
2023-01-01 | The article proposes a new integro-differential equation describing long-wave dynamics in a layer of a heavy fluid with nonzero vorticity and a free surface. In the limit of infinitely long waves, the system of conservation laws for the integro-differential equation transforms into the system of conservation laws for the Benny equations, which also describe the motion of a fluid with a free surface. Investigation of the solutions of the obtained equation in the linearized case made it possible to reveal the universality of the proposed equation and obtain very delicate results showing the connection between the wave dynamics of an incompressible fluid and the propagation of electrostatic waves in an electron plasma, namely, to find an analogue of Landau damping in plasma in a vortex fluid. A new dispersion relation is obtained for long waves in a vortex liquid, which generalizes the dispersion relation of a plasma with a self-consistent field to the case of a liquid with a free surface. | Long Wave Dynamics in Heavy Wave Gravitating Fluid in Vlasov Type Model | 10.1007/978-3-031-11051-1_100 |
2023-01-01 | Active damping is commonly implemented to stabilize the LC-type voltage source inverter (VSI). Based on previous work, the effective stable region of traditional inductor-current feedback active damping control is narrow. In addition, the system cannot remain stable when f _ r is close to f _ s /6. In order to explore the reason behind this instability phenomenon, the open-loop transfer function derived from z-domain model is attained. It is confirmed that when f _ r is equal to f _ s /6, the contradiction between the crossing of −180° line and unstable poles of open-loop transfer function cannot meet the Nyquist stability criterion. Under this situation, lag compensation methods based on digital filters can be employed to reshape the open loop phase. In this paper, two different digital filters are proposed and assessed. Compared with notch filter, all-pass filter can provide more adjustable lagging phase and stability margin which can guarantee the system to satisfy the requirements of stability. Accordingly, all-pass filter is selected as the solution to reshape the phase. Finally, experimental results provided verify that the proposed method can stabilize the operation of the inverters when f _ r fluctuates around f _ s /6. | A Lag Compensation Method Based on All-Pass Filter | 10.1007/978-981-99-0631-4_78 |
2023-01-01 | Base isolators are devices that provide rapid damping of the energy of dynamic loads such as earthquakes. In this study, the energy absorption performance of a seismic isolator to be placed on the base, in the direction of allowable displacement, was investigated by transmitting various earthquake loads to a rigid structure model that behaves as one degree of freedom. For this purpose, the base isolator with a 30 cm displacement limit at low and high damping ratios relative to each other has been optimized for optimum structural vibration control. In the optimization process, the damping ratio and period of the isolator were made with the Flower Pollination Algorithm to minimize the maximum acceleration and displacement. Critical earthquake analyzes were made within the earthquake excitations, and the control efficiency was compared in low and high-damped isolators. When the results are examined, it has been determined that both low and high-damped isolator systems provide a very close reduction in total acceleration, while the high-damped system performs approximately 10% better in reducing displacement. | Optimum Design of Base Isolation Systems with Low and High Damping | 10.1007/978-981-99-1435-7_24 |
2023-01-01 | In the problems of damping vibration, the question often arises on the practical implementation of damping actuators. The damping efficiency is considered for a console beam described by a linear viscosity Bernoulli–Euler model. The article presents the methods of damping transverse vibrations implemented by a dynamic damper from a piezoelectric layer distributed symmetrically along the axis of symmetry of the beam. Piezoelectric layers with a triangular and rectangular shape of electrode plates are considered, which affect the nature of mechanical stresses upon application of electrical voltage. The electrode plates are thin layers made of nickel or silver several microns thick and located normal to the polarization axis, that is, along the length of the piezoceramic plate. The control of the piezoelectric layers is realized by changing the potential difference between the electrode plates, while the piezoelectric material uncoated by the electrode plate on both sides is useless to use as an active material. In turn, mathematical models of the effect of piezoelectric elements on the cantilever beam are derived from the Hamilton principle. The Pareto-efficiency of quenching by piezoelectric plates with different electrode shapes is evaluated relative to two criteria: the level of control voltage and the maximum deflection of the beam. Also, for a more general analysis, the quenching efficiency is also given for a beam with a piezoelectric plate applied along the entire length and an electrode layer. In addition to Pareto sets, efficiency is also considered in a more applied and particular example—time history. It is worth noting that the synthesis of Pareto-optimal controls is based on the Germeier convolution, and the search for optimal feedback is based on the application of the theory of linear matrix inequalities and effective algorithms for solving them. | Active Damping of Transverse Vibrations of Console Beam by Piezoelectric Layer with Different Electrode Shapes | 10.1007/978-3-031-22093-7_14 |
2023-01-01 | Precast RC structures are commonly adopted for industrial and commercial buildings, to build huge spaces with limited costs and construction times. Due to the lack of efficient seismic regulations until recent times, and adequate assessments of seismic hazard, a huge number of seismically inadequate precast RC buildings are spread through Southern Europe territories. Workers’ and users’ safety requirements, and the preservation of high-value facilities and stocks, demand the adoption of effective retrofit techniques for earthquake risk mitigation. For this structural typology, connections between structural elements are often crucial for carrying lateral loads, such as earthquakes. This study presents an innovative device that acts as beam-to-column joint and as damper at once, with bidirectional dissipative capacity. Very easy to install, low cost and reusable after the main shock, this novel Bidirectional Rotation Friction Damper (BRFD) has been conceptualized and designed to improve the seismic performance of such structures by excluding the brittle failure of structural and non-structural elements. Preliminary experimental tests performed at the University of Ferrara, Italy, have proved the high-damping capacity of this novel device. BRFD effectiveness on a precast structure has been explored using nonlinear time-history analysis accounting both low- and high-intensity Italian earthquakes. Numerical modelling has shown that no beam’s slippage on column top section and no column crisis can occur in both building directions when BRFD are properly implemented. The designed devices provide a global improvement of the seismic performance of the building, preventing any structural and non-structural damage even for the more critical Near-Field events. | A Novel Friction Damper for Seismic Retrofit of Precast RC Structures with Poor Connections | 10.1007/978-3-031-32519-9_140 |
2023-01-01 | This paper presents an assessment of the cable-stayed system (Parallel-strand stay, PSS) and cable damping system used on the Russky Bridge, the determination of the force acting on the bridge cables, and a comparative analysis of the PSS used on the Russky bridge across the East Bosphorus in Vladivostok, each strand of the PSS stay cable is fully independent. This principle has several advantages, including: individual installation and tensioning of each strand; individual corrosion protection; individual removal and replacement when appropriate, and NEW-PWS stay cables. The Japanese cable-stayed NEW-PWS is the next step forward, perhaps even more rational, and efficient for cable-stayed bridges. The transverse responses create significant bending moments in the stiffening beam, and the dynamic deflection angles of the cables begin to play a significant role. This simply cannot be ignored when designing cable-stayed bridges, although these issues have not yet been sufficiently studied. The Russky Bridge is a unique structure, and engineering solutions applied during its construction are a new contribution to the development of not only domestic but also global bridge construction. | Assessment of the Cable-Stayed and Cable Damping System Used in the Russky Bridge and Determination of the Force Acting on the Bridge's Cables | 10.1007/978-3-031-21219-2_304 |
2023-01-01 | Because of the growing demand for high-speed rail vehicles and the ongoing development of these vehicles, the comfort and safety of passengers have become key criterion for advancement. The critical speeds of various DOFs with respect to suspension properties like stiffness and damping are first formulated, then calculated, and then assessed based on its dynamic equations in order to understand, investigate, and improve the ride stability of rail vehicles. To develop, research, and enhance the ride stability of rail cars, this is done. The secondary lateral damping is the most sensitive sort of suspension damper, according to studies employing dynamic equations. This kind of dampening contributes to the stability and ride comfort of rail vehicles. | Formulating and Analysing the Effect of Suspension Parameters on Critical Speeds for Various DOFs in Rail Vehicle | 10.1007/978-981-99-3033-3_66 |
2023-01-01 | Shockwaves are traffic pulses that mainly propagate upstream of traffic flow; commonly found on highways. The phenomenon is created due to the fact that vehicles move at different speeds and many drivers tend to change their speed abruptly; resulting to a temporary limited length tail. This can be damped or prevented using Connected Intelligent Transportation Systems (C-ITS). It is possible to damp or avoid shockwave formations by transmitting relevant on time messages to drivers, which will suggest optimal driving behaviours. In this direction, a method for damping/avoiding traffic pulses (shockwaves) is developed and presented in detail in this paper. After analyzing traffic data from the Attikes Diadromes S.A. highway, Artificial Neural Networks (ANNs) were developed and trained to detect incidents when there is a high probability of shockwave formation. The ANNs were evaluated with real-world data from video analysis. In view of the evaluation, an optimal ANN for detecting shockwaves and an optimal ANN for detecting shockwave forerunners are proposed. The messages to be sent to drivers when detecting such incidents were analyzed. Final messages are proposed based on the available technology and equipment. Next, the C-ITS architecture is developed to support the above services. It was ascertained that the developed ANNs detect shockwaves and shockwave forerunners very efficiently based on specific Key Performance Indicators (KPIs). When the detection is made, the relevant messages are transmitted to drivers in real time. The impact of shockwave preventing and damping messages can be tested through pilot activities. | Using C-ITS for Shockwave Damping and Preventing on Highways | 10.1007/978-3-031-23721-8_43 |
2023-01-01 | This paper presents a method for numerical solution of differential equations of motion of a nonideal gyroscopic rigid rotor with nonlinear cubic damping and nonlinear cubic stiffness of an elastic support in the case of unknown characteristics of the energy source. The essence of the method is that the excitation source characteristic is replaced by its expression found from the frequency equation of forced stationary oscillations under the assumption that the angular acceleration is many times smaller than the square of the angular rotation speed, replacing the angular rate of stationary rotation by a derivative of the shaft rotation angle. The results of the numerical solution are in good agreement with the results of the analytical solution of the nonlinear differential equations of motion, also the results of direct simulation of the rotor system motion when the force source characteristic is unknown and the direct current motor rectilinear characteristic are close to each other. Numerical dynamic analysis confirms that the amplitude of near-resonance oscillations is suppressed by combined linear and nonlinear cubic damping. The method is designed for solution of the first approximation and for weak nonlinear oscillations in the resonance region, where the shaft rotation speed is of the order of natural frequency of the oscillating system. | Resonant Oscillations of a Nonideal Gyroscopic Rotor System with Nonlinear Restoring and Damping Characteristics | 10.1007/978-3-031-29815-8_32 |
2023-01-01 | The article is devoted to resonance reduction during excavator operation due to the rational choice of the bucket and the rotor design parameters, which in turn leads to reliability and durability increase. It is shown that in order to prevent both complete and incomplete resonances during the operation of a bucket wheel excavator, the modes of its operation should be chosen so that the values of forced vibration frequency arising during the rotor operation and the frequency of the “rotor-boom” system natural vibrations are mutually prime numbers. The issue of rational choice of digging modes is considered, which significantly reduces the likelihood of resonance during a trench excavator operation. They developed a method to calculate non-repeating intervals between the rotor buckets, based on the theory of rows. The equality of the intervals leads to the constancy of forced vibrations and can cause resonance. The technique is performed and illustrated by calculations for two options: for the rotors with odd and even number of buckets. | Bucket and Rotor Design Parameter Selection According to Digging Uniformity Condition | 10.1007/978-3-031-14125-6_82 |
2023-01-01 | Chatter is a critical factor that impacts both the efficiency and quality of the milling, and the process damping can suppress its occurrence. Process damping is caused by the interference between the machined surface and the flank face of the tool, which is manifested as an effect on the damping term of the system. In this paper, a method of applying additional vibration for workpiece is proposed, and the influence of additional vibration on process damping and milling stability boundary is studied. The calculation and simulation show that the proposed chatter suppression method is reasonable, and applying appropriate additional vibration can make the milling stability boundary higher and improve the machining efficiency. | Research on the Milling Process Damping and Stability Considering Additional Vibration | 10.1007/978-981-99-6480-2_29 |
2023-01-01 | The purpose of this study was to investigate the small-strain shear stiffness and strain-dependent dynamic properties (i.e., shear modulus degradation curve) of mixtures of gravel and recycled granulated tire rubber for use in geotechnical applications, including geotechnical seismic isolation foundation systems for buildings. Therefore, bender element and small-strain cyclic triaxial tests were carried out on dried specimens of pure gravel and gravel-rubber mixtures with 10, 25, and 40% rubber content by volume. In this paper, the small-strain shear stiffness ( G _max) characteristics as well as shear modulus ( G ) versus shear strain (γ) amplitude curves are presented, and the effects of stress level and rubber content are discussed. Hence, an analytical hyperbolic model for estimating G as a function of the rubber content, stress level, and shear strain amplitude is proposed for gravel-rubber mixtures (GRMs). | Small-Strain Shear Stiffness and Strain-Dependent Dynamic Properties of Gravel-Rubber Mixtures | 10.1007/978-981-99-1579-8_36 |
2023-01-01 | Vibration will lead to power grid disconnection, equipment rupture and other problems, so the working status of the vibration sensor hanging the grid is closely related to the normal operation of the power grid. But there are few researches on the status evaluation of the vibration sensor. On this basis, this paper selects spring-mass-damping system to simulate the sensor, and the classical mechanics is used to deduce the differential equation of the sensor under the system. By the equation, the corresponding transfer function can be established and replaces the sensor to simulate the actual sensor’s work in Simulink, which can provide the sensor work data used for algorithm validation. In addition, the platform simulation interactive interface with the Simulink is established by the APP Designer. In the test section, wavelet is selected for the pre-analysis, and the test is further completed by the BP neural network and Support Vector Regres sion. The simulation platform built can simulate the common status faults of the vibration sensor, and evaluate the status in the platform to test the effectiveness of the status evaluation algorithm. | A Simulation Platform for Assessing the Status of the Vibration Sensor Hanging the Grid | 10.1007/978-981-99-0451-8_37 |
2023-01-01 | The magneto-rheological (MR) damper is one of the most sophisticated applications in the field of semi-active control devices. Its popularity is growing on a daily basis as a result of its numerous benefits and diverse applications. When the viscosity of the MR damper's internal MR fluid is changed, the force delivered by the MR damper changes. Most MR damper modeling and simulation have been completed without much experimental study, which has been accomplished by taking fundamental factors into account. The performance of a small-scale MR damper designed and manufactured was tested experimentally using an MTS servo-hydraulic 311.31 system. To accurately characterize the MR damper behavior, it was tested experimentally for two different displacements at different excitation frequencies. The forces developed by the MR damper, as well as the relationship between governing frequency, velocity, displacement, and maximum energy dissipation by the MR damper, have been studied and presented in this paper based on experimental findings. | Experimental Investigation on Small-Scale MR Damper with Frequency Variation for Seismic Resistant Structure | 10.1007/978-981-99-1608-5_14 |
2023-01-01 | Dynamical and structural systems are susceptible to sudden excitations and loadings such as wind gusts, blasts, earthquakes, and others which may cause destructive vibration amplitudes and lead to catastrophic impact on human lives and economy. Therefore, various vibration absorbers of linear and nonlinear coupling dynamics have been widely studied in plenty of publications where some have been applied in real-world practical applications. Firstly, the tuned-mass-damper (TMD), the first well-known linear vibration absorber that has been well-studied in the literature and applied with various structural and dynamical systems, is discussed. The linear vibration absorbers such as TMDs are widely used in real-life small- and large-scale structures due to their robust performance in vibration suppression of the low natural frequency structural modes. However, the TMD performs efficiently at narrowband frequency range where its performance is deteriorated by any changes in the frequency content in the structure and the TMD itself. Therefore, the targeted-energy-transfer mechanism which is found to be achieved by nonlinear energy sinks (NESs) has ignited the interest in passive nonlinear vibration suppression. Unlike TMDs, the NESs are dynamical vibration absorbers that achieve vibration suppression for wide range of frequency-energy levels. Given the very rapid growth in this field and the extensive research studies supporting the robustness of the NESs, this paper presents the different types of NESs and their applications with main emphasis on the rotary-based and impact-based NESs since they are of high impact in the literature due to their strong nonlinear dynamical behavior and robust targeted energy transfer. | A review on nonlinear energy sinks: designs, analysis and applications of impact and rotary types | 10.1007/s11071-022-08094-y |
2023-01-01 | The effect of novel negative stiffness and inerter-based damper (NSID) for seismic response control of elevated liquid storage tanks is investigated. Liquid storage tanks form important structures that must stay in working condition during earthquakes. Herein, NSID is employed as a supplemental damper to elevated liquid storage tanks. The tank’s continuous liquid mass is represented as two lumped masses: sloshing mass and rigid mass. The tank wall and liquid mass specifications are used to compute the stiffness constant related to these lumped masses. Time history analysis is carried out under real earthquake records to investigate the performance of NSIDs as supplemental dampers. The differential equations of motion are written in state-space form. The NSID parameters are subjected to a parametric analysis, and the best parameters are identified. Response quantities like base shear, liquid sloshing displacements, and rigid mass accelerations are controlled efficiently using the NSIDs. | Seismic Response Control of Elevated Liquid Storage Tanks Using Negative Stiffness and Inerter-Based Dampers | 10.1007/978-981-99-1608-5_44 |
2023-01-01 | In order to enhance the serviceability of civil structures during seismic action base isolators and dampers need to perform at high efficiency independent of the ground shaking level. However, base isolators and dampers are commonly designed to the shaking level of the Design Basis Earthquake (DBE) whereby their efficiencies are poor for earthquakes with lower peak ground accelerations (PGAs). This shortcoming can only be improved if the friction of curved surface sliders is not constant and if hysteretic dampers can produce hysteretic behaviour at various yielding levels. This article presents two new types of curved surface sliders and hysteretic dampers which operate at high efficiency over a wide range of PGAs. This makes it possible to enhance structural serviceability for weak and frequent earthquakes and ensure structural safety for strong motion earthquakes. The dynamic behaviours of the new adaptive curved surface slider and hysteretic damper types are presented. The isolation performance computed by non-linear time history analysis confirms their improved functioning. | Improved Structural Serviceability and Seismic Protection by Adaptive Isolators and Dampers | 10.1007/978-3-031-21187-4_55 |
2023-01-01 | The paper presents the use of semi-active magneto-rheological (MR) dampers for the structural response reduction of the reinforced concrete (RC) elevated liquid storage tanks. The effectiveness of MR dampers is investigated based on the control strategies and the placement of the dampers in the staging. The RC elevated liquid storage tank is modeled as a multi-degree freedom system for the staging with a two-mass model for the container with liquid. Two control systems, viz., open-loop and closed-loop control systems are considered. The control algorithms employed are (1) Passive-OFF, (2) Passive-ON, (3) Clipped-Optimal Control (COC), and (4) Simple Semi-active Control (SSC). The study is also focused on the effect of change of voltage on the response quantities. For the COC algorithm, the feedback gain is obtained by considering velocity feedback. The present study proposes a SSC algorithm which is an effective way of controlling the response of RC elevated tank, which uses the ratio of the damper force and capacity of the damper. For numerical simulation, a code is developed in MATLAB. The coupled differential equations of motion for the system are solved using the state-space method. The response of the broad and slender tanks is studied by taking the ratio of the height of the liquid to the radius of the container ( S ) as 0.5 and 2.0, respectively. The controlled response of the tank under eight different ground motions comprising of near-field and far-field components of earthquakes is evaluated and compared with that of the uncontrolled response. Base shear, displacement, and damper force are obtained. The results showed that the structural response is effectively controlled using semi-active MR dampers with the proposed SSC strategy. The simple semi-active control algorithm proposed in this study could be considered as a proficient algorithm for the seismic response reduction of RC elevated liquid storage tanks using SAMRD. | Seismic Response of RC Elevated Liquid Storage Tanks Using Semi-active Magneto-rheological Dampers | 10.1007/978-981-19-2145-2_79 |
2023-01-01 | Additive manufacturing (AM) offers unique capabilities to incorporate the effects of different mechanics. Traditionally, AM parts are fabricated to reduce weight while maximizing strength. More recently, it has been observed that AM can also be used to fabricate components with internal particle dampers through the process of leaving a small pocket of unfused powder during the printing process. This small pocket of unfused powder can assist in eliminating unwanted vibrations in parts without the post-processing involved with traditional particle dampers. Previous works have reported on the damping capability of various AM designs. Those works focused on a narrow range of excitation amplitudes, over which approximately linear behavior was observed. This work reports on a study of damping capability over a much wider range of excitation amplitudes. Over this wider range, nonlinear behavior was observed. These results indicate certain pocket configurations and modes result in a system regime such that the response amplitude does not exceed a threshold value, up to a certain system excitation. This trend directly translates into an increasingly damped system as excitation increases to a certain level. Other configurations and modes result in a typical single DOF oscillator FRF, while the damping is dependent on the amplitude of the base excitation. Through further experiments, it was determined that there are certain ranges of base excitation that result in consistent nonlinear responses while other ranges result in a response similar to that of a linear system. These results suggest that a system intentionally designed to operate in scope of the nonlinear region may have significantly higher vibration reduction than was thought possible based on previous works. | Experimental Observations of Nonlinear Damping of Additively Manufactured Components with Internal Particle Dampers | 10.1007/978-3-031-04086-3_14 |
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