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2024-01-01 | Passive energy damper systems have been considered as efficient and practical method to improve seismic behaviour of structures under lateral loads including seismic. In this study, a new passive steel damping system with shear mechanism fuse has been proposed. Design procedures, recommended equations, parametric and analytical studies on this novel system were provided for strengthening and retrofitting purposes of reinforced concrete moment frames. Finite element modelling of flexural behaviour, shear and axial failures of concrete and steel members were conducted by fiber model techniques. Non-linear analysis was conducted to evaluate seismic performance, hysteresis response and stability, controlled damage and guided yielding, stiffness and ultimate strength, ductility, and energy dissipation of this system in comparison with the moment frame. Analytical results explained the proposed damping system improved seismic performance of reinforced concrete moment frame, whilst increased stiffness, strength, energy dissipation by increasing damping in non-linear phase and ductility of structure at the same time. This proposed damping system can be easily replaced after severe earthquakes when it is damaged. This study seeks to promote using this damping system because of its ease of construction, availability, affordability, and economical aspect as well as its seismic performance. | Analytical study on seismic strengthening of reinforced concrete frame equipped with steel damping system with shear mechanism fuse | 10.1007/s42107-023-00820-0 |
2024-01-01 | The silt in the Yellow River flood field exhibits strong water sensitivity and unique mechanical properties, which makes it vulnerable to vibration load. This study investigates the dynamic elastic modulus and damping ratio characteristics of the silt by considering the influence of confining pressure and saturation through dynamic triaxial tests. Test results indicate that the backbone curves of the silt are consistent with a typical hyperbolic relationship. The dynamic elastic modulus sharply decreases and eventually tends to stabilize with increasing dynamic strain. Furthermore, the dynamic elastic modulus gradually increases with an increment in confining pressure and decrement in saturation, while the damping ratio simultaneously decreases. A binary linear equation can conveniently estimate the dynamic elastic modulus at a small strain. Based on quantitative analyses, a modified Hardin-Drnevich model is preliminarily proposed to calculate the dynamic elastic modulus and damping ratio of the silt. This investigation supplies a theoretical reference for the engineering construction of the Yellow River basin. 黄泛区粉土水敏感性强, 力学性质独特, 易受振动荷载的影响。本文通过循环三轴试验, 研究 固结围压和饱和度对黄泛区粉土动模量、阻尼比特性的影响。研究结果表明, 黄泛区粉土骨干曲线符 合双曲线关系;随动应变的增大, 黄泛区粉土动弹性模量先急剧减小而后逐渐趋于稳定; 随固结围压 的增大和饱和度的减小, 粉土动弹性模量逐渐增大, 阻尼比则逐渐减小; 二元线性方程可用于估算最 大动弹性模量随固结围压和饱和度的变化规律, 修正Hardin-Drnevich 模型可较为准确预测黄泛区非饱 和粉土的动弹性模量和阻尼比。本研究可为黄河流域工程建设提供理论支撑。 | Dynamic modulus and damping ratio characteristics of unsaturated silt in the Yellow River flood field | 10.1007/s11771-023-5455-9 |
2024-01-01 | Fibers extracted from the fruits of plants are less investigated for engineering applications as composites along with the engineering polymers. This study holistically developed less explored palmyra fruit fiber/polyester composites with or without montmorillonite nanoclays inclusions. Fibers extracted from the Palmyra fruit through special process were either untreated or chemically surface treated to improve interfacial bonding via mechanical anchoring matrix into fiber surfaces for mechanical strength. Fiber composites were manufactured through compression molding route, and the nanoclays are dispersed into the matrix before being compressed. The effects of various surface treatments on the chemistry and morphology of fibers were studied using scanning electron microscopy and Fourier transform infrared spectroscopy. The effect of fiber surface treatment and nanoclay incorporation on free vibrational behavior concerning the natural frequency and damping factor was also examined. Free vibration tests reveal that fiber surface treatment substantially impacts the natural frequency and damping factor of palmyra fruit fiber-reinforced composites (PFFCs). Specifically, NaOH-treated PFFCs have the maximum flexural strength, corresponding to the highest natural frequency. In addition, introducing nanoclays increases the flexural modulus beyond that of original PFFCs. After fiber surface treatments and the addition of nanoclays, modal analysis revealed the increase in composite stiffness through the changes noted in the composite damping results. | Synergistic effect of fiber surface treatment and nanoclays on the damping behaviors of polyester composites reinforced with palmyra fruit fibers | 10.1007/s00289-023-04722-8 |
2024-01-01 | The damping performance of chlorinated butyl rubber (CIIR) cannot satisfy the rigorous requirements of damping and vibration reduction. Hindered phenol can endow rubber composites with good damping performance, but these small molecules may migrate from rubber matrices. Here, a novel type of damping agent based on the hyperbranched polyester grafted hindered phenol (AG-HP102) was prepared by grafting hindered phenol (AG) with hydroxyl terminated hyperbranched polyester (HP102). It was then incorporated into chlorinated butyl rubber (CIIR) to prepare damping rubber composites. The test results showed that tan δ _max of CIIR/AG-HP102 (7 phr) was 1.40, which was 32.1% higher than that of pure CIIR, 1.05. In addition, the glass transition temperature ( T _g) was increased from − 26.0 to − 16 ℃. The mechanical property tests showed that the tensile strength and elongation at break of the CIIR/AG-HP102 (7 phr) composite reached 8.21 MPa and 1192%, respectively, which was 290.9% and 39.5% higher than those of pure CIIR, 2.11 MPa and 858%. These experiment results can offer some useful information for the design and fabrication of high-performance polymeric damping materials. | Structure and properties of damping chlorinated butyl rubber composites with hyperbranched polyester grafted hindered phenol | 10.1007/s00289-023-04777-7 |
2024-01-01 | This work examines dynamic characteristics of a cable-stayed bridge, utilizing acceleration data from the bridge deck as well as the cables. A weather station installed on the bridge provides additional data for the interpretation of the observed wind and traffic induced vibrations. The measurement data are acquired on the Stavanger City Bridge. The bridge layout, combining steel and concrete girder segments supported by a tower and stay cables, makes it an interesting case for system identification analysis especially as all three parts of the bridge structured are monitored to some extent. Especially as cable vibration sensors are rarely included in long-term wind and structural health monitoring of the cable-stayed bridges. The data analysis investigates the characteristics of the suspended steel box and the supporting concrete girder, synchronization in response between the different structural components and the interaction between deck vibrations and cable vibrations. The paper explores the performance of system identification techniques for estimation of damping, which is challenging for damping levels as low as 0.05%, such as in the case of the stay cables. It is found that there is a strong interaction between the cables and the deck structure. Detailed identification of the cable properties showed a clear dependency between the total cable damping and the wind velocity, revealing the contribution of aerodynamic damping. | Field Observation of Global and Local Dynamics of a Cable-Stayed Bridge | 10.1007/978-3-031-47152-0_6 |
2024-01-01 | In recent years, there has been several research describing the influence of elastic elements, such as springs or flexible polymers, on the damping of pressure pulsations. As pressure pulsations are one of the most inconvenient phenomena occurring in positive displacement compressor installations, experimental studies of various elastic elements produced with 3D printing techniques were carried out. The research focusses on the description of the relationship between the geometrical parameters of the printed springs and their impact on the pressure pulsations in the installation. The presented studies are basically preliminary studies that allow to estimate the possible direction of further development of such methods in the field of pressure pulsation damping. | Influence of 3D Printed Elastic Structures on the Pressure Pulsations in the Reciprocating Compressor Manifold | 10.1007/978-3-031-42663-6_35 |
2024-01-01 | Using spiral tube damping busbar is a promising method for VFTO suppression due to its effectiveness and ease of installation. To optimize the suppression effect, it is crucial to deeply understand the suppression mechanism and related factors. Thus, a complete circuit model of the damping busbar is established, including all stray parameters and impedance. The method to calculate stray inductance and capacitance between the shell and busbar under high frequency VFTO is introduced. The completely circuit model is established based on SF6 breakdown criterion. The model is applied to a 550 kV GIS platform, and the effect of circuit parameters on suppression is analyzed. Results indicate that the stray capacitance between the busbar and shell also significantly affects VFTO rejection, in addition to coil inductance and shunt capacitance. | Research on Full-Circuit Model of Damping Busbar for VFTO Suppression | 10.1007/978-981-99-7401-6_22 |
2024-01-01 | Pressure pulsations and pipeline vibrations are unfavorable phenomena generated by the periodic operation of the volumetric compressors. The variable speed of the compressor shaft generates pulsations and vibrations of different frequencies, which means that Helmholtz resonators and tuned mass dampers are not the most effective devices to reduce these phenomena. One of the possibilities to dampen pulsations in a wide range of frequencies, is to place shaped nozzles in the compressor discharge manifold. However, the nozzles significantly affect the compression power by restricting the flow from the wall to the centre of the pipe. Therefore, the influence of elements placed on the axis of the pipeline with spherical shapes was investigated. In this research, 3D-printed nozzles with a different numbers of spheres were tested. Research shows how a number of spheres in the array influence the damping of pressure pulsation and pipeline vibration. | In-Line Sphere Arrays as Pressure Pulsation and Pipeline Vibration Dampers in Reciprocating Compressor Manifold | 10.1007/978-3-031-42663-6_50 |
2024-01-01 | In this work, the vibrational behavior of luffa cylindrica/USP composites has been addressed. The effect of fiber dosage with difference fiber content from 30, 40, 50% and chemical treatment (NaOH) are analyzed. The specimens are fabricated with compression molding technique with pressure of 17 MPa. For the production of composite specimens, untreated and NaOH treated fiber were used as reinforcement and unsaturated polyester resin (USP) used as matrix. The prepared specimens are cut as per the ASTM standard, and mechanical and vibrational tests were conducted. The experiential nodal analysis is used to fine the natural frequency and damping of the composites. The results depicts that the increase in fiber dosage started to improve the mechanical properties of the composite beam. The NaOH treatment showed the improvement in mechanical and damping of the composites. The 50% fiber dosage showed the good tensile and flexural properties of the composites. The interfacial mechanism of the composites was interpreted in the SEM. | Effect of Fiber Dosage and Chemical Treatment on the Vibrational Behavior of Luffa/ USP Composite | 10.1007/978-981-99-8327-8_15 |
2024-01-01 | In this work, irreversible energy transfers from a linear oscillator (designated as “primary structure”) forced by shock to a strongly nonlinear attachment composed of particle impact dampers (PIDs) are investigated. The attachment is in the form of a rigid cavity filled with differing quantities of granules; the elastoplastic collision modeling the granule-to-granule and granule-to-cavity interactions adopts a Hertzian contact law in the axial direction and a Coulomb slipping friction law in the tangential direction. The discrete element method, capable of simulating convergence and accurate energy conversion, is utilized to simulate the strongly nonlinear dynamics of the PIDs. Of specific interest are the irreversible energy transfers from the primary structure to the PIDs and the dependence of these transfers on the specific PID configurations. It is concluded that, for the same number of granules in the PID, drastic differences in energy transfer exist depending on the initial topology of the granules. To this end, symmetric and asymmetric topologies in which clearances are introduced are proposed for the considered PIDs. In addition, the effect of the size of the PID cavity is studied, and interesting correlations between irreversible energy transfer and granular dynamics are revealed. Accordingly, energy transfer for granular motions in the gas regime is less effective compared to a collect-and-collide regime, which leads to significant energy transfer. The perspective of irreversible energy transfers reported herein provides strong motivation for developing the next generation of PID technology. | Irreversible energy transfers in systems with particle impact dampers | 10.1007/s11071-023-09007-3 |
2024-01-01 | Friction-based dampers have gained attention as a cost-effective way to provide structural control during natural hazards. However, the dry friction interfaces in these systems result in a highly nonlinear damping response during the reversal of damper travel, termed damper backlash. Moreover, the stick-slip phenomena intrinsic to the sliding response of dry friction interfaces make the accurate modeling of friction-based structural dampers challenging. Dynamic friction modeling for structural dampers currently relies on analytical models to approximate the damper’s response at a current location given the damper’s state and average out the complex system responses during travel reversal or stick-slip movement to obtain a model of the system’s performance. In this chapter, we propose the use of a deep learning model to capture the temporal dynamics of the system that when combined with the LuGre friction model provides a physics-informed machine learning approach for inferring the damping force of a dry friction interface given the state of the model. Specifically, this chapter uses a long short-term memory model to infer the LuGre friction model’s parameters. A methodology for parameter identification using truncated backpropagation through time is given, which allows for real-time updating. Model validation is performed using a 9 kip rotary friction damper designed for high damping performance and mechanical simplicity. The model is validated with data from real natural hazard events and used in a real-time hybrid simulation. The performance, reliability, and accuracy of the deep-learning-based friction model are discussed. | Deep-Learning-Based Friction Modeling of Dry Interfaces for Structural Dampers | 10.1007/978-3-031-36663-5_27 |
2024-01-01 | Different from the undamped counterpart, nonlinear elastic waves exhibit different wave motion behavior and mechanisms when propagating in damped nonlinear diatomic acoustic metamaterials (NDAMs). Propagation characteristics of elastic waves in a damped NDAMs have not well been studied in the literature. This paper constructed a nonlinear wave propagation model of the damped NDAMs to investigate effects of the inherent damping of a nonlinear system on wave propagation characteristics of the damped NDAMs such as wave attenuation and gain characteristics. Frequency-domain dispersion relations are calculated to study the new nonlinear wave propagation characteristics in the damped NDAMs with different nonlinear parameters based on the analytical formulation. Furthermore, both of acoustical and optical wave-mode are considered to investigate the time-domain spatial propagation characteristics of nonlinear traveling wave packets in the damped NDAMs by use of the spectral-spatial analysis approach with results show that localization feature emerged in the damped NDAMs. Influences of damping ratio and geometry parameters on the spatial propagation characteristics in the damped NDAMs and results show that solitary waves are exhibited in damped NDAMs due to nonlinear interactions of dispersion relations and nonlinearity, which demonstrates that one can tune theses parameters to control nonlinear wave propagation in the damped NDAMs. These new phenomena have some potential applications in energy harvesting and acoustical functional devices. | Research on new wave behavior and mechanisms in nonlinear diatomic acoustic metamaterials with linear damping | 10.1007/s11071-023-09058-6 |
2024-01-01 | Seismic performance of Y-braced frame with double round steel tube aims to study the performance of the Y shaped bracing in a frame under seismic forces. The project involves the designing of the double round steel tube which act as a damper in the frame. The optimum size of the damper or the double round steel tube is to be identified by varying the dimensions in terms of height, thickness, diameter and length. Any one of the parameters is changed keeping all others constant to find the better resulting one. All most 20 combinations were done to find the optimum sized one. Optimization aims to achieve the best yielding damper to be placed. After optimization, the performance of the damper under seismic load is analyzed. The evaluation includes analysis and result comparison of the frame with and without double round steel tube. The finite element analysis software ANSYS is used to find the optimum size of damper and analyze the frames. | Seismic Performance of Y-Braced Frame with Double Round Steel Tube | 10.1007/978-3-031-39663-2_30 |
2024-01-01 | We study impact of water-glycerol droplets on a flexible surface, in particular the effect of viscosity on the overall system’s dynamics. We experimentally analyzed the impact dynamics and cantilever response of the system. A thin hydrophilic cantilever beam, made of copper, was used as a flexible substrate. During impact, the viscosity of a droplet damps the substrate’s vibration by dissipating the system’s energy. However, we observed that the initial dynamics of the droplet also contribute to the damping of the cantilever. An analytical model was presented to predict the motion of a cantilever beam, which was shown to be in good accord with our experimental findings. | Droplet Impact on a Hydrophilic Flexible Surface | 10.1007/978-981-99-7047-6_26 |
2024-01-01 | When the maglev train with a speed of 600 km/h runs at high speeds, the vertical carriage vibrations caused by irregularity of tracks are intensified, affecting passenger comfort and even safety. Therefore, it is necessary to find new damping devices to reduce carriage vibrations. Magnetorheological fluid dampers have advantages such as continuously adjustable damping, low-power consumption, high damping force output, and fast response speed. This paper firstly discusses the feasibility of applying magnetorheological fluid dampers to the secondary suspension system of maglev vehicles. It investigates the working mode, installation position, and stroke of magnetorheological fluid dampers for high-speed maglev trains. Based on a simplified suspension model for maglev trains, a magnetorheological fluid damper control system based on fuzzy logic is designed. The effectiveness of the proposed semi-active secondary suspension system based on magnetorheological fluid dampers is verified through numerical simulations, demonstrating its ability to effectively improve the vibration reduction performance and ride comfort of maglev trains. | Design and Vibration Control of Secondary Suspension for Maglev Train Based on Magnetorheological Fluid Damper | 10.1007/978-981-97-0554-2_54 |
2024-01-01 | Damping devices installed in building structures increase resilience against natural hazards such as earthquakes and high winds. Structural control devices are divided into passive, semi-active, active, and hybrid systems. Semi-active vibration control has received considerable attention because it combines the reliability of passive control systems with the versatility to adapt like active systems but with a smaller magnitude of power consumption. Among semi-active devices, variable-friction dampers are promising because they only require a variable clamping force to a surface to dissipate mechanical energy into heat. Factors that drive the adoption of new technology in structural engineering are driven by cost saving, ease of use, technology effectiveness, and reliability of response. Based on these design goals, this research focuses on the design and characterization of semi-active cam-lever friction damper devices. The proposed device applies a normal force to frictional surfaces through slipping bolts that are attached to a cam-double-lever mechanism. This configuration consists of a cam-lever that has a varying radius cam attached to a lever and a slider-crank mechanism that transforms the rotational movement of the first lever into a linear movement of an actuator. This provides a large mechanical advantage to easily adjust the position of the levers and change the tension of the slipping bolts. The feasibility of this device is studied with a small-scale prototype using additive manufacturing of components and an Arduino microcontroller to change the position of the levers. The device is installed in a single-DOF structure that is subjected to harmonic motions and earthquakes using a shake table. The results show that the mechanical advantage and the speed of response of the system are a function of the geometry of the components of the cam-levers. It is also shown that the slipping bolts can have a minimum pre-tension to make the device work as a passive device if the actuation system fails. This initial pilot study opens pathways in advanced mitigation strategies for smart structures. | Development of Semi-active Cam-Lever Friction Device on a Small-Scale Structure Subjected to Earthquake Loads | 10.1007/978-3-031-36663-5_28 |
2024-01-01 | Tuned mass dampers (TMDs) are proven to be effective in reducing both the acceleration and displacement responses of civil structures subjected to earthquake. The basic idea behind the use of a TMD in civil structures is to create an alternative path for the flow of mechanical energy in the dynamic system of primary structure to deviate the input seismic (or wind) energy from entering its key structural components such as beams and columns. This is achieved by storing and dissipating the input seismic energy in the TMD itself as it oscillates with the vibration of primary structure. The process of energy dissipation in the TMD can be carried out using solid friction by allowing the mass of TMD to slide over a surface attached to the primary structure rather than using viscous damping that is usually provided by viscous fluid dampers connecting the mass of TMD to the primary structure. The former method is relatively simpler to implement and it has a lower cost of installation, operation, and maintenance as well. A TMD that uses friction for energy dissipation is termed as frictional TMD (FTMD). Although the energy dissipation mechanism of FTMD is simple and cost-effective, it is susceptible to stick-slip motion, a highly nonlinear phenomenon occurring at low velocities when the dynamic state of moving mass abruptly shifts from the sliding phase to the sticking phase or vice versa. In particular, during the sticking phase when the mass of FTMD sticks to the friction surface, the FTMD can neither store nor dissipate the input seismic energy. The objective of this chapter is to study how stick-slip motion can affect the energy dissipation capability a FTMD and the seismic performance of primary structure. For this purpose, a 3DOF dynamic model is employed to model the interaction of FTMD with the primary structure (two-story base-isolated building) during the stick-slip motion. The friction force is described by a modified version of the Karnopp friction model in which a sticking velocity is defined to characterize the boundary between the sticking and sliding phases and perform a parametric nonlinear time-history analysis of 3DOF dynamic model. The numerical results show that for a given ground motion acceleration it is feasible to adjust both the mass of FTMD and the normal force in such a way that the intensity of ground motion remains above the breakaway level to avoid sticking, allowing the FTMD to slides continuously during the earthquake. | Vibration Control Using Frictional Tuned Mass Dampers with Stick-Slip Motion | 10.1007/978-3-031-36663-5_29 |
2024-01-01 | Active systems have garnered interest from researchers worldwide for their fascinating displays of congregations and the far-reaching scope of biomimetic applications. The current chapter talks about one such application: the use of active particles to induce mixing in a stratified passive system. Simulations using a Langevin model in two dimensions shows the mixing state of the initially stratified system reach a saturation point in finite time. Interestingly, with change in the number of active mixers, only the rate of mixing is found to be affected, while the final mixed state is perceived to be almost similar. Active particles numbering not more than 20% of that of the passive species is found to be enough to induce brisk mixing. An investigation is parallelly carried out into the maximum rotation allowed for each active mixer to maximise the overall mixing effect. The objective of this discourse is to provide a numerical backbone to the feasibility of the use of micro/mini robots for mixing of living/non-living entities, while also discussing the factors affecting the process. | Activity-Induced Mixing in a Stratified Binary Passive System | 10.1007/978-981-99-5752-1_11 |
2024-01-01 | Optimization on rotor-dynamics has increasingly attracted attention from numerous researchers, although concentrations on the optimization of time-invariant system parameters result in relatively low versatilities. In this paper, a multi-objective optimization framework based on a novel predictive control method is proposed for rotor systems with active dry friction dampers. Instead of optimizing normal forces of friction dampers as most current researches do, we optimize the controller parameters instead to improve optimization efficiency. The predictive controller, incorporated with the augmented Kalman filter, is inserted into the non-dominated sorting genetic algorithm II to accomplish the multi-objective optimization. To validate the efficacy of the optimization procedure, numerical investigations are performed for a rotor system with two active friction dampers. Results demonstrate that the proposed control method can reduce the rotor vibration significantly after optimization with constraints on equivalent stiffnesses of the friction dampers, and it is superior to traditional direct optimization methods when the optimization on a specific system with different unbalance levels is considered. | Multi-objective Optimization of Active Dry Friction Damper-Rotor Systems Based on Predictive Control | 10.1007/978-3-031-40459-7_20 |
2024-01-01 | In this chapter, an attempt is made to develop a coupled non-linear turbulence-structure-damper model in a Finite Volume-Finite Difference (FV-FD) framework. A Tuned Liquid Damper (TLD) is used as the additional damping system along with inherent structural damping. Real-time simulation of flow-excited bridge box girder or chimney section and the vibration reduction using TLD can be performed using the developed model. The turbulent flow field around a structure is modelled using an OpenFOAM transient PISO solver, and the time-varying drag force is calculated. This force perturbs the structure, causing the sloshing phenomena of the attached TLD, modelled using shallow depth approximation, damping the flow-induced vibration of the structure. The structural motion with and without the attached TLD is modelled involving the FD-based Newmark-Beta method using in-house MATLAB codes. The TLD is tuned with the vortex-shedding frequency of the low-Reynolds number flows, and it is found to be reducing the structural excitation significantly. On the other hand, the high-Reynolds number turbulent flow exhibits a broadband excitation, for which by tuning the TLD with few frequencies obtained through investigations, a good reduction in vibration is observed. | Reduction in Turbulence-Induced Non-linear Dynamic Vibration Using Tuned Liquid Damper (TLD) | 10.1007/978-981-99-5752-1_18 |
2024-01-01 | Traditional methods of protecting structures from the destructive forces of nature, appearing during earthquakes, based on the strengthening of structures, lead to a significant increase in the cost of construction in seismically hazardous areas. Rolling bearings, limited by various surfaces of rotation as the main element, are used in many seismic and vibration protection devices. In this work, random oscillations of a vibration-protected body on vibration supports with straightened surfaces are studied. Within the framework of the theory of Markov processes of non-linear mechanical systems, the Fokker-Planck-Kolmogorov (FPK) equations for the amplitude probability density describing the oscillatory movements of a vibration-protected body on vibration supports with straightened surfaces are compiled, taking into account rolling friction on relaxing soils under random kinematic influences such as “white noise”. Solutions are obtained in stationary and non-stationary formulations. The probabilistic characteristics of the amplitude of random vibrations of a vibration-protected body are determined. | Oscillations of a Body on Rolling Bearings with Straightened Surfaces Caused by a Random Movement of the Base | 10.1007/978-3-031-45709-8_85 |
2024-01-01 | Tapered laminate structures with ply drop-off are used extensively in aeronautic and astronautic applications. However, ply drop-off involves inherent structural discontinuities that create stress concentrations, potentially resulting in failure below the loading capability of the structure. We performed experiments to study the mechanical properties of a tapered laminate structure in the movable wing skin of an aircraft, and examined the effects of fatigue and damp-heat exposure on such properties. The mechanical behavior and failure modes of the structure were simulated using finite element analyses and compared with the experimental results. The experimental findings were found to agree satisfactorily with the simulation results. This study provides useful information to support the design and production of such composite structures. | Mechanical Properties of a Tapered Composite Structure in a Movable Aircraft Wing | 10.1007/978-981-99-8864-8_37 |
2024-01-01 | The seismic performance curve of single-particle-system is used to investigate the damping amount of additional dampers for reinforced concrete frame structures. The damping amount of the additional metal damper is researched and calculated. First, the original structure is simplified to a single-particle-system. The inter displacement angle of the structure is calculated according to the response spectrum. Then the target interlayer displacement angle of the original structure is set, the damping of the single-particle-system is calculated according to the target interlayer displacement angle. Finally, the damping amount of the multi-particle-system is derived from the damping amount of the single-particle-system, and the damping amount of the additional metal damping required for the multi-particle-system structure is calculated. The time history analysis of seismic response of the calculation model is carried out by Wilson-θ method, and the response value is obtained. At the same time, the hysteretic curve of the damper under earthquake action is drawn, the energy dissipation capacity of the damper is researched by the hysteretic curve. Some considerations are put forward for the design of reinforced concrete energy dissipation frame structures in the future. | Analysis of Energy Dissipation Structure of Reinforced Concrete Frame with Additional Metal Damping | 10.1007/978-981-99-6368-3_29 |
2024-01-01 | The Church of the Transfiguration is a Catholic Basilica located on top of Mount Tabor in Galilee, Israel. It was built in 1924 following the design of the Italian architect Antonio Barluzzi on the ruins of an ancient Byzantine church (4th-6th century) and of a Crusader church (12th century). The façade of the church is characterised by two twin towers, connected by an arch supported by two columns. Bells are located only inside the South Tower. An extended crack pattern affected the Bell Tower, caused by the dynamic actions of the bells, transferred through the existing steel bellframe rigidly connected to stone masonry walls. A Finite Element Model of the Bell Tower has been implemented in order to evaluate its structural behaviour and dynamic response to static and dynamic loading. The model has been calibrated using a dynamic identification test, to identify the main frequencies of the tower, considering its particular external restraint conditions, due to the presence of the church in the North-East corner and of the arch in the North-West corner. The study allowed the design of the new steel bell frame, which has been equipped with damped support, in order to reduce the forces transferred to the masonry walls by the bells’ movement. The stiffness of the damped supports has been carefully investigated to avoid resonance phenomena with the natural frequencies of the tower. After the completion of the restoration works and of the mounting of the new bell frame, a new dynamic test has been carried out in order to confirm the numerical model design results. | Experimental and Numerical Studies on the Bell Tower of the Transfiguration Basilica on Mount Tabor, Israel | 10.1007/978-3-031-39603-8_62 |
2024-01-01 | To deal with vehicle/track interaction in the time domain, the infinitely long railway track often has to be truncated, generating a finite track model. The ends of the rail in the model are normally simply supported. To account for high-frequency vibration, high train speed and the presence of multiple carriages, the track model must be long, demanding too much computational effort. Means is required to shorten the track model. Aiming at this, the track is divided into three parts, a left semi-infinite part, a middle part (the track model) and a right semi-infinite part. The left and right parts are assumed to be two semi-infinite periodic tracks. The semi-infinite periodic track is replaced with an equivalent mass-spring-damper system. The mass-spring-damper system is determined in such a way that it provides the same receptance to the track model as the semi-infinite periodic track. The receptance of the semi-infinite periodic track is calculated from the response of the two semi-infinite periodic tracks joined together as an infinite periodic structure subject to specific harmonic loads. | Boundary Condition and Equivalent Mass-Spring-Damper System for a Truncated Railway Track | 10.1007/978-981-99-7852-6_21 |
2024-01-01 | A computer algorithm is developed for the numerical simulation of fluid viscous dampers (FVDs), represented by a Maxwell model in elastic and inelastic SDOF systems for nonlinear dynamic analyses under near-field (NF) and far-field (FF) earthquake motions. Maxwell model incorporates the frequency dependence of the damping and stiffness coefficients observed in the fluid orifice of FVDs, which is characterized by three basic parameters (supplemental damping ratio $${\xi }_{add}$$ ξ add , velocity power $$\alpha $$ α , and axial stiffness $${k}_{s}$$ k s ). The computational efficiency of the algorithm is verified against experimental example in previous research. This study shows the effect of NF and FF on energy dissipated by FVD ( $${E}_{d2}$$ E d 2 ) with varying system ductility level µ , $${\xi }_{add}$$ ξ add and $$\alpha $$ α . The selection procedure of axial stiffness ( $${k}_{s}$$ k s ), based on energy-dissipated spectra, is proposed in this study to obtain the optimal values of $${k}_{s}$$ k s in extensive response history analyses of SDOF systems. It is found that the $${k}_{s}$$ k s size of FVD is more significant to structural properties (natural vibration period $${T}_{n}$$ T n , and µ ), and FVD characteristics ( $${\xi }_{add}$$ ξ add and $$\alpha $$ α ). | Maxwell Model of Fluid Viscous Dampers in Elastic and Inelastic SDOF Systems | 10.1007/978-981-99-3362-4_39 |
2024-01-01 | The present work aims to analyze the effectiveness of a passive vibration control device in a structure subjected to random vibrations. The structure is a ten-story building equipped with a Tuned Mass Damper (TMD) at the top and it is subjected to artificial seismic excitations generated by the Kanai-Tajimi spectrum. The uncertainties present in both the systems and excitation parameters are taken into account. Thus, mass, stiffness and damping of the structure and the TMD, as well as peak ground acceleration (PGA), ground frequency and ground damping ratio are assumed as random variables, and the problem is solved via Monte Carlo Simulation. The study uses Newmark's numerical integration method to obtain the results of displacement, velocity, acceleration and maximum interstory drift values of the structure. The results obtained during the study demonstrate that the variance decreased and the dynamic response of the structure in terms of interstory drift is considerably reduced by about 55% after installing the TMD at the top of the building. | Dynamic analysis of a building equipped with a Tuned Mass Damper subjected to artificial seismic excitations considering uncertainties in the parameters of the structure and of the excitation | 10.1007/978-3-031-47036-3_8 |
2024-01-01 | Background Acoustic metamaterials exhibit many novel wave propagation behaviors that can be designed to control and guide wave propagation in a variety of media. Due to the existence of damping, the attenuation effect of wave propagation significantly affects the elastic wave propagation in the nonlinear system. However, nonlinear wave propagation mechanisms in nonlinear damped acoustic metamaterial systems are largely unexplored. Purpose Therefore, it is extremely necessary to reveal unique nonlinear wave propagation behaviors in nonlinear acoustic metamaterials with damping. Methods In this paper, spectro-spatial analysis method is adopted to study propagation characteristics of nonlinear traveling wave packet in space- and time-domain. Results Numerical simulations demonstrate that influence of nonlinearity on dispersion relation will gradually disappear with time lapse for the nonlinear damped acoustic metamaterial systems, which indicates remarkable wave propagating decay in a nonlinear damped acoustic metamaterial system. The wave packets generated in nonlinear damped acoustic metamaterial systems have solitary waves caused by the interaction between dispersion, and nonlinearity exists in the nonlinear systems. Conclusions A possibility of tunable wave propagation characteristics is shown in the nonlinear damped acoustic metamaterial systems by selecting different value of damping coefficient. This study indicates that different wavelength region can affect existence of solitary waves on acoustic- and optical-mode wave packets in the damped acoustic metamaterial systems. | Spectro-spatial Analysis of Nonlinear Wave Propagation Behaviors in Damped Acoustic Metamaterial Systems | 10.1007/s42417-022-00827-y |
2024-01-01 | Semi-active control is considered to be very interesting in view of its similarity with the active control, however, requiring significantly lesser control-effort/input. Indeed, semi-active control strategies have been used quite widely in many vibration control applications over the past years. In the present study, a magnetorheological (MR) damper is taken as the damping device, which is used to produce the control force (through modulating its damping coefficient with the help of an external input voltage) in the semi-active framework to mitigate seismic vibration. The MR damper is well-known for its mechanical simplicity, lower power consumption, and large force capacity. The Bouc–Wen hysteresis model is taken into account for understanding the mechanical behaviour of MR damper and to calculate the control force. The widely used control strategy, viz. linear quadratic Gaussian (LQG) control, is incorporated in this semi-active control problem to generate the desired control force. The seismic vibration may cause considerable damage to a structure. In the present investigation, a three-storey building structure is considered for the demonstration of control-performance. It is observed that the semi-active control strategy has been able to perform quite satisfactorily (in mitigating the seismic vibration) with quite insignificant control-effort (in terms of supplying the electrical voltage of an insignificant range from 0 to 5 V). | Semi-active Control for Seismic Vibration Mitigation of Building System with Magnetorheological Damping Device | 10.1007/978-981-99-6855-8_2 |
2024-01-01 | Completing a long-term project characterizing squeeze film dampers (SFDs) for air breathing engines, the paper presents complete measurements of the forced performance of an elastic structure hosting an OR-sealed damper (OR-SFD) and the identification of physical parameters, namely stiffness and damping, for the dry structure, the ORs, and the lubricated OR-SFD. The damper with slenderness ratio L/D = 0.2 and radial clearance c ~ 0.002 D is lubricated a light oil supplied at 0.69 bar(g). Shakers produce circular whirl motions of the test system with amplitude r = 0.05 c to 0.45 c and frequency $$\omega$$ ω = 10 Hz to 70 Hz (max. Squeeze velocity v _ s = r $$\omega$$ ω =55 mm/s). The ORs force coefficients are a function of the orbit amplitude and nearly invariant with frequency. The ORs centering stiffness quickly decreases with amplitude, likely due to the extensive deformation and slow elastic recovery in the ORs’ material bonds. As the whirl amplitude grows, the ORs viscous damping ( C _ OR ) reduces from 10% to 3% of the lubricated system damping. For small orbit radii, r ≤ 0.25 c, the SFD added mass ( M _ SFD ) and viscous damping ( C _ SFD ) coefficients approach predictions for a fully sealed damper. For moderate size orbits ( r = 0.45 c ), M _ SFD drops by 75% and C _ OR decreases by ~ 40% due to persistent air ingestion for motions with v _ s > 24.5 mm/s. Videos show a bubbly mixture in the return line and also through the damper top end exposed to ambient. Over a certain elapsed time, a simple procedure draws into a deflated balloon the material contents in the film. The novel approach estimates the gas volume fraction (GVF) that rapidly increases as v _ s grows. The findings quantify the deterioration of ORs force coefficients, their inability to keep the lubricant sealed, and their limited ability to prevent persistent air ingestion into the film land. | Dynamic Performance of an O-Ring Sealed Squeeze Film Damper and a Simple Way to Estimate the (Ingested) Gas Content in a Squeeze Film | 10.1007/978-3-031-40455-9_9 |
2024-01-01 | To solve the excessive vibration of an energy storage flywheel rotor under complex operating conditions, an optimization design method used to the energy storage flywheel rotor with elastic support/dry friction damper (ESDFD) is proposed. Firstly, the dynamic model of the ESDFDs-energy storage flywheel rotor coupling system is established by using the finite element method. Secondly, through variables sensitivity analysis, support stiffness, support position, shaft stiffness and the position of flywheel are determined as design variables. Then, the optimization objective function is constructed by comprehensively considering critical speed constraint, influence factors of mode unbalance, proportion of strain energy and energy consumption rate of damper. Finally, the improved particle swarm optimization is used to optimize the design of the energy storage flywheel rotor with ESDFDs. The results show that the damping performance of the ESDFDs increase by 25%-40% and the unbalance sensitivity of rotor decreases compared with initial model, and it indicates the optimization design of the energy storage flywheel rotor with ESDFDs is effective. | Vibration Reduction Optimization Design of an Energy Storage Flywheel Rotor with ESDFD | 10.1007/978-3-031-40459-7_7 |
2024-01-01 | In order to solve the rail corrugation in the curved section of the steel spring floating slab track in Qingdao metro, a new type wide-frequency tuned mass damper (WTMD) was developed, which integrated the labyrinth restraint damping plate and TMD’s technology. The track tests of the rail corrugation, rail vibration, interior noise, trackside noise were conducted before and after the WTMDs installation. After the study, the following three conclusions can be drawn: (1) Three times corrugation track tests show that the corrugation develops slowly at 1 month and 4.5 months after the installation of WTMD, and the corrugation is invisible. (2) After installing WTMD, the vertical and lateral vibration of the rail are 10% of the original, and the total rail vibration level will be reduced by 8.1 dB and 10.7 dB respectively. (3) The trackside noise, the passenger interior noise and the driver interior equivalent A-weighted noise overall levels decrease by 9.0, 7.7, and 5.8 dBA, after the WTMDs installation. It can be seen that, the installation of WTMDs can effectively reduce the rail vibration, inhibit the rail corrugation, and also play a good role in reducing the trackside noise and the interior noise. | Study on the Wide-Frequency Tuned Mass Damper Inhibiting Rail Corrugation and Noise in Floating Slab Track | 10.1007/978-981-99-7852-6_37 |
2024-01-01 | Motorcycle experiences different vibrations on different road conditions. In order to improve the problem that the classical control algorithm cannot perfectly balance the driving comfort and road-holding performance when the motorcycle is driving in different road conditions, the hybrid control algorithm based on frequency division (HCFD) is designed. Firstly, the single-axis two-degree-of-freedom suspension model of motorcycle semi-active suspension system (SASS) and the look-up table model of solenoid valve damper are established. After that, the classical SASS control algorithms such as skyhook and groundhook are analyzed. HCFD is designed and verified for its inability to perfectly balance the comfort and road-holding performance of motorcycle. Finally, a real motorcycle experimental platform is built using the rapid control prototype (RCP) based on dSPACE, and the HCFD is tested and verified on washboard roads. The experimental results show that the SASS using the HCFD not only enhances driving comfort but also effectively mitigates concerns related to a decline in road-holding performance. The HCFD has practical significance to improve the comprehensive performance of motorcycle SASS. | Control algorithm design of motorcycle semi-active suspension system via frequency division | 10.1007/s12206-023-1204-0 |
2024-01-01 | Components manufactured by laser powder bed fusion (LPBF) additive manufacturing can have particle dampers designed into the part by leaving unfused powder inside a defined pocket of the part during manufacturing. These pockets of unfused material have inherent damping capabilities that suppress the vibrations and potentially reduce component wear. Particle dampers have been shown to be a simple and effective way to increase the damping of a structural component manufactured by LPBF; however, the compressing effects of the particle damper pocket inside the beam have not been studied. The amount of unfused powder inside the pocket is difficult to control (or even measure) during manufacturing; therefore, this study reports preliminary investigations on the effects of energy absorption provided by changing the volume of the pocket. In this study, beams are printed with 316L stainless steel powder with single particle dampers. Thereafter, the cover of the pocket is deformed, decreasing the volume of the pocket. The energy absorption characteristics of the particle damper are quantified. The unfused powder pocket’s damping characteristics are assessed by observing the structure’s response to various excitation methods. An input-output relationship can be deduced using a reference accelerometer and an accelerometer mounted passed the damper pocket with respect to the fixity. With this relationship established, the magnitude of damping and the phase attributed to it is determined. Studying the damping characteristics of various compressed pocket sizes and powder quantities will provide helpful information to enhance particle dampers’ efficiency using LPBF techniques. | Investigating Compressing Particle Damper Pockets in Beams Manufactured by Laser Powder Bed Fusion Additive Manufacturing | 10.1007/978-3-031-37007-6_15 |
2024-01-01 | A collaborative optimization methodology is proposed for estimating the parameters of magnetorheological (MR) dampers in structural control systems. By integrating the characteristics of antlions and ant colonies, this method aims to improve the estimation process through teamwork. Ants and antlions communicate and work together to find the optimum solution. Cooperative communication and information exchange between ants and antlions are established. Ants share pheromone information and discover paths with the antlions, guiding their pit-building strategies and decision-making. Antlions, in turn, share their findings, such as successful traps or promising regions, with the ants. This collaboration creates a symbiotic relationship, benefiting from each other's discoveries and optimizations. The collaborative nature of the algorithm enhances exploration and exploitation of the solution space and improves estimation accuracy and convergence speed. The efficiency of the algorithm is shown using experimental simulations and comparative analysis. The results showcase its superiority in accurately estimating the parameters of MR dampers, thereby enhancing the performance of structural control systems. | Antlion-Facing Ant Colony Optimization in Parameter Identification of the MR Damper as a Semi-active Control Device | 10.1007/978-981-99-7227-2_8 |
2023-12-29 | In this paper, we investigate the stabilization of Timoshenko systems with or without Kelvin–Voigt damping, in the presence of second sound. We have drawn conclusions that provide new insights into the effect of local Kelvin–Voigt damping. Our primary conclusion is that the exponential stability of the system achieved through local thermal damping will be destroyed by the local Kelvin–Voigt damping with a discontinuous coefficient at the interface. In particular, when local dissipation solely originates from the second sound, the system exhibits exponential stability. However, when Kelvin–Voigt damping is introduced into the local thermoelastic component, the system, surprisingly, loses its exponential stability. In this case, the corresponding solution decays polynomially with the rate $$t^{-2}$$ t - 2 . | Effects of Kelvin–Voigt Damping on the Stability of (Thermo)Elastic Timoshenko System with Second Sound | 10.1007/s00245-023-10098-y |
2023-12-28 | In the midst of escalating seismic activity on a global scale, the imperative of devising ingenious structural solutions looms large, driven by the necessity to safeguard the security and soundness of constructed environments. This study delves into an inventive avenue for bolstering seismic resilience, by ingeniously merging hydraulic dampers (HD) into mass–spring–damper (MSD) systems through a configuration referred to as the integrated damper arrangement. This integration unfolds through the strategic placement of an HD at the centre of the spring of MSD system, optimizing the system's parameters via the dynamic optimizer Particle Swarm Optimization (PSO) method, emulating the PSO-derived output using MATLAB simulations and for best-of-best results assisted by Artificial neural network (ANN). In structure, building integrated systems work to protect the moments of tuned mass damper (TMD) system in their position and control the structural vibration to absorb the decapitated energy for proving stability. The central thrust of this research paper orbits around the ratio of both the systems that are combined and intricately integrated with their relevant parameters. This convergence of efforts culminates by ANN in peak displacement values of 0.7930 m and peak velocity reaching 1.7615 m per second. This study also establishes a seamlessly integrated system and a meticulously crafted analytical formula to govern this combined system, merging the worlds of structure and mechanics with precision in their application. | Unveiling advanced modelling and analysis: the integrated system and formula for mass–spring–damper with hydraulic damper systems | 10.1007/s41939-023-00317-y |
2023-12-27 | This paper presents the evaluation of the dynamic stiffness coefficient (the stiffness and damping coefficient) of a rigid and massless foundation embedded in a layered elastic half-space. Linear hysteric material damping is introduced in the model using the correspondence principle. Based on the strength of the material approach with one-dimensional wave propagation in cones (cone model), horizontal and vertical dynamic stiffness coefficients were evaluated. To check the accuracy of the model, the dynamic stiffness coefficient of foundations resting on and/or embedded in layered half-space was evaluated using a cone model and validated with published results based on rigorous analysis. A parametric study is also carried out to investigate the influence of shear wave velocity, depth of embedment, and thickness of the top layer on the dynamic response of the foundation embedded in layered half-space. The results of the cone model analyses are presented in terms of stiffness coefficient K ( a _ o ) and damping coefficient C ( a _ o ) varying with dimensionless frequency ( a _ o ) for both horizontal and vertical modes of vibration. The results of the cone model provide physical insight with sufficient generality, making it convenient to use for various foundation vibration problems. | Dynamic Response of Embedded Foundations in Layered Halfspace: A Cone Model Approach | 10.1007/s40098-023-00825-1 |
2023-12-27 | The industry’s mechanical equipment often faces a significant demand for damping rubber. Simultaneously improving damping and toughness of rubber materials is a challenging task. It was achieved by incorporating crystal particles into the chlorinated butyl rubber (CIIR) network, inspired by the “sliding crystal mechanism”. To create the elastomers with high damping and toughness, polyurethane was used along with polyethylene glycol as a soft segment. The combination factors, including coordination and hydrogen bonds, played a crucial role in facilitating the formation of crystal particles within the material. These crystal particles acted as rigid fillers, enhancing the material’s toughness. Additionally, the sacrificial reversible bonds present in the crystal particles allowed for energy dissipation during stress. These bonds can be repeatedly broken and regenerated, enabling the material to dissipate energy efficiently. Comparing these elastomers to pure CIIR, they exhibited a tensile strength and elongation at break of 5.76 MPa and 1973%, a fracture energy of 28.73 MJ/m^3, a damping factor of 1.52, and a damping temperature range of 80 °C. These results indicate significant improvements in both damping and toughness properties. This advancement could have valuable implications for the industry’s mechanical equipment, which often relies on effective damping rubber. | Toughening and damping elastomers using crystallizable polyurethane particles | 10.1007/s00289-023-05116-6 |
2023-12-21 | Granular materials used for vibration reduction often show dense granular clusters in engineering practice. Nevertheless, there are great differences in the damping effect between different dense granular clusters. In this work, discrete element simulations are performed to investigate the evolution of dense granular cluster in dissipation behavior by vertically vibrating a quasi-2D granular container with constant excitation frequency but different excitation amplitude, which reveals nine different granular motion patterns. Simulation results indicate that, with the increase of excitation amplitude, the internal configuration of dense granular cluster in granular container evolves gradually from static-disordered to dynamic-disordered and then dynamic-ordered, and finally becomes loose. The scope of high damping granular phases (HDGPs) is finalized based on the friction dissipation mechanism of granular balls in four dynamic-ordered dense granular clusters, where there may be reversible granular jamming transitions. The universal dynamical behavior of dense granular clusters in HDGPs is revealed, which contributes to obtaining the optimal granular damping effect by controlling the motion pattern of vibrated granular materials. Graphical abstract | From solid-like to floating: evolution of dense granular cluster in dissipation behavior | 10.1007/s10035-023-01385-0 |
2023-12-18 | Background Eddy current damper (ECD) pledges better control over damping coefficient, provides contactless damping, requires little or no maintenance, has simpler construction, no performance degradation over time, and is cost-effective as compared to mechanical dampers. Its challenge includes the development of a system which provides comparable damping density to other mechanical systems for structural applications. Purpose ECD has the potential to protect common structures in seismically active areas at low cost and with better vibration control. Further, the application of such dampers may protect industrial assembly structures against undesirable fatigue and increase the lifespan of structures that are constantly prone to vibrations. Methods This paper produces a review of existing literature in vibration control of structures equipped with ECDs, types of ECDs developed for structural applications, SDOF (single degree of freedom) benchmark structure equipped with ECD, challenges, and opportunities in the development of ECD therein. | Research Developments of Eddy Current Dampers for Seismic Vibration Control of Structures | 10.1007/s42417-023-01229-4 |
2023-12-18 | A semilinear beam/plate equation with non-constant material density in the context of energy damping models is considered. Well-posedness and asymptotic behavior of solutions are established. The main result deals with the existence of a compact global attractor for the proposed problem. | Dynamics for a class of energy beam models with non-constant material density | 10.1007/s00033-023-02147-x |
2023-12-16 | Purpose The active tuned mass damper (ATMD) system is underactuated where the number of actuators is less than the number of system’s DOF. It is well known that the regulation of an underactuated system is challenging. Few reports can be found in the literature relating to the design of ATMD systems from the view point of their underactuated dynamics. In this paper, we firstly clarify the underactuated behavior of an ATMD system whose ill-conditioned controllability matrix largely limits the flexibility of controller design. Controllers are proposed to circumvent the underactuated dynamics to ensure vibration attenuation during the earthquake and rapid state convergence in the ATMD when the earthquake vanishes. Methods This paper proposes a redefined output function to destroy the underactuated dynamics so that a stabilizing controller can be designed to regulate the new output. A low pass filter is suggested in the control loop to give boundedness of primal and auxiliary systems simultaneously supported by BIBO stability. Results The simulation results show that the proposed ATMD design can give much better performance in both time and frequency responses compared with the traditional TMD design under the 1940 El Centro earthquake and 1985 Mexico City earthquake. Conclusion The proposed output redefinition design removes the underactuated dynamics in the ATMD system effectively, and the low-pass filter inclusion preserves system passivity so that convergence of the states can be obtained. These have been justified by mathematical proofs and simulation verifications. | Vibration Suppression in the Underactuated Dynamics of ATMD Systems Under Earthquake Excitation | 10.1007/s42417-023-01224-9 |
2023-12-08 | This paper is concerned with the Gromov–Hausdorff stability of global attractors for the 3D Navier–Stokes equations with damping under variations of the domain, which describes the complexity of the dynamics of the motion of a fluid flow. The Gromov–Hausdorff stability accounts for the Gromov–Hausdorff distance between two global attractors which may lie in disjoint phase spaces, as well as the stability of global attractors under perturbations of the domain. The same phase space cannot be used for the convergence via the Gromov–Hausdorff distance, which can be overcome, following Lee et al.(2020), by introducing a Banach space defined on a variable domain without “pull-backing” the perturbed system onto the original domain. | Gromov–Hausdorff stability of global attractors for the 3D Navier–Stokes equations with damping | 10.1007/s00033-023-02146-y |
2023-12-08 | The Wind Farms (WFs) are located far away from the load centres, with the resultant equivalent reactance being more than near the load. It results in a weak grid due to high power transferred in the transmission lines that affect the low frequency of oscillations, and the system exists with undamped functions. The transmission line has to be compensated to transmit wind power effectively. The Static Synchronous Series Compensator (SSSC) connects WF and the load centre. This work demonstrates a Power Oscillation Damper (POD) to WFs and SSSC for transmission lines and their combination. The eigenvalue of the damping ratio and frequency of oscillations are considered objective functions for particle swarm optimization and formulated based on stability to optimize the controller parameter for improving stability. The coordination between the POD and SSSC has been conducted using a Fuzzy Logic Controller (FLC) to further enhance system performance. The small signal and transient stability examinations use eigenvalue analysis and time-domain simulation. It is analysed by varying the length (km) of the transmission line between the WF and the load centre, along with variation in wind penetration. The study observed that small signal stability damped the oscillatory modes most effectively. It is also revealed that the controller's combination with FLC intensifies the capability under extreme disturbances and detects an improvement in the system’s transient stability. The proposed approaches’ effectiveness is evaluated on an IEEE-11 bus two-area test system with optimized controller gain parameters and controller coordinated FLC through a Real-Time Digital Simulator. | Dynamic stability reinforcement in remote wind farm connections: POD-SSSC coordination with fuzzy logic control using RTDS | 10.1007/s00202-023-02145-2 |
2023-12-07 | Robustness is defined as the insensitivity of the structure to uncertainties like earthquakes, fire, cyclones, explosions, tsunamis, etc. Robustness analysis of Kalman observer with robust controller for damped outrigger structure is studied to analyze its design performance in the presence of various effects like an earthquake. This is a novel innovative study undertaken in evaluating the robustness of the proposed controller to signify its performance in the field of structural control. The damped outrigger structure is modeled using the finite element approach by finding mode shapes, fundamental natural frequency, and period. The Kalman observer is modeled according to the requirement of the structure with the Riccati equation. The robust proportional–integral–derivative controller is designed according to the input disturbance with Ziegler–Nichols ultimate gain approach. The issue of deterioration in the system performance due to saturation was observed during the analytical investigation of the robust proportional–integral–derivative controller with Kalman observer, which has been addressed by the anti-windup approach. The robustness index of the structure is calculated using sensitivity and complementary sensitivity. The maximum amplitude ratio of the sensitivity for viscous damper-controlled structure is 1.4723 and the value decreases for the other controllers, with a minimum value of 1.0 for the proposed anti-windup robust proportional–integral–derivative controller with Kalman observer. Respectively, the percentage overshoot for the uncontrolled case is 23.4% that values decreasing for other controlled cases, with a minimum of 7.8% for proposed anti-windup robust proportional–integral–derivative controller with Kalman observer. This robustness index and performance indices discriminate the significant robust performance of the proposed robust proportional–integral–derivative controller with Kalman observer-based damped outrigger structure in comparison with other controlled and uncontrolled cases. | Robustness evaluation of the damped outrigger structure | 10.1007/s40430-023-04584-1 |
2023-12-02 | Vibration problems of mistuned blisks have been extensively investigated in the past several years. To suppress the vibration level of the mistuned blisk, the blisk structure is equipped with piezoelectric shunt damping. At the same time, the performance of the piezoelectric shunt damping can be enhanced through optimization. By optimizing the mistuning modes of resistance and inductance parameters, it can be applied to the blisk structure to obtain a better damping effect. The present study aims to effectively apply the optimization of the piezoelectric shunt damping patches (PSDPs) intentional mistuning mode to the blisk. To achieve this, a semi-analytical model of the mistuned blisk structure with intentional mistuning PSDPs is firstly created for purpose of optimization analysis. Then, based on the deterministic mistuning blisk, an optimization model is established with the objective of minimizing the amplitude amplification factor of the mistuned blisk. The model considered the resistance parameters and the inductance parameters in the shunt circuits as design variables. Taking the mistuned blisk with intentional mistuning PSDPs as an example, it is confirmed that piezoelectric shunt damping effectively suppresses the vibration response of mistuned blisks. Additionally, the correctness of the semi-analytical model used is verified. The multi-population genetic algorithm (MPGA) is used to optimize the intentional mistuning mode of piezoelectric shunt circuits. The results show that the optimized mistuning modes of shunt circuits have a better vibration suppression effect by comparing with tuned circuits and several common circuit mistuning modes, which demonstrates the feasibility and rationality of the optimization model. | Optimization analysis of the intentional mistuning mode of the blisk with piezoelectric shunt damping patches | 10.1007/s40430-023-04583-2 |
2023-12-01 | Cohesive zone model has been used widely in fracture propagations, but few of them have considered strain rate, plastic strain, and variable damping together. In this paper, artificial compliance and spurious oscillation in bilinear cohesive law are investigated through dynamic simulations. Several constitutive laws and damage criteria used in bilinear cohesive law are presented first, and the properties in these constitutive laws are analyzed about deficiency of plastic strain, inherent discontinuity of constitutive law, and inherent discontinuity of force. Two damage evolution methods (effective separation method and damage factor method) are compared, and the latter one that strictly follows damage criterion and has no healing effect is a better choice for damage evolution. Numerical investigations are conducted to help select proper stiffness and to make sure artificial compliance in an acceptable range. Apart from strain rate and plastic strain, variable damping is considered into bilinear cohesive law, which can remove discontinuous force caused by constant damping at the start and end of bilinear cohesive law. One fixed delamination propagation and two free fracture propagation examples are used to verify the methodology proposed in this paper. From the simulation results, the methodology used in this paper removes spurious oscillation caused by constitutive law itself and enables correct force response, and variable damping reduces spurious oscillation. | Improved cohesive zone model: integrating strain rate, plastic strain, variable damping, and enhanced constitutive law for fracture propagation | 10.1007/s10704-023-00723-w |
2023-12-01 | High penetration of inverter-based renewable energy sources (RESs) in the microgrid reduces the system inertia. As a result, sudden load fluctuations or unwanted disturbances in the power network increase the rate of change of frequency and this may lead to system instability. Virtual inertia (VI) controller with energy storage system is generally used to improve system inertia and frequency stability of the microgrid. Existing several VI controllers are able to improve the transient performance of the system, but these solutions come with increased settling time and increased steady-state error. To improve the transient performance, a concept of power injection controller is developed. In this paper, an inertia injection controller based on fractional-order proportional-integral-derivative (FOPID-IIC) is proposed to improve the system transient performance. This controller injects inertia power to the microgrid associated with photovoltaic system to improve transient stability and to reduce settling time. The parameters of proposed controller are optimized by Grey wolf optimization technique. Furthermore, the performance of the proposed controller has been analysed and its superiority has been established compared to conventional VI control methods for different loading conditions considering high RES injection. Effect of nonlinearities like governor dead band, and generation rate constraints on the system performance is also studied. | Grey wolf optimization approach for enhancing the transient stability of microgrid using fractional-order PID-based inertia injection controller | 10.1007/s00202-023-01946-9 |
2023-12-01 | The present work is a fundamental study on added damping regarding shunted inclined piezoelectric sensors for structures on cantilever plates. These structures are subjected to transverse and torsional actuation due to inclined piezoelectric actuators. Estimation of added damping is derived using an energy variation and energy dissipation approach. The model assumes that the structure behaves according to the Kirchhoff plate theory for plates. For torsional modes, the Saint-Venant warping function is included in voltage and added damping estimates. The piezoelectric patch’s location and orientation are important parameters for achieving added damping for a particular mode. The optimal orientation of PZT to achieve maximum added damping for a particular mode may lie at the nodal location of other modes. The estimation of added damping for PZT located at nodal locations for those modes is addressed. The energy dissipation model is correlated and validated on a cantilever plate for $$0^{\circ }$$ 0 ∘ , $$25^{\circ }$$ 25 ∘ , $$45^{\circ }$$ 45 ∘ and $$90^{\circ }$$ 90 ∘ inclined piezoelectric patches. Added damping is studied for the first bending and first torsional modes of cantilever plates. | Study on Prediction of Added Damping from Inclined PZT-5 H for Bending and Torsional Modes | 10.1007/s40997-023-00638-w |
2023-12-01 | In a Hilbert space setting, we consider new first order optimization algorithms which are obtained by temporal discretization of a damped inertial autonomous dynamic involving dry friction. The function f to be minimized is assumed to be differentiable (not necessarily convex). The dry friction potential function $$ \varphi $$ φ , which has a sharp minimum at the origin, enters the algorithm via its proximal mapping, which acts as a soft thresholding operator on the sum of the velocity and the gradient terms. After a finite number of steps, the structure of the algorithm changes, losing its inertial character to become the steepest descent method. The geometric damping driven by the Hessian of f makes it possible to control and attenuate the oscillations. The algorithm generates convergent sequences when f is convex, and in the nonconvex case when f satisfies the Kurdyka–Lojasiewicz property. The convergence results are robust with respect to numerical errors, and perturbations. The study is then extended to the case of a nonsmooth convex function f , in which case the algorithm involves the proximal operators of f and $$\varphi $$ φ separately. Applications are given to the Lasso problem and nonsmooth d.c. programming. | First order inertial optimization algorithms with threshold effects associated with dry friction | 10.1007/s10589-023-00509-9 |
2023-12-01 | A flat bottom tank geometry has traditionally been used for tuned liquid dampers (TLDs) to control the resonant response of tall buildings. However, the bottom geometry may be dictated by building space availability. Different bottom geometries have been proposed to conform to strict floor plans. Previous studies focused on modelling TLDs with irregular bottom geometries have limitations on excitation amplitudes or are computationally expensive. As structures may encounter extreme loading events, understanding the response of TLDs under large excitation amplitudes is imperative. A numerical model capable of accurately capturing the complex response of TLDs with irregular bottom geometries equipped with screens at high amplitude excitations with practical computational power requirements is currently unavailable. This study develops an incompressible smoothed particle hydrodynamics model to simulate any tank bottom geometry with screens macroscopically without the numerical limitations of existing models. The base model is modified to simulate any tank bottom geometry SPH results are found to be in good agreement with existing numerical models at shallow fluid depths and low excitation amplitudes. The response of different tank bottom geometries is investigated under large amplitude harmonic excitation, revealing that curved bottom tanks have higher sloshing response amplitude than sloped and flat bottom tanks. Overall, it was found that the model did not encounter any limitations over the range of parameters considered and, as such, can efficiently (computationally) model TLDs with different tank bottom geometries over a wide range of excitation amplitudes. | Modelling of sloped and curved bottom sloshing tanks with screens using smoothed particle hydrodynamics | 10.1007/s40435-023-01176-8 |
2023-12-01 | Abstract This study aims to investigate the contact performance of non-Gaussian rough surfaces under mixed lubrication conditions, with a particular emphasis on the normal dynamic contact stiffness and damping characteristics. The research employs statistical analysis and modeling techniques to analyze non-Gaussian rough surfaces and combines them with the theory of elastic-plastic fluid dynamic lubrication. The objective is to examine the variations in stiffness and damping during the contact process. Numerical simulations are conducted to explore the impact of factors such as normal dynamic load, lubricant viscosity, operating speed, vibration frequency, vibration force, and non-Gaussian roughness on the normal dynamic contact stiffness and damping at the mating interface. The findings of this research provide valuable insights in advancing the design, analysis, and optimization of sliding guide performance in the field of machine tools. | Investigation of Normal Dynamic Contact Stiffness and Damping Characteristics in Mixed Lubrication for Non-Gaussian Rough Surfaces | 10.3103/S0025654423601337 |
2023-12-01 | Swarm robotics, in which groups of robots coordinate to achieve a common goal, has the potential to revolutionize a wide range of industries. However, one of the key challenges in developing effective swarm systems is enabling the robots to navigate around obstacles while maintaining cohesion. In this article, the problem of trajectory tracking for a self-organized swarm of wheeled robots in the shape of a regular polygon operating in an environment with obstacles is addressed. The goal is for the swarm to follow a reference point by the geometric center of the swarm, while avoiding collision with obstacles and maintaining a given distance between neighboring robots and the reference point. To solve this problem, a method based on virtual forces that act on each individual robot in the swarm is proposed. These virtual forces are derived from virtual spring-damper connections acting from the obstacles, adjacent robots, and the reference point. The virtual forces allow the robots to dynamically adjust their trajectories to avoid obstacles and maintain the shape of the swarm. The proposed approach is evaluated through simulation and experiment with a swarm of two-wheeled robots. During the experiment the maximum deviation of inter-robot distances was equal to 0.08 m. With the set limit distance to obstacles equal to 0.2 m, from which virtual forces start to push the robot away from the edge of the obstacle, the shortest distance to obstacles was 0.11 m. The results demonstrate the effectiveness of the method in enabling the swarm to accurately follow the reference point while avoiding obstacles and maintaining the desired distances between robots. Overall, the approach represents a step forward in the development of virtual force-based algorithms for obstacle avoidance in swarm robotics. | Obstacle avoidance of a wheeled robotic swarm using virtual spring-damper mesh | 10.1007/s40435-023-01173-x |
2023-12-01 | Boring bars with a large length-to-diameter ratio have become increasingly indispensable for deep hole machining. However, the dynamic performance of conventional boring bars may be inadequate, resulting in vibrations. In this paper, a novel boring bar with composites and a constrained layer damping structure was fabricated to suppress vibrations during the boring operation. Initially, the configuration of the CFRP boring bar was proposed based on theoretical analysis, and then the modal parameters were calculated using the bending strain energy method and cantilever beam theory. Subsequently, the geometric design parameters were optimized analytically using the finite element method. Modal and cutting tests were then conducted to evaluate the cutting stability of a CFRP boring bar with a length-to-diameter ratio of 8.4. The modal parameters, vibration signals, and cutting force signals were measured and compared with a carbide boring bar. The experimental results indicated that there was a significant improvement in the cutting stability of the CFRP boring bar. | Analysis and Development of the CFRP Boring Bar for Stability Improvement | 10.1007/s12221-023-00376-5 |
2023-12-01 | To investigate the size-dependent behavior of micro-beams with thermoelastic damping (TED), a new size-dependent thermoelastic damping model based on modified gradient elasticity is proposed in this study. The governing equations and boundary conditions are derived based on the modified gradient elasticity theory and the single-phase-lag thermal relaxation model. By utilizing the complex frequency method, the exact expression of thermoelastic damping is obtained from the model. The results indicate that there is a significant size effect of thermoelastic damping in micro-beams, and the critical thickness of the beam is related to the internal length scale. Different thermal parameters have varying degrees of influence on thermoelastic damping. Compared with other size-dependent thermoelastic damping models, the proposed thermoelastic damping model in this paper is characterized by its clear physical interpretation and simple form. Some theoretical guidance for the designing of high-quality micro/nano-electromechanical resonators can be provided by the new model. | A size-dependent thermoelastic damping model for micro-beams based on modified gradient elasticity | 10.1007/s00419-023-02510-4 |
2023-12-01 | Effects of Hf and Zr additions on microstructure, phase components, structural properties, transformation temperatures and damping capacity of Ni_3Ta high-temperature SMA were studied via SEM/EDX, XRD, DSC and DMA measurements. Microstructural investigations showed that the microstructure of Ni_3Ta contained the Ni_8Ta precipitate, intergranular cracks and large-sized voids. Microstructures of Ni_74.1Ta_25Hf_0.9 and Ni_74.1Ta_25Zr_0.9 (at.%) alloys, on the other hand, consisted of micro-sized (NiTa_2)-based precipitates and large-sized (Ni_2Ta)-based phase regions located along grain boundaries. In addition, eutectic fcc(Ni) + (NiTa_2) phase mixture regions were displayed in the surface regions of Ni_74.1Ta_25Hf_0.9 and Ni_74.1Ta_25Zr_0.9 alloys in bulk form. DSC analysis revealed that transformation temperatures of the Ni_3Ta were altered by the additions of Hf and Zr, resulting in narrowing transformation hysteresis (A_f-M_s) values of the alloys. XRD results demonstrated that there were significant changes in both position and intensities of the characteristic diffraction peaks of the Ni_3Ta alloy with the additions of Hf and Zr. DMA analysis indicated that maximum damping capacity was found to be 0.101 for the Ni_3Ta alloy. However, it was observed that Hf and Zr additions to the alloy caused reducing in their damping capacity to 0.049 and 0.043, respectively. | Effects of Hf and Zr Additions on Microstructure, Phase Components and Martensitic Transformation Temperatures of Ni_3Ta High-Temperature Shape Memory Alloys | 10.1007/s11665-023-07920-7 |
2023-12-01 | Abstract The results of theoretical and experimental studies of rubber-cord shells of rotation of connected couplings are presented. Based on the heat balance equation and the law of distribution of tangential stresses along the forming cylindrical shell, the differential equations of temperature distribution in the rubber-cord and metal parts of the coupling are obtained. The values of the damping coefficients and torsional stiffness of the rubber cord shell are obtained. | Investigation of Temperature Fields of Rubber-Cord Shells of Rotation of Connected Couplings of the Drives of Transport Vehicles | 10.1134/S1052618823080058 |
2023-12-01 | Hybrid journal bearings are used mostly to take benefits of simultaneous hydrostatic and hydrodynamic actions. This paper uses numerical technique to investigate wear effect on the cross-coupled dynamic coeff. and threshold stability speed of recessless conical hybrid journal bearing (CHJB) using capillary restrictor. The developed Reynolds equation describing the streamline incompressible flow, iso-viscous lubricating fluid in the narrow region of conical bearing and journal is resolved by methodology of finite element. Results obtained by numerical simulation reveal the considerable change in the dynamic coeff. and threshold stability speed of worn CHJB as compared to newly installed bearing of matching configuration. | Influence of Wear on the Cross-Coupled Dynamic Coefficients and Threshold Speed of Conical Hybrid Fluid Film Bearing | 10.1007/s40032-023-01000-4 |
2023-12-01 | In this paper, a simplified acoustic optimization method is proposed to replace the sound power with the maximum normal velocity of the surface as a direct target, a topological optimization model of the variable density method is established to reduce the acoustic radiation of the structure, and the relationship between the form of damping distribution and the acoustic radiation is investigated. The complex modulus model is used to describe the viscoelastic material intrinsic relationship of the damping layer. The effects of different excitation frequencies on the topology optimization results are discussed. The radiated noise is simulated using the finite element method and the boundary element method. Five plates are fabricated according to the damping layer layout for different single-frequency excitations. Modal and acoustic experiments are carried out to validate the proposed method. The numerical and experimental results show that there is a significant reduction in the sound pressure level (SPL). | Simplified topology optimization of damping layer in plate structures for vibration and acoustic response | 10.1007/s12206-023-1101-6 |
2023-12-01 | Hybrid vibration absorbers (HVAs) are an effective solution for vibration mitigation. They combine the passive vibration absorption mechanism of tuned mass dampers (TMDs) with feedback-controlled actuators, similar to active mass dampers. This enables them to overcome the performance of both systems in terms of vibration mitigation effectiveness and energy consumption, respectively. This study evaluates the vibration suppression capabilities of an HVA against self-excited oscillations. A single-degree-of-freedom host system encompassing a negative damping term is considered. First, the possibility of enhancing the stability properties of an optimally tuned TMD through a feedback controller is evaluated. The analysis shows that this approach cannot improve the absorber’s performance. Subsequently, simultaneous optimization of all the HVA parameters is considered. Our results reveal that this approach significantly enhances the system’s performance. All analysis is carried out analytically without resorting to approximations. Finally, the absorber is numerically applied to suppress friction-induced vibrations and galloping instabilities. | Hybrid vibration absorber for self-induced vibration suppression: exact analytical formulation for acceleration feedback control | 10.1007/s11012-023-01731-9 |
2023-12-01 | Abstract The influence of internal dissipation on the rotational motion of the Earth in the gravitational field of the Sun and Moon is studied within the model of M.A. Lavrentiev. The averaged equations of second approximation describing the evolution of the Earth’s rotation axis and the magnitude of its angular velocity are obtained. The dependence of the rate of evolution on the values of the model parameters is studied. Phase trajectories of the evolutionary process are constructed for different parameter values. It is shown that the observed drift of the Earth’s magnetic poles can be explained within the framework of a mechanical model by the angular acceleration of the Earth. | Evolution of Rotational Motion of the Planet Earth under the Influence of Internal Dissipative Forces | 10.1134/S001095252370051X |
2023-12-01 | To suppress the vibration of the suspended cab of construction machinery, a novel passive hydraulically damped rubber mount (PHDRM) with multi-inertial tracks is designed. The two suspension system models describing single and multi-inertial tracks are proposed in different coupled relations based on the parallel combination model of rubber and fluid, considering fluid rheological behavior and compressibility. The low-frequency dynamic behaviors of the PHDRM and rubber isolator with corresponding structures under fixed-frequency and frequency-sweep excitations are investigated analytically and experimentally. It is demonstrated that the dynamic stiffness of PHDRM exhibits softening characteristics, as well as amplitude and frequency dependence, which are caused by the viscoelastic behavior of hydraulic oil and fluid-solid coupling. And the damping has a more significant amplitude and frequency dependence. The results also illustrate that PHDRM exhibits more excellent dynamic performance in suppressing vibration and resonance compared to the traditional rubber isolator. The effectiveness of the mathematical model is verified by comparing the simulation and experimental results. Further, the dynamic performances of the PHDRM with different lengths, cross sections, and numbers of inertial tracks are studied by using measured force-displacement loops and transmissibility, and their vibration isolation performances were compared. Experimental results show that the PHDRM with three inertial tracks has significant advantages in energy dissipation, resulting in better predictions in reducing transmissibility. The studies in this paper provide an important theoretical basis and reference value for the structural optimization design of the hydraulically damped rubber mount. | Dynamic performance of a novel hydraulically damped rubber mount with inertial track at low frequency: modeling and experimental study | 10.1007/s12206-023-1109-y |
2023-11-29 | We give a proof of linear inviscid damping and vorticity depletion for non-monotonic shear flows with one critical point in a bounded periodic channel. In particular, we obtain quantitative depletion rates for the vorticity function without any symmetry assumptions. | On the Stability of Shear Flows in Bounded Channels, II: Non-monotonic Shear Flows | 10.1007/s10013-023-00661-z |
2023-11-27 | In this paper, we consider the initial value problem for weakly damped Kirchhoff plate equation with logarithmic nonlinearity in a bounded domain. We investigate the existence, uniqueness and polynomial or exponential energy decay estimates of global weak solutions under initial energy less than the depth of the potential well and some appropriate conditions. Moreover, we derive the finite time blow up of the weak solution with upper bounded initial energy. | Stabilization and blow-up for a class of weakly damped Kirchhoff plate equation with logarithmic nonlinearity | 10.1007/s13226-023-00518-8 |
2023-11-25 | Free vibration, damping and three-dimensional thermal buckling studies of the doubly curved sandwich viscoelastic-functionally graded (FG) material shell panels have been carried out under the high-temperature environments when subjected to uniaxial and biaxial uniform in-plane compressive loading. The sandwich-curved panels used in this analysis comprised of three layers. Base layer of the sandwich is made of aluminum, core layer of soft and thick viscoelastic material and the constraining top skin of FGM having the ceramic–metal (ZrO_2/Ti-6Al-4 V) constituents, to incorporate the constrained layer damping (CLD) in the shell structure. The governing equation of motion has been derived through the Hamilton’s principle along with the finite element method (FEM). The influence of thermal environment or temperature gradient is considered to be imposed on the FGM top layer only, with uniform temperature distribution across the top surface of the layer. Unique temperature-dependent material constants have been considered to determine the influence of high-temperature environments on the three-dimensional thermal buckling response of the sandwich panel. The influence of various system parameters specifically top surface temperature, aspect ratio, shell geometries, core thickness ratio and power law index on the structure’s modal natural frequencies and modal loss factors has been investigated through parametric analyses. Thermal buckling and buckling response of the curved panels with respect to the parametric variations have also been presented subjected to the uniaxial and biaxial loadings. The contribution of FGM constraining skin is found presiding in many aspects toward strengthening the thermal buckling resistance of the curved sandwich panels. | Thermal Buckling, Vibration and Damping Behavior of Viscoelastic-FGM Sandwich Doubly Curved Panels | 10.1007/s40033-023-00590-8 |
2023-11-24 | Purpose This study focuses on the development of a squeeze film damper (SFD) for reducing the vibration amplitudes of high-speed rotating shafts. The effects of SFD process parameters, including shaft rotation, oil pressure inside the damper, and oil blend percentage, while the rotation of the flexible shaft up to a speed of 10,000 rpm and the vibration amplitudes of the shaft across the x - and z -axes are examined. Methods The experimental design used in this study uses the Box–Behnken design (BBD) method, which is a widely used approach in experimental design. The study also incorporates Response Surface Methodology (RSM) and Analysis of Variance (ANOVA) to optimize the input parameters and assess the statistical significance of the model. Desirability-based optimization is used as a means to attain the intended objectives of vibration control. Results The optimized input parameters, namely the rotational speed of 10,000 revolutions per minute, blend ratio of 13.08%, and oil pressure of 99.82 bar, result in the optimum output values for the x - and z -axis vibration amplitudes, which are measured to be 3.285 µm and 3.268 µm, respectively. Experimental validation is conducted to verify the effectiveness of the optimized values in controlling the vibration of the high-speed rotating shaft. Experimental evaluation of these settings showed changes of 3.125% for the x -axis and 3.91% for the z -axis, confirming the optimization method. Conclusion The measured values closely match the optimized values, with errors well within the acceptable range of less than 5%. The successful experimental validation confirms the accuracy and reliability of the optimized values for vibration control. These findings provide valuable insights for developing and implementing squeeze film dampers (SFD) in rotating shaft applications at high speeds, contributing to improved vibration control and enhanced performance. | Comprehensive Experimental Analysis of a Squeeze Film Damper for Flexible Rotor Applications: Utilizing Box–Behnken Design with Desirability Optimization | 10.1007/s42417-023-01197-9 |
2023-11-24 | This research offers a scientific, industry-driven approach to studying the impact of acceleration and displacement reactions on ride comfort, handling, and safety in automobile suspension design. Different suspension systems were tested at a maximum speed of 240 km/hr, with the Intelligent Control Suspension System (ICSS) and the Passive Suspension System (PSS) standing out. RMS acceleration and displacement data, as well as ride quality and comfort parameters, were used to make the comparisons. Acceleration attenuation studies reveal that the ICSS is superior than the PSS, with reductions ranging from 7.64 to 11.66% across different ICSS configurations. Displacement values improve significantly using ICSS, obtaining reductions ranging from 25.89 to 55.80%. With the application of ICSS, ride quality and comfort indices improve by 8.19 to 31.50%. These findings show that the ICSS is very successful in reducing discomfort caused by rail vibrations and improving passenger comfort. This research emphasizes the significance of acceleration and displacement responses in suspension design and advocates for the use of ICSS for more efficient and pleasant train travel. The adaptable nature of ICSS allows for real-time optimization of suspension settings, which contributes to the development of a sustainable and enjoyable railway sector. | Industry-Driven Approach for ANFIS-Based Intelligent Control Suspension System with MR Damper for Enhanced Ride Quality in Passenger Rail Vehicles for Technological Investigations | 10.1007/s40009-023-01365-1 |
2023-11-22 | Aiming at the situation that some dampers cannot give full play to the energy dissipation effect during small earthquakes, this paper proposes a displacement-amplified mild steel bar joint damper. This type of damper can amplify the small displacement of beam-column nodes through the lever principle, so that the damper can dissipate energy more effectively. Firstly, the amplification principle and construction characteristics are introduced, and ABAQUS finite element software is used to establish damper models with and without displacement amplification. Based on the graphical comparisons of the hysteresis curve and the skeleton curve, it can be concluded that the energy consumption of the proposed displacement-amplified mild steel bar joint is three times more effective than the ordinary damper. Finally, a parameter analysis is carried out with the results shown that (i) the energy dissipation effect of the damper increases with the diameter and the number of mild steel bars in the damper, (ii) the hysteresis curve of the damper is fuller and the energy dissipation effect is better with the use of mild steel energy dissipation original, and (iii) in a certain range, with the increase in the amplification of the damper, the energy dissipation original of the damper is more effective in energy dissipation, so as to make the damper reach the optimal energy dissipation effect. | Study on Mechanical Properties of Displacement-Amplified Mild Steel Bar Joint Damper | 10.1007/s40996-023-01268-7 |
2023-11-17 | Purpose Measurement and analysis of vibration characteristics of plants are of great significance in plant health monitoring, wood material characteristic determination, etc. Currently, vibration characteristics of plants are mainly measured by contact sensors, which need a relatively complex installation procedure, and what's worse, may affect accuracy of test results. Methods In this study, vibration characteristics of Radermachera sinica , including natural frequencies and equivalent damping ratios, are contactlessly measured by a laser Doppler vibrometer (LDV). A mechanical model is developed to simulate the vibration of a plant. By combining this mechanical model with experimental data, the material damping coefficients of the vibrating plant can be determined. Finite-element analysis (FEA) is conducted, and the simulating results are compared with the mechanical model. Results Vibration data of the healthy plant with leaves (Group 1), healthy plant without leaves (Group 2), and diseased plant without leaves (Group 3) are measured and vibration characteristics are obtained by analyzing measurement data of LDV. The experiment results show that the natural frequencies of Radermachera sinica in Group 2 and Group 3 are 1.60 and 2.84 times of that in Group 1, respectively, while the equivalent damping ratios in Group 2 and Group 3 are 0.52 and 1.24 times of that in Group 1, respectively. Furtherly, the material damping coefficient is predicted by the mechanical model, and the result shows that the material damping coefficient in the diseased plant is 1.2 times of that in healthy plants. The results obtained from the FEA align well with the predictions of the mechanical model, thereby confirming the accuracy of the mechanical model. Conclusion The non-contact vibration measurement technique, combined with the mechanical model proposed in this paper, may offer a new approach to identify the health status and determine the material damping of Radermachera sinica and other plants. | Health Status Identification and Material Damping Determination of Plants via Non-contact Measurement and Mechanical Modelling | 10.1007/s42417-023-01193-z |
2023-11-14 | This paper is focused on the Riemann problem for a 2 × 2 $2\times 2$ hyperbolic system of conservation laws with a time-gradually-degenerate damping. Two kinds of non-self-similar solutions involving the delta-shocks and vacuum are obtained using the variable substitution method. The generalized Rankine-Hugoniot relation and entropy condition are clarified for the delta-shock. Furthermore, the vanishing viscosity method proves the existence, uniqueness, and stability of non-self-similar solutions. | Riemann problem for a
2
×
2
$2\times 2$
hyperbolic system with time-gradually-degenerate damping | 10.1186/s13661-023-01798-z |
2023-11-13 | Purpose Squeeze film dampers (SFDs) are used for reducing the vibration amplitude of high-speed rotors. In this context, a SFD has been developed to meet the requirements of high speeds rotating shafts. This study investigates the effect of SFD process parameters (rotation of shaft, oil pressure inside the damper, and oil blend sample) on the vibration amplitude of the shaft on the x-axis and vibration amplitude of shaft in the z-axis during the rotation of the flexible shaft up-to-speed (10,000 rpm). Methods The oil sample used in the present work is mixing 10, 20, 30, 40, and 50% kerosene oil (Dynamic viscosity 1. 1287 mPa.S) in 5W30 crankcase oil (Dynamic viscosity 75.483 mPa.S) with high-pressure oil supply system up to(120bar). The Taguchi approach (L25-orthogonal array) is utilized for experiment design, and the experimental findings are examined using analysis of variance (ANOVA). Results and conclusion The table of Response for an average value of the vibration amplitude of the shaft in the x -axis and z -axis shows that supply oil pressure is the most significant factor for shaft amplitude along the x - and z -axes while blending Newtonian fluid is important for reducing the vibration amplitude. Similar results are also supported by ANOVA. Also, it has been discovered that Pressure—100 bar, Speed—4000 rpm, Blend—40% (P5S2B4) in the x -axis and Pressure 100 bar, Speed—4000 rpm, Blend—50% (P5S2B5) in the z -axis are the optimal levels of process parameters for reducing vibration amplitude. | Development and Experimental Investigations of Squeeze Film Damper Setup for High Rotational Speeds and Oil Pressure | 10.1007/s42417-023-01186-y |
2023-11-11 | We consider a swelling porous-elastic system with single nonlinear damping and nonlinear delay term in the elastic equation. We establish the general decay result using multiplier method. | A general stability result for swelling porous elastic media with nonlinear damping and nonlinear delay term | 10.1007/s13370-023-01126-9 |
2023-11-11 | This investigation focuses on the enhancement of the damping properties of Methyl Methacrylate Acrylonitrile Butadiene Styrene (MABS) through the formulation of a specific blend with a styrene-based elastomer referred to as VDT, and with the incorporation of Ethylene Butylene Styrene grafted Maleic Anhydride (SEBS-g-MAH) as a compatibilizer. In contrast to traditional investigations that primarily focus on the mechanical rigidity, thermal conductivity, and electrical conductivity of materials, this research explores the enhancement of damping properties via the process of melt compounding. Using a twin-screw extruder in a precise melt-mixing process, a multiphase polymer blend is generated by including three different weight ratios (10, 20, and 30 wt.%) of VDT. Furthermore, in order to enhance the compatibility between MABS and VDT, three different weight percentages of SEBS-g-MAH (2, 4, and 6 wt.%) have been used in the blend. Tensile testing, laser confocal microscopy, dynamic mechanical analysis (DMA) and nuclear magnetic resonance (NMR), are used to thoroughly assess the compatibility and effectiveness of the blends. The results indicate that the damping performance of the blend increases in direct proportion to the amount of VDT. Conversely, the addition of SEBS-g-MAH has a non-monotonic effect: the inclusion of 4 wt.% SEBS-g-MAH leads to the most substantial improvements in both damping performance and tensile strength, exceeding the results obtained with 2 wt.% and 6 wt.% compatibilizer. The study highlights the need for carefully choosing the right wt.% of compatibilizers when aiming to formulate polymer blends with enhanced vibration dampening properties. | Enhancing vibration damping properties of MABS/VDT blends using SEBS-g-MAH as a compatibilizer | 10.1007/s10965-023-03819-y |
2023-11-10 | In the present work, we consider a nonlinear Klein–Gordon equation with strong damping, distributed delay and source terms. Under suitable conditions, we prove the blow-up result of solutions. Our result is an extension of many other works in this area. | Global nonexistence of solution for a nonlinear Klein–Gordon equation with strong damping, distributed delay and source terms | 10.1007/s13370-023-01137-6 |
2023-11-07 | In this work we consider a semilinear plate equation with non-constant material density in the context of energy damping models. Existence and uniqueness of regular and generalized solutions are established. The energy associated to this equation is shown to posses a compressed polynomial decay range. | Stability by Polynomial Squeezing for a Class of Energy Damping Plate Models | 10.1007/s10440-023-00619-w |
2023-11-03 | Band gap characteristic of flexural metamaterial beams has been an active area of research for its potential application in providing low-frequency band gaps. The present work brings out investigations on flexural metamaterial beams, highlighting the influence of their design parameters. The metamaterial beams were fabricated by introducing periodic cavities in a thin uniform beam, and filling the cavities by a Viscoelastic Membrane (VEM), and a Resonant Mass (RM). Twelve different metamaterial beams were fabricated for experimental and numerical investigations, by varying the geometrical shape of the cavity or the type of VEM or the mass of RM. Vibration characteristics and band gaps of these metamaterial beams were studied through vibration trials on a vibration shaker. Their vibration characteristics were compared with that of a uniform beam, without any cavity. Two prominent low-frequency band gaps were discernible for the metamaterial beams, which are referred to as ‘local resonance band gaps (LRBGs)’. Dependence of these LRBGs on various design parameters of the metamaterial beam has been presented. Further, the band gap characteristic of a metamaterial beam has been compared to that of a beam with multiple-Tuned Mass Dampers to get further insight into the band gaps of a metamaterial structure. | Influence of cell parameters in local resonator-based metamaterials | 10.1007/s40430-023-04533-y |
2023-11-01 | This paper studies the existence of weak solutions and their asymptotic behaviour to the initial boundary value problem for a multidimensional nonlinear Bresse system. The existence of the solutions of the problem is obtained by appliying Galerkin method. Then, we obtain an explicit decay rate estimation dependent on both the strain-caused stress and the damping terms by using the multiplier method with integral. | Decay rate estimates for a new class of multidimensional nonlinear Bresse systems with time-dependent dissipations | 10.1007/s11587-020-00554-0 |
2023-11-01 | The nonlinear dynamic analysis of rotating composite boring round bar containing carbon nanotubes (CNTs) in boring system is investigated. Firstly, according to both the Halpin–Tsai model and the micro-mechanical theory, the resultant properties of filled-CNT composite material are estimated. Subsequently, the equations in terms of the energies and virtual works for the composite boring bar are derived by taking into the Von Kármán geometric nonlinearity account. Then, the extended Hamilton principle is used to establish the nonlinear dynamic model of the machining system, which includes periodic regenerative chatter cutting force, periodic frictional force, viscoelastic and process damping force. Both methods of Galerkin approximation and multiple time scales for nonlinear equation are utilized to obtain steady-state response of the boring process. The stability of the boring system is explored considering the effects of CNT-related parameters, fiber volume fraction and orientations, stacking sequences, damping coefficient, and cutter geometry features. The results obtained demonstrate that the CNTs inclusion has a considerable effect on the dynamic behavior of the boring process. Furthermore, it is also concluded that the unstable area can be reduced by increasing damping and that the stability of boring process will be enhanced. | Nonlinear chatter of CNTs-reinforced composite boring cutter considering unstable region | 10.1007/s00419-023-02490-5 |
2023-11-01 | Compared with traditional linear models, the nonlinear model of boring can profoundly reveal the physical mechanism and mathematical laws of chatter occurrence, and has more rich scientific connotations. The nonlinear kinematic equations of the composite boring system containing carbon nanomaterials (CNMs) are derived by utilizing the energy method, which is taken to be the entry point for this paper. First of all, the basic mechanical parameters for the composite boring bar CNMs-embedded are derived based on the Halpin–Tsai Model (HTM) and the Rules of Mixture (ROM). From the perspective of continuous distribution, the mathematical expressions of kinetic and potential energy of the rotating boring bar are proposed by introducing the nonlinear strain. The specific and detailed nonlinear dynamic equations of the boring system are obtained using the extended Hamilton’s principle by considering the non-conservative virtual work consists of the nonlinear regenerative cutting and the damping force resulting from the viscoelastic and hysteretic damping of composite. Next, the nonlinear equations above are numerically decomposed and simplified using the general Galerkin method combined with modal expansion. The compact nonlinear equations are solved by the Multi-scale method and the primary and super-harmonic resonance solutions are obtained for the forward and backward modes, respectively. Then, the above nonlinear theoretical models are validated with published literature. Finally, the effects of CNMs, carbon fibers, cutting technological parameters on chatter amplitude as well as the unstable zone (curves) are investigated. The conclusions obtained confirm that the nonlinear theoretical model of the boring system proposed in present paper can effectively predict the complex relationships between various parameters within the boring system and provide theoretical guidance for the design of the composite cutter bar. | Investigation of chatter suppression by using rotating composite boring bar CNT-filled based on a modified nonlinear dynamical model | 10.1007/s11071-023-08986-7 |
2023-11-01 | Due to diminishing system inertia, system operators currently mandate solar photovoltaic (PV) systems to participate in frequency control. In the literature, the standard approach for achieving this has been to combine a PV system with energy storage. However, it has a number of technical and financial drawbacks. With the goal of providing power reserve control (PRC) and allowing PV systems to participate in frequency regulation, this article offers a novel storage-free master-slave-based power control technique for solar photovoltaic (PV) systems. A substantially small-rated master PV operating in maximum power point (MPP) mode estimates the irradiance and temperature online, which are further utilised to evaluate the entire PV curve of the slave PVs. A novel adaptive voltage control mechanism (inner control) is designed for rapid conversion of a power instruction into an appropriate voltage instruction for the linking DC-DC converter. The proposed method merges the MPP and PRC operating regimes into a single integrated regime, enabling a seamless transition between the modes. Additionally, an inertial and damping control scheme is integrated with the proposed PV system, with active power reserves maintained to modulate the PV power reference of the inner controller in response to system requirements. The proposed control strategy is verified on a three-area test system and the Kundurs multi-machine test system in order to quantify the impact on system performance. The findings show that the suggested control method significantly lowers frequency and tie-power variations. | A Master-Slave-Based Power Reserve Control Approach for Solar PV Participation in Frequency Control | 10.1007/s13369-023-08120-0 |
2023-11-01 | This study devises an advanced single-loop output voltage control method for DC/DC converters incorporating a model-free filter, active damping, and nonlinearly designed feedback terms. The resultant output-feedback controller ensures the order reduction property and reduces both the dependence level of the system model and the number of feedback loops. There are two main features that differentiate this from extant results. First, a model-free first-order pole-zero cancellation (PZC) filter extracts the time derivative component from the output voltage measurement according to the first-order dynamics by the order reduction property without any converter model information. Second, an active damping controller forming a modified proportional-integral-derivative structure tracks the output voltage to its desired trajectory along the first-order low-pass filter dynamics by the order reduction property from the PZC, which is independent of the current feedback. Experimental evidence obtained from an actual feedback system adopting a 3-kW prototype DC/DC converter validates the effectiveness of the proposed technique, which demonstrates the capability of the current sensor fault tolerance. | Single-loop order reduction output voltage control with model-free filtering for DC/DC converters | 10.1007/s43236-023-00689-x |
2023-11-01 | In a Hilbert framework, we introduce a new class of second-order dynamical systems that combine viscous and geometric damping but also a time rescaling process for nonsmooth convex minimization. A main feature of these systems is to produce trajectories that lie in the graph of the Fenchel subdifferential of the objective. Moreover, they do not incorporate any regularization or smoothing processes. This new class originates from some combination of a continuous Nesterov-like dynamic and the Minty representation of subdifferentials. These models are investigated through first-order reformulations that amount to dynamics involving three variables: two solution trajectories (including an auxiliary one) and another one associated with subgradients. We prove the weak convergence towards equilibria for the solution trajectories, as well as properties of fast convergence to zero for their velocities. Remarkable convergence rates (possibly of exponential-type) are also established for the function values. We additionally state notable properties of fast convergence to zero for the subgradients trajectory and for its velocity. Some numerical experiments are performed so as to illustrate the efficiency of our approach. The proposed models offer a new and well-adapted framework for discrete counterparts, especially for structured minimization problems. Inertial algorithms with a correction term are then suggested relative to this latter context. | Fast Continuous Dynamics Inside the Graph of Subdifferentials of Nonsmooth Convex Functions | 10.1007/s00245-023-10055-9 |
2023-11-01 | The purpose of this paper is to study the multiplicity of periodic solutions for a class of non-autonomous second-order damped vibration systems. New results are obtained by using Fountain theorem. These results improve the related ones in the literature. | New results on periodic solutions for second order damped vibration systems | 10.1007/s11587-021-00567-3 |
2023-11-01 | In this article, we consider the one-dimensional system of piezoelectric beams with a nonlinear damping term. First, we show the existence and uniqueness of solutions by the semi-group technique more precisely by Hille-Yosida theorem. And by building an appropriate Lyapunov functional, we establish general decay results for the solution of the system whose exponential and polynomial decays are only special cases. Moreover, our results does not depend on any relation between the parameters of the system. | General stability for piezoelectric beams with a nonlinear damping term | 10.1007/s11565-022-00443-4 |
2023-11-01 | Boost derived converters are widely employed due to their simplicity and high reliability when it comes to obtaining a higher voltage level. However, the existence of right half-plane (RHP) zeros in the control-to-output transfer function deteriorates the dynamic performance of this category converters. Integrated coupling between the power inductor and the filter inductor is an effective method to alleviate the influence of RHP zeros. This paper puts forward a novel coupled inductor boost with an RL parallel damping (CIB-RLPD) network, where the input inductor, output inductor, and auxiliary inductor used to achieve RHP elimination have been integrated into a single magnetic core. The operating principle and small-signal analysis of the novel converter in continuous conduction mode (CCM) is discussed in detail. By an optimal design of the parameters of the damping network according to the Routh–Hurwitz Criterion, a novel converter with a good dynamic performance within a wide input voltage range can be achieved, which is a good candidate for renewable applications, particularly for spacecraft power systems. For the sake of comparison, the allowable operation duty ratio range and frequency response of the transfer function for both the original coupled inductor boost (CIB) and the proposed CIB-RLPD are presented in this paper. Finally, prototypes of the CIB and CIB-RLPD are implemented in the laboratory and experimental verifications are given to demonstrate the effectiveness of theoretical predictions. | Novel integrated coupled inductor boost with RL parallel damping network for improving dynamic response | 10.1007/s43236-023-00670-8 |
2023-11-01 | The main goal of this paper is to provide a Reduced Order Model (ROM) able to predict the liquid induced dissipation of the violent and vertical sloshing problem for a wide range of liquid viscosities, surface tensions and tank filling levels. For that purpose, the Delta Smoothed Particle Hydrodynamics ( $$\delta $$ δ -SPH) formulation is used to build a database of simulation cases where the physical parameters of the liquid are varied. For each simulation case, a bouncing ball-based equivalent mechanical model is identified to emulate sloshing dynamics. Then, an interpolating hypersurface-based ROM is defined to establish a mapping between the considered physical parameters of the liquid and the identified ball models. The resulting hypersurface effectively estimates the bouncing ball design parameters while considering various types of liquids, producing results consistent with SPH test simulations. Additionally, it is observed that the estimated bouncing ball model not only matches the liquid induced dissipation but also follows the liquid center of mass and presents the same sloshing force and phase-shift trends when varying the tank filling level. These findings provide compelling evidence that the identified ROM is a practical tool for accurately predicting critical aspects of the vertical sloshing problem while requiring minimal computational resources. | Sloshing reduced-order model trained with Smoothed Particle Hydrodynamics simulations | 10.1007/s11071-023-08940-7 |
2023-11-01 | In this paper, we analyze a speed restarting scheme for the inertial dynamics with Hessian-driven damping, introduced by Attouch et al. (J Differ Equ 261(10):5734–5783, 2016). We establish a linear convergence rate for the function values along the restarted trajectories. Numerical experiments suggest that the Hessian-driven damping and the restarting scheme together improve the performance of the dynamics and corresponding iterative algorithms in practice. | A Speed Restart Scheme for a Dynamics with Hessian-Driven Damping | 10.1007/s10957-023-02290-5 |
2023-11-01 | The goal of this paper is to consider damped elastic systems with nonlocal conditions in the framework of Banach spaces. Our first aim is to investigate the existence of mild solutions to damped elastic systems by means of fixed point for condensing maps avoiding the hypothesis of compactness on the semigroup. The second step of the paper is to study the existence of decay mild solutions to the mentioned problems. The obtained results can be applied to the nonlinear vibration equation of structural damping elastic beams with nonlocal conditions. | A study on decay mild solutions for damped elastic systems in Banach spaces | 10.1007/s00605-023-01883-6 |
2023-11-01 | In this paper we study the well-posedness as well as the stabilization properties of the swelling porous elastic media with structural damping acting on both equations of the system. By using semigroup theory, we prove the system is globally well posed in energy space. We stablished the energy dissipation law since the classical relationship between structural parameters holds and after that we stablished the exponential decay of energy solution by using energy approach. The results are new and the stabilition property holds regardless of any relationship between wave speeds. | A new stability result for swelling porous elastic media with structural damping | 10.1007/s11565-022-00433-6 |
2023-11-01 | Microvibration is a severe issue that is present in many components on spacecraft, such as cryocoolers, thrusters, solar arrays, and momentum/reaction wheel assemblies (M/RWAs), which can severely downgrade the working accuracy of sensitive payloads. To address this dilemma, recently, the development of passive, active or hybrid active–passive and semi-active isolation techniques for microvibration has attracted considerable interest, especially because of the increasing demand in boosting isolation performance for ultraprecision instruments subjected to very small amplitudes. As a useful complement to several existing reviews in the recent literature on microvibration isolation technology, in this paper, several isolation methods considering passive, active, hybrid active–passive and semi-active systems are investigated, exploring both theoretical and experimental results of these techniques. In general, passive approaches are first employed in orbit spacecraft due to their high stability and lack of exogenous energy consumption. Active techniques, however, are usually developed to isolate low-frequency vibrations, which are common in ultraprecision equipment and spacecraft. Hybrid active–passive methods embrace the advantages of both passive and active systems and have also been successfully applied in aerospace engineering for many years. In semi-active techniques, the trade-off between isolation performance and external energy input can adapt well to variations in the spacecraft environment. Additionally, important outcomes of the published work are reviewed. Notably, this paper focuses on a review of state-of-the-art vibration isolation theory and/or techniques that have been developed, mainly over the last decade, and can specifically or potentially be used for microvibration isolation. | Microvibration isolation in sensitive payloads: methodology and design | 10.1007/s11071-023-08943-4 |
2023-11-01 | In this paper, we study the approximate controllability of damped elastic systems with initial conditions without the assumptions that the corresponding linear system is approximately controllable. Firstly, the existence of mild solution is obtained by means of contraction mapping principle and operator semigroup theory. Secondly, using the sequence method, a new set of sufficient conditions for approximate controllability of damped elastic systems are formulated and proved. The results in this paper are generalization and continuation of the recent results on this issue. Finally, as the application of abstract results, an example is given to illustrate our main results. | A Study on the Approximate Controllability of Damped Elastic Systems Using Sequence Method | 10.1007/s12346-023-00895-9 |
2023-11-01 | Vortex-induced vibration is a typical nonlinear fluid–structure interaction phenomenon. Significant challenges to high-precision prediction by the prevalent methods rely on three complex nonlinear dynamic behaviors: nonlinear evolution (NE), vibration peak deviating from the resonance (PD), and nonlinear hysteresis. Although the semi-empirical model is a theoretical and efficient manner, it is difficult to accurately predict the above nonlinear phenomena due to the incomplete mathematical expressions and uncertain parameters. In this paper, a data-knowledge-driven (DKD) augmentation method is proposed to modify the typical wake oscillator model. A comprehensive analysis is first conducted for the effect of the potential aerodynamic damping terms. Motivated by the above analysis, a delay damping term is proposed which contributes to the NE and PD phenomenon by affecting the growth rate of the flow frequency and triggers the mode transition of the coupled system. With these physical understandings, a new model architecture is constructed by combining the delay damping and the Rayleigh damping. Besides, experimental data are utilized to identify the empirical parameters of the model by the ensemble Kalman filter data assimilation technique. The results indicate that the DKD model (marked as Van-Delay-Rayleigh) can accurately compute these nonlinear behaviors for 25 different cylinders. Compared with the original model, the prediction accuracy of the DKD model is improved by 2–5 times. It also shows the generalization capability with various mass-damping parameters, which can reduce the number of wind tunnel tests by 70%. | Data-knowledge-driven semi-empirical model augmentation method for nonlinear vortex-induced vibration | 10.1007/s11071-023-08966-x |
2023-11-01 | The conventional nonlinear control methods for induction motors have the problem of difficult observation of rotor current, and load disturbances make the dynamic performance of the system speed control unsatisfactory. A novel disturbance rejection control scheme with variable damping model based on port controlled Hamiltonian with dissipation is proposed. The induction drive is regarded as energy conversion device including mechanical and electrical ports. The Euler Lagrange equation of the closed-loop system is obtained by the output feedback to establish the energy shaping control method. The variable damping injection is introduced to improve the dynamic performance of the conventional control methods. The $$L_2$$ L 2 disturbance rejection controller is designed to enhance the load disturbance resistance performance of induction motors. The experimental results show that the proposed method can optimize the dynamic and steady-state performance of the induction drive control system and effectively meet the control requirements of the speed and torque under load disturbances. | Disturbance Rejection Control Method Based on Variable Damping and Port Controlled Hamiltonian with Dissipation Model for Induction Drive Motor | 10.1007/s12541-023-00863-y |
2023-11-01 | The oscillating water column (OWC) devices constitute the most widely used systems for the wave energy conversion. Optimizing the performances of such devices mainly composed with a bidirectional air turbine and a water–air chamber still remains of great interest. The present investigations focus on the numerical analysis of an OWC system, the air turbine damping, and on its coupling with the OWC chamber. A validated 2D RANS-VoF numerical model was implemented to determine the optimum induced damping of the OWC device in case of an impulse turbine. The model is based on the concept of the Numerical Wave Tank (NWT). In the present model, the turbine quadratic behavior was simulated with an orifice. Simulations have been conducted in typical cases located on the central zone of the Moroccan Atlantic coast. All the simulated cases are of intermediate water waves which are in compliance with the use of the Stokes’ second-order wave generation. The pneumatic power corresponding to the various values of turbine-induced damping is computed, and the optimum damping accounting for the wave climate variability is identified. It was found that the damping induced by the air turbine is the factor that influence most the OWC chamber efficiency, followed by the climate conditions. | Effects of turbine damping and wave conditions on OWC performances for optimal wave energy conversion | 10.1007/s40722-023-00293-y |
2023-11-01 | This paper treats the problem of a spherical robot with an axisymmetric pendulum drive rolling without slipping on a vibrating plane. The main purpose of the paper is to investigate the stabilization of the upper vertical rotations of the pendulum using feedback (additional control action). For the chosen type of feedback, regions of asymptotic stability of the upper vertical rotations of the pendulum are constructed and possible bifurcations are analyzed. Special attention is also given to the question of the stability of periodic solutions arising as the vertical rotations lose stability. | Stabilization of Steady Rotations of a Spherical Robot on a Vibrating Base Using Feedback | 10.1134/S1560354723060060 |
2023-11-01 | Backgrounds In this paper, a kind of mining MR damper with shear and valve working mode is designed. Compared with the traditional damper, this MR damper has better energy dissipation characteristics and can provide greater damping force in a short time. Its damping can be adjusted with the excitation current. Purposes The aim of the present paper is to analyze and study the performance of this novel mining MR damper and test the working performance and feasibility of this MR damper. Methods Optimizing and establishing a Simulink dynamic simulation model based on Bingham model and testing the performance parameters of the MR damper. The vibration mitigation experiment of mining vibrating screen based on spring damper is designed. Results This paper compares the experimental and simulation results and found that the error of the maximum damping force shall not exceed 3%.Compared with traditional metal spring and ROSTA spring, the MR damper can reduce the downtime of the vibrating screen by more than 80%. Conclusions From the results, the present paper provides theoretical basis for the performance test of the damper. The excitation current is the main factor affecting the maximum damping force of the MR damper. The correlation between the excitation current and the maximum damping force is more than 90%. MR damper can not only effectively avoid the resonance of the vibrating screen, but also will not affect the stable amplitude of the vibrating screen when it works, and can also greatly reduce the downtime of the vibrating screen. | Research on the Performance of a Novel Magnetorheological Damper for Mining | 10.1007/s42417-022-00794-4 |
2023-11-01 | Regular and singular dust ion-acoustic solitons structures have been investigated employing a semi-analytical scheme, Adomian decomposition method (ADM). The Damped Korteg-de Vries (DKdV) equation has been derived using the reductive perturbation technique from the set of governing equations of the unmagnetized collisional dusty plasmas comprising ions, dust grains, and superthermal electrons. We have constructed an approximate analytical scheme with the help of ADM to obtain regular as well as singular soliton structures. The prime scope of this work is to analyze singular solitons structures which have not been obtained from the usual techniques that are available for evaluating regular soliton solutions with damping. The results indicate that the singular solitons behavior of DKdV increases for increasing values of Mach number and decreases for spectral index parameter. Further, the soliton solution of DKdV shows similar compressive and rarefactive behavior as that of solitons. The DKdV soliton results obtained from the ADM have been compared to the existing results and are found to be in good agreement. Hence the proposed work would be a way to demonstrate the potential and effectiveness of ADM for various kinds of nonlinear equations arising in the soliton theory. | Regular and singular dust ion-acoustic soliton structures in superthermal plasmas: Adomian decomposition approach | 10.1007/s12648-023-02703-1 |
2023-11-01 | Sugar beet ( Beta vulgaris L.) is an economically important crop in temperate climates providing nearly 30% of sugar production worldwide. The oomycete Aphanomyces cochlioides is the causative agent of seedling damping-off and root rot disease in sugar beet. The pathogen is responsible for plant degeneration and drastic yield losses in all major sugar beet producing areas. The identification of resistant germplasm is essential to reduce the use of chemical treatments as well as the costs of protective measures and to effectively limit the damage caused by the pathogen. In this study we aimed to establish a qPCR-based method to quantify the pathogen DNA in infected plants and to predict the resistance levels of different sugar beet genotypes in response to A. cochlioides . The difference in the response to A. cochlioides isolates with different geographical origins was investigated. In addition, confocal microscopy was performed in order to observe the spatial and temporal colonization pattern in infected seedlings of susceptible and partially resistant breeding lines. The research presented in this article provides a tool to understand the progress of the infection in infected tissues and to identify the genetic background of resistance to A. cochlioides that can be used to support breeding programs. | Rapid detection and quantification of Aphanomyces cochlioides in sugar beet | 10.1007/s42161-023-01490-2 |
2023-11-01 | The effective damping characteristics of a polymer-based unidirectional fiber-reinforced composite are explored. A continuum micromechanical formulation is used to determine the effective damping parameters of a fiber-reinforced composite by the strain energy method. The damping properties include the loss factors corresponding to extensional, shear and coupled shear-extensional strains of the composite. First, the effective parameters of a homogenized composite are expressed employing phase-volume-averaged strain concentration matrices. These matrices are numerically evaluated by applying homogeneous displacement boundary conditions to the finite element formulation of the representative volume element (RVE) of composite. The accuracy of the present micromechanics formulation of RVE is established by comparing the loss factors calculated using the present model with those available in the published literature. The results obtained are also compared with existing experimental data. The damping properties calculated by the present model agree well with their experimental values. The effect of various cross-sectional shapes of fibers in the composite on the normal and shear loss factors calculated is also investigated. | A Numerical Model for the Effective Damping Properties of Unidirectional Fiber-Reinforced Composites | 10.1007/s11029-023-10150-6 |
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