Input: Comprehensive mechanical tests are carried out on two new PolyJet elastomers.

mechanical tests

PolyJet

elastomers


Input: The stress-strain response of PolyJet elastomers is highly sensitive to strain rate.

PolyJet

strain rate

elastomers


Input: A visco-hyperelastic material model captures the strain rate sensitivity of the elastomers.

material

elastomers

strain rate sensitivity


Input: The elastomers fully recover after 20 s after repeated cyclic loading.

elastomers

s

cyclic loading


Input: Anisotropy in the elastomers is dependent on strain and strain rate.

Anisotropy

strain

elastomers

strain rate


Input: Material jetting, particularly PolyJet technology, is an additive manufacturing (AM) process which has introduced novel flexible elastomers used in bio-inspired soft robots, compliant structures and dampers.

Material jetting

additive manufacturing

AM

PolyJet

process

bio-inspired

elastomers

robots


Input: Finite Element Analysis (FEA) is a key tool for the development of such applications, which requires comprehensive material characterisation utilising advanced material models.

Finite Element Analysis

tool

material

material


Input: However, in contrast to conventional rubbers, PolyJet elastomers have been less explored leading to a few material models with various limitations in fidelity.

rubbers

elastomers

material

PolyJet


Input: Therefore, one aim of this study was to characterise the mechanical response of the latest PolyJet elastomers, Agilus30 (A30) and Tango+ (T+), under large strain tension-compression and time-dependent high-frequency/relaxation loadings.

mechanical response

PolyJet

elastomers

strain


Input: Another aim was to calibrate a visco-hyperelastic material model to accurately predict these responses.

material

accurately


Input: Tensile, compressive, cyclic, dynamic mechanical analysis (DMA) and stress relaxation tests were carried out on pristine A30 and T+ samples.

Tensile

dynamic mechanical analysis

DMA

stress relaxation

samples


Input: Quasi-static tension-compression tests were used to calibrate a 3-term Ogden hyperelastic model.

Quasi-static

model


Input: Stress relaxation and DMA results were combined to determine the constants of a 5-term Prony series across a large window of relaxation time (10 μs–100 s).

Stress relaxation

DMA

s


Input: A numerical time-stepping scheme was employed to predict the visco-hyperelastic response of the 3D-printed elastomers at large strains and different strain rates.

strain rates


Input: In addition, the anisotropy in the elastomers, which stemmed from build orientation, was explored.

anisotropy

elastomers

build orientation


Input: Highly nonlinear stress-strain relationships were observed in both elastomers, with a strong dependency on strain rate.

elastomers

strain rate


Input: Relaxation tests revealed that A30 and T+ elastomers relax to 50% and 70% of their peak stress values respectively in less than 20 s. The effect of orientation on the loading response was most pronounced with prints along the Z-direction, particularly at large strains and lower strain rates.

elastomers

stress

orientation

strain rates

Z-direction


Input: Moreover, the visco-hyperelastic material model accurately predicted the large strain and time-dependent behaviour of both elastomers.

material

elastomers

accurately

strain


Input: Our findings will allow for the development of more accurate computational models of 3D-printed elastomers, which can be utilised for computer-aided design in novel applications requiring flexible or rate-sensitive AM materials.

accurate

be

AM materials

computer-aided design


Input: Measures thermal conductivity of additively manufactured components.

thermal conductivity

additively manufactured


Input: Demonstrates significant direction-dependence of thermal conductivity.

thermal conductivity


Input: Demonstrates significant effect of process parameters.

process parameters


Input: Results may be helpful in design of 3D-printed heat transfer components.

be

design

components


Input: Additive manufacturing, or 3D printing, is an exciting manufacturing technique based on layer-by-layer build-up as opposed to the subtractive approach in most traditional machining processes.

Additive manufacturing

3D printing

manufacturing

subtractive

machining

layer-by-layer

as


Input: Specifically, in polymer-based additive manufacturing processes, filaments of a polymer are dispensed from a rastering extruder to define each layer.

additive manufacturing processes

filaments

polymer

extruder

layer


Input: Due to the directional nature of this process, it is of interest to determine whether thermal transport properties of the built part are direction dependent.

process

properties

transport


Input: Such an understanding is critical for accurate design of components that serve a thermal function.

accurate

components


Input: This paper reports measurement of thermal conductivity of additively manufactured polymer samples in the filament rastering direction and in the build direction.

measurement

thermal conductivity

additively manufactured

samples

filament

build direction


Input: Samples are designed and built in order to force heat flow only in one direction during thermal property measurement.

Samples

force

thermal property

designed

measurement


Input: Experimental data indicate significant anisotropy in thermal conductivity, with the value in the build direction being much lower than in the raster direction.

Experimental data

anisotropy

thermal conductivity

build direction


Input: Both thermal conductivities are found to depend strongly on the air gap between adjacent filaments.

thermal conductivities

filaments


Input: A theoretical thermal conduction model is found to be in good agreement with experimental data.

theoretical

model

experimental data

be


Input: Cross section images of samples confirm the strong effect of the gap on the microstructure, and hence on thermal properties.

Cross section

samples

microstructure

thermal properties


Input: Results from this paper provide a key insight into the anisotropic nature of thermal conduction in additively manufactured components, and establish the presence of significant inter-layer thermal contact resistance.

anisotropic

additively manufactured

contact


Input: These results may be helpful in the fundamental understanding of heat transfer in 3D-printed components, as well as in accurate design and fabrication of heat transfer components through 3D printing.

be

as

as

heat transfer

heat transfer

fabrication

3D printing

accurate

components


Input: A computational fluid dynamics model is used to predict the mesostructure formed by the successive deposition of parallel strands in material extrusion additive manufacturing.

computational fluid dynamics

deposition

material extrusion additive manufacturing


Input: The numerical model simulates the extrusion of the material onto the substrate.

model

extrusion

material

substrate


Input: The simulated mesostructures are compared to optical micrographs of the mesostructures of 3D-printed samples, and the predictions agree well with the experiments.

optical

predictions


Input: In addition, the influence of the layer thickness, the strand-to-strand distance, and the deposition configuration (with aligned or skewed layers) on the formation of the mesostructure is investigated.

layer thickness

deposition configuration


Input: The simulations provide detailed information about the porosity, the inter- and intra-layer bond line densities, and the surface roughness of the mesostructures, which potentially can be used in a model-based slicing software.

simulations

porosity

surface roughness

be

slicing


Input: Lithography-based Additive Manufacturing Technologies (L-AMT) exploit the curing of photosensitive materials upon light exposure.

Additive Manufacturing

curing

materials

light exposure


Input: We developed a hybrid exposure concept.

exposure


Input: This system is able to overcome the challenge of providing good surface qualities and excellent feature resolution as well as a throughput similar to dynamic mask-based L-AMT systems by combining two light sources.

surface qualities

feature

as

as

throughput

dynamic

light sources


Input: A Digital Light Processing (DLP®) Light Engine (LE) with a building area of 144 x 90 mm² offers a pixelsize of 56 μm.

Digital Light Processing

area


Input: In order to further improve the achievable resolution, a continuous laser-exposed contour line (spot size 20 μm) on the outside of the projected envelope can be written with an additional scanning laser-system.

resolution

spot size

contour

be

scanning


Input: The matching of the DLP® projection mask and the laser-contour is crucial for accurate printing.

mask

accurate


Input: Therefore a calibration tool was developed, which facilitates the alignment of the two light sources.

calibration

light sources


Input: A dichroic coated mirror enables a perpendicular alignment of the DLP® light beam and the laser beam.

coated

beam

laser beam


Input: In this paper, we formulate the generation of support structures for additive manufacturing as a topology optimization problem.

support structures

topology optimization

additive manufacturing


Input: Compared with usual geometric considerations based support structure design, this formulation affords mechanistic meaning to the computed support structures.

support structure

design

support structures


Input: Moreover, our study reveals that the topology optimization formulation generally leads to self-supporting designs without extraneous self-supporting constraints.

topology optimization

self-supporting designs

self-supporting


Input: The resulting support structures have been 3D printed, demonstrating that the computed designs can successfully be used as supports.

support structures

designs

3D printed

be

as


Input: To better understand the impact of complex structure on mechanical properties in additively manufactured ceramics, truss structures were 3D printed in preceramic polymer and mechanically evaluated in the pyrolyzed SiOC state.

impact

complex structure

mechanical properties

additively manufactured

3D printed

truss

polymer


Input: Specimens were printed using digital light processing with a siloxane polymer resin blend.

digital light processing

polymer resin

blend


Input: Four different designs were printed: two bending-dominant Kelvin cell structures, a stretching-dominant octet structure, and a mixture of the two with geometries chosen for equivalent stiffness.

designs

cell

octet structure

geometries

stiffness


Input: Mechanical characterization was done at multiple length scales: uniaxial compression to evaluate the entire truss structure, and three-point flexure to assess individual beam elements.

Mechanical

length scales

compression

truss

flexure

beam

structure


Input: After pyrolysis, it was found that truss designs exhibited different shrinkages at the beam element scale despite being composed of the same preceramic polymer and exhibiting isotropic shrinkage at the macro-truss scale.

pyrolysis

truss

beam

designs

polymer

isotropic


Input: This manner of nonuniform shrinkage has rarely, if ever been reported, as it is standard practice in additive manufacturing to report only bulk linear shrinkage.

shrinkage

standard

shrinkage

as

additive manufacturing


Input: In uniaxial compression, Kelvin structures with thicker beams exhibited the highest strength of 10 MPa, and octet structures exhibited the lowest strength of 3.8 MPa.

compression

strength

strength

MPa

octet structures

MPa


Input: In beam element flexure however, the octet beams had the highest strength, 1.9 GPa, four times stronger than the Kelvin beam elements and 500 times stronger than the octet bulk structure.

beam

flexure

beam

strength

GPa

structure


Input: Achieving better control in fused filament fabrication (FFF) relies on a molecular understanding of how thermoplastic printing materials behave during the printing process.

fused filament fabrication

FFF

printing process

thermoplastic

materials


Input: For semi-crystalline polymers, the ultimate crystal morphology and how it develops during cooling is crucial to determining part properties.

polymers

morphology

properties

cooling


Input: Here crystallisation kinetics are added to a previously-developed model, which contains a molecularly-aware constitutive equation to describe polymer stretch and orientation during typical non-isothermal FFF flow, and conditions under which flow-enhanced nucleation occurs due to residual stretch are revealed.

model

orientation

nucleation

residual

polymer

FFF


Input: Flow-enhanced nucleation leads to accelerated crystallisation times at the surface of a deposited filament, whilst the bulk of the filament is governed by slower quiescent kinetics.

nucleation

surface

filament

filament


Input: The predicted time to 10% crystallinity, t10, is in quantitative agreement with in-situ Raman spectroscopy measurements of polycaprolactone (PCL).

predicted

quantitative

in-situ

spectroscopy

PCL


Input: The model highlights important features not captured by a single measurement of t10.

model

measurement


Input: In particular, the crystal morphology varies cross-sectionally, with smaller spherulites forming in an outer skin layer, explaining features observed in full transient crystallisation measurements.

morphology

transient

forming

layer


Input: Finally, exploitation of flow-enhanced crystallisation is proposed as a mechanism to increase weld strength at the interface between deposited filaments.

as

filaments

mechanism

interface

weld strength


Input: In nature, mesoscopic or microscopic cellular structures like trabecular bone, wood, shell, and sea urchin, can have high load-carrying capacity.

cellular structures

trabecular bone

wood

shell

capacity


Input: These cellular structures with diverse shapes, forms and designs can be mainly classified into open and closed cell cellular structures.

cellular structures

designs

be

cell


Input: It is difficult to replicate these natural complex lattice structures with traditional manufacturing, but additive manufacturing (AM) technology development has allowed engineers and scientists to mimic these natural structures.

lattice structures

traditional manufacturing

additive manufacturing

AM

technology

mimic


Input: Fabricating close cell lattice structures is still considered difficult due to the support structure within the lattices.

Fabricating

cell

support structure

lattices


Input: This paper evaluates a novel way of fabricating a close cell lattice structure with a material extrusion process.

fabricating

material extrusion

cell

structure


Input: The design eliminates the need for support structures and the subsequent post-processing required to remove them.

design

support structures

post-processing


Input: A shell-shaped close cell lattice structure bio-mimicking a sea urchin shape was introduced for the load-bearing structure application.

cell

structure

load-bearing


Input: The mechanical properties of the proposed structure, including stiffness, deformation behavior and energy absorption, were compared with those of benchmarked honeycomb and open cell sea urchin (SU) lattice structures of the same density.

mechanical properties

structure

deformation

honeycomb

stiffness

density

energy absorption

cell

lattice structures


Input: SU lattice structures and honeycomb periodic lattice structures with varied sizes but the same morphology and fixed density were designed and printed in polylactic acid material (PLA).

lattice structures

lattice structures

designed

honeycomb

morphology

density

polylactic acid material

PLA


Input: Their physical characteristics, deformation behavior, and compressive properties were investigated experimentally and via finite element analysis.

deformation

properties

finite element analysis


Input: The effect of the unit cell size on mechanical properties was studied and discussed, and the rankings of better performances were drawn.

unit cell

mechanical properties


Input: A possible application of the closed cell is for fabricating the load bearing structure; it can also be encapsulated within a fluid to impart strength and damping characteristics.

cell

fabricating

structure

be

fluid

strength


Input: An anisotropic cohesive zone model with XFEM is developed to capture fracture in additively manufactured polymer materials.

anisotropic

model

fracture

materials

additively manufactured


Input: The XFEM is able to model crack propagations in 3D printed materials without knowing a priori the crack path.

model

crack propagations

3D printed


Input: Parametric studies show that the competition between inter-layer failure and max principal stress failure largely affects the kinked cracks.

failure

failure

principal stress


Input: The fracture of additively manufactured polymer materials with various layer orientations is studied using the extended finite element method (XFEM) in an anisotropic cohesive zone model (CZM).

fracture

materials

finite element method

model

additively manufactured

layer

anisotropic


Input: The single edge notched bending (SENB) specimens made of acrylonitrile-butadiene-styrene (ABS) materials through fused filament fabrications with various crack tip/layer orientations are considered.

bending

fused filament fabrications

ABS

materials

orientations


Input: The XFEM coupled with anisotropic CZM is employed to model the brittle fracture (fracture between layers), ductile fracture (fracture through layers), as well as kinked fracture behaviors of ABS specimens printed with vertical, horizontal, and oblique layer orientations, respectively.

anisotropic

model

brittle fracture

fracture

ductile fracture

fracture

fracture

vertical

as

as

ABS

layer


Input: Both elastic and elastoplastic fracture models, coupled with linear or exponential traction-separation laws, are developed for the inter-layer and cross-layer fracture, respectively.

elastic

fracture

fracture


Input: For mixed inter-/cross- layer fracture, an anisotropic cohesive zone model is developed to predict the kinked crack propagations.

layer

fracture

model

crack propagations

anisotropic


Input: Two crack initiation and evolution criteria are defined to include both crack propagation between layers (weak plane failure) and crack penetration through layers (maximum principal stress failure) that jointly determine the zig-zag crack growth paths.

evolution

crack propagation

failure

penetration

maximum principal stress failure

crack growth


Input: The anisotropic cohesive zone model with XFEM developed in this study is able to capture different fracture behaviors of additively manufactured ABS samples with different layer orientations.

anisotropic

model

fracture

additively manufactured

ABS

layer


Input: A conformal, compliant and multi-layer tactile sensor was built layer by layer using a hybrid manufacturing process including conformal Direct-Print (DP) technology and layer by layer soft molding process with a developed piezoresistive polymer/nanocomposite.

sensor

layer by layer

hybrid manufacturing

technology

layer by layer

molding


Input: A multi-layer conformal skin structure of the sensor was created using the soft molding process along with a highly flexible rubber material.

structure

sensor

molding

rubber material


Input: Two layers of sensing elements were designed, where the sensing elements in the lower sensing layer were orthogonally placed against those in the upper sensing layer so that the sensing elements in two layers could cross each other with an insulating layer between them.

sensing

sensing

sensing

sensing

sensing

elements

elements

elements

designed

layer

layer

insulating layer


Input: A conformal printing algorithm was developed to advance the capability of DP technology.

algorithm

technology


Input: Thus, all the sensing elements were printed uniformly within the conformal skin structure.

sensing

elements

structure


Input: Several experiments on position detection were performed to evaluate the performance of the fabricated conformal sensor.

performance

fabricated

sensor


Input: The results showed that the sensor can detect locations of external forces applied on the sensor surface due to the multiple layers of sensing elements.

sensor

sensor

forces

sensing

elements


Input: It is concluded that the suggested manufacturing methods and developed materials are promising tools to develop conformal, compliant tactile sensors.

manufacturing

materials

tools

sensors


Input: Microstereolithography (MSL) has been employed to create 3D microstructures for a wide range of applications.

Microstereolithography

range


Input: Despite the many advantages of using this process, there are still several drawbacks such as the need to use a large amount of a material compared to the volume of the microstructure to be built, oxygen inhibition, and difficulty in processing highly viscous photopolymers.

process

volume

microstructure

as

material

be

oxygen

photopolymers


Input: To minimize the amount of material required, the use of a liquid bridge has been suggested as a modification to the existing microstereolithography process.

material

as

bridge

microstereolithography


Input: A liquid bridge can be easily found in nature after a rainfall.

bridge

be


Input: Basically, a bridge can be formed between two solid bodies, where surface tension can sustain a liquid bridge against a gravitational force, which tends to destroy it.

bridge

bridge

be

surface tension

force


Input: With this natural phenomenon, a photopolymer can be intentionally formed between two substrates: a transparent substrate with a low surface energy can be used as a top substrate, while another substrate with a higher surface energy can be used to hold the fabricated structure together.

photopolymer

be

substrate

be

as

substrate

substrate

be

transparent

surface

surface

fabricated


Input: This process, called liquid bridge microstereolithography (LBMSL), is advantageous since it uses a relatively small amount of a material, removes oxygen inhibition due to the constraint of the material surface, and offers the possibility of utilizing a highly viscous material.

process

bridge

material

oxygen

material

material


Input: In this study, a mathematical model was taken to simulate a liquid bridge with a certain volume and height.

mathematical

volume

bridge


Input: Adhesion tests were accomplished to ensure the fabricated layer detaches from the top substrate while the fabricated structure remains attached to the bottom structure.

Adhesion

fabricated

fabricated

structure

substrate


Input: Finally, various 3D microstructures were fabricated by LBMSL; these fabricated microstructures provide compelling evidence that LBMSL is advantageous over the existing process for MSL.

fabricated

fabricated

process


Input: The paper presents a method to optimize build orientation and topological layout simultaneously in density-based topology optimization for additive manufacturing.

build orientation

layout

topology optimization

additive manufacturing


Input: Support structures are required in additive manufacturing of parts of complex shape.

Support structures

additive manufacturing

complex shape


Input: To eliminate or reduce support structures during the additive processes, we constrain the lower bound of the overhang angle of the optimized design.

support structures

design

additive

overhang angle


Input: In this method, the build orientation and the density field used to represent the part are simultaneously optimized to satisfy the overhang angle constraints for part self-support.

build orientation

overhang angle

density field


Input: The first directional gradient based global constraint controls the overhang angle of the solid/void interface inside the design domain to eliminate the internal supports.

overhang angle

interface

design

supports


Input: The second density-based global constraint controls the angle of the design domain boundary to reduce the external supports.

design

boundary

supports


Input: Numerical examples on both 2D and 3D linear elastic problems are presented to demonstrate the validity and efficiency of the proposed formulations in the build orientation optimization and in the overhang angle control.

elastic

build orientation

overhang angle


Input: As the application space for large-scale 3D printed components continues to grow, it is necessary to identify appropriate processing conditions for high-performance thermoplastics on large format Additive Manufacturing (LFAM) systems.

As

thermoplastics

3D printed

Additive Manufacturing


Input: This study compares the rheological behavior of a high-performance thermoplastic, polyphenylsulfone (PPSU), with that of a commonly used low-temperature polymer, acrylonitrile butadiene styrene (ABS), to identify suitable processing conditions for large format AM systems.

rheological

thermoplastic

polymer

acrylonitrile butadiene styrene

ABS

AM


Input: The linear viscoelastic properties (complex viscosity, storage modulus, loss modulus, and tan delta) of these materials are evaluated as a function of temperature, angular frequency, and carbon fiber content.

viscoelastic properties

viscosity

materials

as

carbon fiber

temperature


Input: The addition of 20–35% by weight of carbon fiber increased the shear thinning effect of both thermoplastics, showing a potential variation of 2–3 x over the range of expected LFAM extrusion shear rates (10–100 s−1).

weight

range

carbon fiber

thermoplastics

shear thinning

variation

extrusion


Input: Sustainable and environmentally friendly process for spherical poly (L-lactide) (PLLA) particles for Additive Manufacturing.

Sustainable

process

spherical

particles

Additive Manufacturing


Input: PLLA microspheres produced by liquid-liquid phase separation and precipitation using triacetin as solvent.

microspheres

phase

precipitation

as


Input: Particle characterization with respect to processability in powder bed fusion (PBF) of polymers.

Particle

powder bed fusion

PBF

polymers


Input: Narrowly distributed, spherical PLLA powders show excellent flowability.

spherical

powders


Input: Manufacturing and mechanical characterization of 3D printed tensile test bars and complex porous gyroid specimens.

Manufacturing

3D printed

mechanical

porous


Input: In this work, the development and processing behavior of poly (L-lactide) (PLLA) particles for powder bed fusion (PBF) of polymers obtained via a green and sustainable process route are thoroughly studied.

particles

sustainable process

powder bed fusion

PBF

polymers


Input: Liquid-liquid phase separation and precipitation from triacetin, a non-toxic solvent, are applied for the production of highly spherical PLLA particles of excellent flowability.

phase

precipitation

spherical

particles

production


Input: Starting from the measured cloud-point diagram of the PLLA-triacetin system, appropriate temperature profiles for the precipitation process are derived.

temperature

profiles

precipitation


Input: The effect of process parameters on the product properties is addressed in detail; the PLLA particles are characterized regarding their size distribution and morphology.

process parameters

properties

particles

distribution

morphology


Input: Furthermore, material properties including thermal behavior (c.f.

material properties


Input: processing window for powder bed fusion (PBF)) and powder flowability are assessed.

powder bed fusion

PBF

powder


Input: The spherical PLLA particles of narrow size distribution display a wide sintering window of 59 K and an excellent flowability due to the intrinsic surface roughness of the particles.

spherical

particles

distribution

particles

sintering

K

surface roughness


Input: Thus, tensile test bars and complex porous gyroid specimens were successfully manufactured via PBF without the need for any additional surface functionalization of the particles with flow agents.

tensile test

porous

manufactured

surface

particles

PBF


Input: The high potential of the newly developed PLLA powders produced via an environmentally friendly approach omitting the use of halogenated or toxic solvents, as well as flowing aids, is demonstrated by mechanical testing of the printed specimens.

powders

as

as

mechanical testing


Input: Composite textiles have found widespread use and advantages in various industries and applications.

Composite

industries


Input: The constant demand for high-quality products and services requires companies to minimize their manufacturing costs and delivery time in order to compete with general and niche marketplaces.

companies

manufacturing costs


Input: Creation of molding and tooling options for advanced composites encompasses a large portion of fabrication time, making it a costly process and a restraining factor.

molding

tooling

process

advanced composites

fabrication time


Input: This research discusses a preliminary investigation into the use and control of soluble polymer compounds and additive manufacturing to fabricate sacrificial molds.

research

soluble

polymer

additive manufacturing

fabricate

molds


Input: These molds suffer from dimensional errors due to several factors, which have also been characterized.

molds

errors


Input: The basic soluble mold of a composite is 3D printed to meet the desired dimensions and geometry of holistic structures or spliced components.

soluble

geometry

mold

components

composite

3D printed

dimensions


Input: The time taken to dissolve the mold depends on the rate of agitation of the solvent.

mold

agitation


Input: This process is steered towards enabling the implantation of optoelectronic devices within the composite to provide a sensing capability for structural health monitoring.

process

implantation

composite

sensing


Input: The shape deviation of the 3D printed mold is also studied and compared to its original dimensions to optimize the dimensional quality to produce dimensionally accurate parts of up to 0.02% error.

3D printed

dimensions

quality

error

accurate


Input: In order to use selective laser sintering to manufacture structural parts for automotive and aerospace applications, the failure conditions of such a component must be understood and predicted.

selective laser sintering

manufacture

failure

predicted

automotive

aerospace

component

be


Input: A 3D failure criterion for anisotropic materials that incorporates stress interactions is implemented to predict failure of selective laser sintered parts manufactured using polyamide 12 powder.

failure

manufactured

anisotropic

stress

selective laser

polyamide 12


Input: Special test specimens that capture tensile, compressive and shear strengths, as single or combined loads, were designed, manufactured and tested.

tensile

shear strengths

as

designed

manufactured


Input: Results show that significant differences exist between tensile and compressive strengths, and that failure of additive manufactured parts is strongly influenced by the interaction between stresses.

tensile

compressive strengths

failure

additive manufactured parts


Input: The test data shows an excellent fit with a tensor based failure criterion that includes interaction strength tensor components, thus being able to capture the strength behavior of SLS printed components under complex loading conditions.

data

fit

tensor

failure

strength

strength

components

components

SLS


Input: Vat photopolymerization (VP) of silicone can produce better finish and higher resolution than the conventional extrusion-based method.

Vat photopolymerization

silicone

higher resolution


Input: One challenge in the current bottom-up VP processes is the separation that forms between the cured part and vat at each layer.

processes

cured

vat

layer


Input: Oxygen-inhibition is commonly adopted as a solution (i.e.

as

solution


Input: LOPP is achieved by a low-absorbance wavelength and a gradient light beam.

wavelength

beam


Input: The first experiment measured the effect of beam power; the second experiment measured the effect of scanning speed.

experiment

experiment

beam

scanning speed


Input: The curing speed of 385 nm at the same power level was 10 times slower than 375 nm, but could be scaled up non-linearly by the beam power.

curing

power

be

beam


Input: A tripled light power of 385 nm can accelerate the process by a factor of 7 and be comparable to that of 375 nm.

power

process

be


Input: Thus, this study confirms the feasibility of an optically created dead zone and also uncovers the necessity of high-power light source for this application.

feasibility

light source


Input: Fused deposition modelling (FDM) is a well-known additive manufacturing technique, which can transfer digital three-dimensional (3D) models into functional components directly.

Fused deposition

three-dimensional

functional components

FDM

additive manufacturing


Input: Despite many advantages FDM can offer, poor surface accuracy of fabricated objects has always been a big issue that attracts increasing attention.

FDM

surface accuracy

fabricated


Input: To study the influence on the surface profiles imposed by various process parameters effectively as well as quantitatively, the mathematical model of the surface profile need to be developed.

surface profiles

surface profile

process parameters

mathematical

as

as

be


Input: In this work, a new surface profile model is developed to characterize the surface profile of FDM fabricated parts.

surface profile

surface profile

model

fabricated

FDM


Input: The process parameters are classified into two groups (i.e.

process parameters


Input: pre-process parameters and fabrication process parameters) to investigate the impacts on surface characterization.

parameters

parameters

fabrication

surface characterization


Input: Corresponding experiments are conducted using an FDM machine to make comparison with the predicted values and to validate the reliability and effectiveness of the proposed surface models.

FDM

predicted

effectiveness

reliability

surface models


Input: Both the experimental results and theoretical values indicate that the surface accuracy of the top surface is mainly determined by the ratio between molten paste flowrate and the nozzle feedrate under specified layer thickness and path spacing.

experimental

theoretical

surface

surface accuracy

nozzle

layer thickness


Input: On the other hand, the surface quality of the side surface is primarily affected by the layer thickness and the stratification angle of the surface.

surface quality

layer thickness

surface

surface


Input: At the same time, some optimization approaches for the surface improvement are presented: appropriate ratio between paste flowrate and fabrication speed are required for desirable top surface and thinner layer thickness can, to some extent, alleviate the staircase effect out of the slicing procedure and the stratification angle of the side surface should be confined to a range to avoid large geometric errors.

optimization

surface

surface

slicing

surface

errors

fabrication

layer thickness

range

be


Input: In this study, an in situ bioprinting-based methodological workflow is advanced to directly fabricate a custom engineered skin graft onto a skin burn phantom.

in situ

workflow

fabricate


Input: To illustrate this modular approach, a burn phantom is first created by mold casting gelatin-alginate hydrogel material to simulate a burn wound bed with arbitrary 2D shape and uniform depth.

modular

mold

bed

casting

hydrogel


Input: The cast hydrogel phantom is then placed on the printer platform to host the to-be-printed skin graft.

cast

printer platform


Input: This is followed by implementing a contour calibration process based on fiducial markers to yield the real dimension and pose of the burn phantom.

contour calibration

dimension


Input: A new directed toolpath generation algorithm is detailed to generate a burn-specific toolpath for the microextrusion-based bioprinting process.

toolpath

toolpath

algorithm

bioprinting


Input: Based on this method, the bioprinted cell-laden gelatin-alginate hydrogel filaments are precisely arranged in a meshed pattern that is bound by the burn phantom contour.

hydrogel filaments

pattern

contour


Input: Internal geometries defined by the filament and pore dimensional characteristics of the printed construct design can be controlled to promote cell viability, proliferation, and nutrient delivery.

Internal geometries

design

filament

be

pore

printed construct

cell viability


Input: Printed cell-laden multi-layered constructs are evaluated for single filament and pore dimensional precision, alignment of filaments between layers, and positional accuracy of the filaments within the extracted contour.

filament

filaments

filaments

pore

precision

accuracy

extracted contour


Input: Finally, a 24-hour time course incubation study reveals that the printed constructs preserve their structural properties while cells proliferate and maintain their spatial positioning.

printed constructs

properties

cells


Input: X-ray interferometry provides a dark-field image, essentially a small-angle X-ray scattering image, of the voids and print defects in an additively manufactured polymer object.

X-ray

X-ray

interferometry

image

image

voids

defects

print

additively manufactured


Input: The samples studied included Stanford Bunnies, fabricated from acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA), and a quadratic test object fabricated from PLA.

samples

fabricated

fabricated

acrylonitrile butadiene styrene

ABS

polylactic acid

PLA

PLA


Input: The dark-field projection images show orientation-dependent X-ray scattering which is due to anisotropic voids and gaps at the filament-to-filament interface in these fused deposition modeling additive manufacturing objects.

images

interface

X-ray

anisotropic

fused deposition modeling

additive manufacturing


Input: SEM corroborates the existence of gaps between filaments.The absorption and dark-field volumes are used to correlate printhead trajectory with print defect density.

SEM

absorption

defect

print


Input: There is a slight increase in X-ray scattering, hence print defect density, at regions with high curvature.Two X-ray interferometry techniques were used: stepped-grating and single-shot.

X-ray

X-ray

print

defect

interferometry


Input: As currently developed, stepped-grating has the larger field-of-view—examination of an entire test object—whilst single-shot has the potential for real-time, in situ measurement of the printing process within 1 mm of the printhead.

As

in situ

printing process

mm


Input: Efficient generation of freeform TPMS porous scaffolds.

freeform

porous scaffolds


Input: Hierarchical scaffold construction based on fractal sheet TPMSs.

scaffold

construction

sheet


Input: Porosity distribution manipulation according to CT images.

Porosity

distribution

CT


Input: The external geometry design and manipulation of internal porosity distribution according to the actual application demands are the main challenges of scaffold generation; moreover, computational efficiency is a key factor that should be considered.

geometry

distribution

computational efficiency

design

scaffold

porosity

be


Input: This paper proposes efficient generation strategies for constructing internal porous architectures by using triply periodic minimal surfaces (TPMSs) and external freeform shapes through T-spline surfaces.

porous

triply periodic minimal surfaces

freeform

surfaces


Input: After discretizing the geometries as slicing contours, TPMSs can be efficiently extracted using the intersection-interpolation method in 2D space, and then be offset as infill areas of sheet solids.

geometries

extracted

as

be

be

as

sheet

contours

areas


Input: Based on the proposed fractal sheet TPMSs, hierarchical scaffolds are further generated using the refined constrained Delaunay triangulation method to construct multiscale pores.

sheet

scaffolds

pores


Input: The porosity features can be conveniently controlled in 2D space according to the actual computed tomography images.

porosity

be

computed tomography


Input: Eventually, the resulting infill areas can be directly fabricated as scaffolds by additive manufacturing technology.

infill areas

be

as

fabricated

additive manufacturing


Input: Several experimental instances validate the effectiveness and efficiency of the proposed strategies.

experimental

effectiveness


Input: Additive manufacturing allows design freedom and reduces the cost to manufacture a complex form.

Additive manufacturing

design freedom

manufacture


Input: Prefabrication can be more time-efficient than additive manufacturing.

be

additive manufacturing


Input: Schedule shortening is not the main advantage of Additive manufacturing in construction.

Additive manufacturing

construction


Input: A breakeven point should be determined to choose the manufacturing method that suits best the need.

be

manufacturing


Input: The objective of this paper is to present a reflection on the use of Additive manufacturing in construction.

reflection

Additive manufacturing

construction


Input: In this research examples from manufacturing industries are presented.

research

manufacturing

industries


Input: Some Advantages of additive manufacturing in industry were identified.

additive manufacturing

industry


Input: Relevant cases used to promote AM for construction are: building rate improvement and schedules shortening.

AM

construction


Input: Firstly, a comparison between construction and manufacturing industry was presented.

construction

industry

manufacturing


Input: Secondly, Design and Building rate for construction were studied using data from a French construction company.

Design

construction

construction

company

data


Input: Finally a comparison was made between conventional processes and Additive manufacturing.

processes

Additive manufacturing


Input: Conventional processes included prefabrication and casting on site.

processes

casting


Input: Results showed that pre-casting may be faster than AM in some cases.

be

AM


Input: Time saving is not necessary the best advantage from applying additive manufacturing to construction.

additive manufacturing

construction


Input: Leveraging the technology's unique ability to selectively place multiple materials throughout a part volume, the authors demonstrate a new approach for the fabrication of a new physical security feature for additively manufactured parts.

technology

materials

volume

fabrication

additively manufactured

feature


Input: Specifically, the authors create photopolymer suspensions featuring quantum dots–a nanoparticle that absorbs ultraviolet light and emits light in the visible spectrum–that are then embedded into objects created by PolyJet material jetting.

photopolymer

ultraviolet light

PolyJet material jetting


Input: While the quantum dots appear ordered at the macroscale, their stochastic arrangement at the microscale (via the inkjetted droplet) provide the randomness necessary to serve as the key element of a Physical Unclonable Function, essentially transforming the 3D printed object itself as an anti-counterfeiting system.

macroscale

stochastic

microscale

droplet

as

element

as

3D printed


Input: In this work the authors explore the effects of quantum dot loading on optical signatures of the nanoparticles in the photopolymer matrix.

optical

nanoparticles

photopolymer


Input: Quantum dot loadings as low as 5 × 10−3 wt.% can be detected inside the object with a fluorescent microscope, while this same concentration is invisible to the naked eye.

as

as

be

microscope


Input: By adjusting the magnification of the fluorescent microscope, we demonstrate the feasibility of a new paradigm for three-dimensional security patterns.

magnification

feasibility

three-dimensional

microscope


Input: The adaptation of inkjet technology for additive manufacturing (AM) enabled the highest standards of print speed and print resolution in the industry.

inkjet

additive manufacturing

AM

print

standards

print resolution

industry


Input: However, inkjet printheads impose strict limitations on ink properties.

inkjet

ink


Input: Ink compositions ex volatility, rehydration, surface tension, chemical stability, abrasiveness, and electrical properties that deviate from printhead specifications shorten its service life.

Ink

surface tension

chemical stability

electrical properties

service life

specifications


Input: Frequent and complex maintenance procedures are necessary, but replacement is the only solution to declining print quality, accruing heavy maintenance costs.

solution

print quality


Input: This is especially limiting for AM as part quality and properties are closely dependent on ink composition.

AM

quality

properties

composition

ink


Input: We propose an ink deposition system designed for robustness by implementing modular and dedicated components.

ink

deposition

modular

designed

robustness

components


Input: The system deposits ink in a continuous jet.

ink


Input: We find optimal process parameters and evaluate system performance in comparison to inkjet and material extrusion (ME).

optimal process

performance

inkjet

material extrusion


Input: The system produces line widths between 0.3-0.5mm, indicating print resolution capabilities are comparable to commercial ME systems.

print resolution


Input: Sandwich structures are extensively used in aviation industries to reduce the overall weight of the system.

Sandwich structures

industries

weight


Input: Although the mechanical behavior of these structures has been widely studied, the performance of core shape in vibration response has been minimally explored.

mechanical

performance

core


Input: This study focuses on understanding the various influences of sandwich structures considering the following parameters: (i) nature of core shape, (ii) number of infill shapes, and (iii) orientation of cores, which affect the dynamic behavior of sandwich structures.

sandwich structures

sandwich structures

parameters

orientation

dynamic

core

cores

infill


Input: Nine sandwich structures comprising three different core shapes, hexagon, triangle, and square shapes, in three different orientations, namely 0°, 45°, and 90°, were considered for the present study.

sandwich structures

core

orientations


Input: These structures in the beginning were put by modal analysis using finite element method (FEM).

finite element method

FEM


Input: All the nine structures were printed using the fused deposition method to validate the FEM findings, while the DEWE soft data acquisition system was used to estimate the modal parameters (i) natural frequency and (ii) damping ratio.

fused deposition

FEM

parameters

data acquisition system


Input: This study demonstrates that although the square core orientated at 0° exhibited superior stiffness in bending loads, the hexagonal core orientated at 0° displayed an admirable combination of both stiffness and damping properties.

core

core

stiffness

stiffness

bending

hexagonal

properties


Input: Additive manufacturing shows an intrinsic compatibility with building in extra-terrestrial colonization.

Additive manufacturing


Input: The use of raw materials found in situ can drastically reduce the complexity of the material supply chain.

raw materials

material

in situ

complexity


Input: Laser Powder Bed Fusion (LPBF) is a flexible option for producing components starting from powder feedstock.

Laser Powder Bed Fusion

LPBF

components

powder feedstock


Input: This work addresses the processability of lunar highlands regolith simulant NU-LHT-2 M by Laser Powder Bed Fusion on an open prototypal system.

Laser Powder Bed Fusion


Input: The investigation into the influence of process parameters and different base plate materials (carbon steel, self-supporting deposition and refractory clay) was enabled by the in-house developed LPBF machine.

process parameters

materials

deposition

carbon steel

clay

self-supporting

refractory

LPBF


Input: The process feasibility window for multi-layer deposition was determined on the refractory clay base plate which ensured stable deposition.

process feasibility

deposition

deposition

refractory

clay


Input: Finally, process parameters were studied to produce multi-layer cubical samples which were further analysed for their mechanical properties.

process parameters

samples

mechanical properties


Input: Specimens presented compressive yield stress values in excess of 31.4 MPa and micro hardness values in excess of 680 HV, showing the potential of the technology for the deposition of lunar regolith components.

yield stress

hardness

MPa

technology

deposition

components


Input: Carbon fiber reinforced polymer (CFRP) composite is known for its high stiffness-to-weight ratio and hence is of great interest in several engineering fields such as aerospace, automotive, defense, etc.

Carbon fiber

polymer

composite

as

engineering

aerospace

automotive


Input: However, such a composite is not suitable for energy dissipation as failure occurs with very little or no plastic deformation.

composite

as

plastic deformation


Input: Herein, we present an extendable multi-material projection microstereolithography process capable of producing carbon-fiber-reinforced cellular materials that achieve simultaneously high specific stiffness and damping coefficient.

multi-material

microstereolithography

cellular materials

specific stiffness


Input: Inspired by the upper bounds of stiffness-loss coefficient in a two-phase composite, we designed and additively manufactured CFRP microlattices with soft phases architected into selected stiff-phase struts.

composite

designed

additively manufactured

struts


Input: Our results, confirmed by experimental and analytical calculations, revealed that the damping performance can be significantly enhanced by the addition of only a small fraction of the soft phase.

experimental

performance

fraction

phase

be


Input: The presented design and additive manufacturing strategy allow for optimizing mutually exclusive properties.

design

additive manufacturing

properties


Input: As a result, these CFRP microlattices achieved high specific stiffness comparable to commercial CFRP, technical ceramics, and composites, while being dissipative like elastomers.

As

ceramics

composites

elastomers

specific stiffness


Input: This paper presents an experimental approach to investigate the effects of variation in the process parameter settings, found commonly in most fused deposition modelling printers, on the geometrical properties of the printed parts.

experimental

variation

process parameter

fused deposition

properties

printers


Input: A benchmark component was designed to include simple geometric features which allows for measurement for both dimensional accuracy and geometric characteristics.

benchmark

designed

simple

measurement

dimensional accuracy


Input: Taguchi’ s design of experiment statistical approach was used to establish the relationship between varying process parameter settings on the geometrical properties of the benchmark component.

s

design of experiment

process parameter

properties

benchmark


Input: The critical process parameters affecting both the dimensional accuracy and geometric characteristics are identified and the theoretical optimum print settings were found.

process parameters

theoretical

dimensional accuracy

print


Input: Additive manufacturing (AM) is a key enabler for architectured lattice materials, because of the geometric complexity of parts that can be produced.

Additive manufacturing

AM

lattice

complexity

be


Input: Recent advancements in AM have enabled rapid production speeds, high spatial resolution, and a variety of engineering polymers.

AM

production

resolution

engineering


Input: An open question remains whether production grade AM can accurately and repeatably produce lattice parts.

production

AM

accurately

lattice


Input: This study presents design, production, and mechanical property testing of hexagonal lattice parts manufactured using continuous liquid interface production (CLIP) based AM.

design

hexagonal

production

continuous liquid interface production

CLIP

AM

mechanical property

manufactured


Input: We printed and tested 84 parts, in three polymer materials having relative density ranging from 0.06 to 0.23.

polymer materials

relative density


Input: Lattice wall structures were reliably printed when truss aspect ratio was in the range 5 to 20 and wall thicknesses were 0.35 or 0.5 mm.

Lattice

truss

aspect ratio

wall thicknesses

range

mm


Input: The printed lattice parts, each comprising hundreds of slender walls, were measured using high resolution optical scanning.

lattice

scanning

high resolution


Input: The images were analyzed to evaluate the difference between the printed parts and their designs, and the effect of geometric deviations on the mechanical behavior.

images

designs

mechanical


Input: The measured elastic moduli of the printed parts are close to the values expected from the materials specifications.

elastic moduli

materials


Input: The measured strength of the printed parts deviates by 7% from the behavior predicted from the scanned geometry.

strength

predicted

geometry


Input: The failure mode of the printed structures depends upon the material and part geometry.

failure mode

material

geometry


Input: To our knowledge, this is the largest study on the accuracy and performance of AM lattice parts, and the first study of its type for lattice parts made using CLIP.

accuracy

performance

lattice

AM

CLIP


Input: Over the past two decades, additive manufacturing has opened a new window of opportunities in fabricating complex porous matrix structures such as cellular solids.

additive manufacturing

fabricating

porous

as


Input: Several factors including design, material and process parameters can selectively be varied to tailor the porous properties of products based on the intended application.

design

material

be

process parameters

porous


Input: This article addresses the effect of variable throughout layer thickness configuration in the binder-jet additive manufacturing of titanium structures for orthopedic applications.

layer thickness

configuration

additive manufacturing

titanium


Input: Two layer thicknesses of 80 and 150 μm are selectively controlled inside of each titanium sample with four different configurations.

layer thicknesses

titanium

sample


Input: Several studies were performed, including shrinkage analysis, porosity measurements, and mechanical compression tests to quantify the effect of layer thickness on part quality and mechanical properties.

shrinkage

quality

mechanical properties

porosity

mechanical

compression tests

layer thickness


Input: The results of the porosity measurement revealed that there is about 5% variation among the samples with different layer thickness configuration.

porosity

measurement

variation

samples

configuration

layer thickness


Input: Bulk porosity values obtained from micro computed tomography (μCT) scan data placed the bulk porosity of the samples combining more than one layer thickness, in between of the results for control specimens, which were manufactured by applying a single layer thickness throughout the samples.

Bulk porosity

bulk porosity

computed tomography

data

samples

manufactured

samples

layer thickness

layer thickness


Input: Mechanical properties did not show any significant variation, which is attributed to the low range of the porosity deviation (less than 5%).

Mechanical properties

variation

range

porosity


Input: The highest Young’ s modulus of 3.50 ± 0.4 GPa and yield stress of 175 ± 25 MPa were obtained from analysis of the data achieved from the compression test.

s

GPa

yield stress

MPa

data

compression test


Input: Additive manufacturing (AM) techniques provide significant advantages over conventional subtractive manufacturing techniques in terms of the wide range of part geometry that can be obtained.

Additive manufacturing

AM

subtractive manufacturing

range

geometry

be


Input: Powder delivery is a process that occurs thousands of times during the AM build process, consequently assessment of delivery quality would be advantageous in the process in order to provide feedback for process control.

Powder

be

process

process

quality

process

process control

AM

feedback


Input: This paper presents an in-situ quantitative inspection technique for assessing the whole of the powder bed post raking, by using fringe projection profilometry.

in-situ

inspection

powder bed


Input: In order to increase accuracy and traceability of the inspection technique, an accepted fringe projection method, is enhanced using a novel surface fitting algorithm employed to reduce the influence of phase error and random noise during calibration.

accuracy

inspection

surface

algorithm

phase error

calibration


Input: A simulation was conducted to verify the accuracy of the proposed system calibration.

simulation

accuracy

calibration


Input: The proposed in-situ inspection technique has been applied in an Electron Beam Powder Bed Fusion (PBF-EB) machine, also known as Electron Beam Melting (EBM).

in-situ

Electron Beam

Bed Fusion

EBM

machine

Beam

as


Input: Some examples of melting edge swelling and excessive powder delivery due to rake damage during a real part build are used to demonstrate the system capability on the actual EBM machine.

melting

EBM

swelling

powder

damage

build


Input: Experimental results demonstrate that powder defects can be efficiently inspected and the results used as feedback information in a build process.

Experimental

defects

powder

be

as

build


Input: The Big Area Additive Manufacturing (BAAM) system can print structures on the order of several meters at high extrusion rates, thereby having the potential to significantly impact automotive, aerospace and energy sectors.

Area

extrusion rates

Additive Manufacturing

print

impact

automotive

aerospace


Input: The functional use of such parts, however, may be limited by mechanical anisotropy, in which the strength of printed parts across successive layers in the build direction (z-direction) can be significantly lower than the corresponding in-plane strength (x-y directions).

be

be

mechanical anisotropy

strength

in-plane strength

build direction

z-direction


Input: This has been primarily attributed to poor bonding between printed layers since the lower layers cool below the glass transition temperature (Tg) before the next layer is deposited.

bonding

glass transition temperature

Tg

layer


Input: Therefore, the potential of using infrared heating is considered for increasing the surface temperature of the printed layer just prior to deposition of new material to improve the interlayer strength of the components.

infrared

surface

deposition

interlayer strength

heating

layer

material

components


Input: This study found significant improvements in bond strength for the deposition of acrylonitrile butadiene styrene (ABS) reinforced with 20% chopped carbon fiber when the surface temperature of the substrate material was increased from below Tg to close to or above Tg using infrared heating.

bond strength

deposition

reinforced

surface

infrared

acrylonitrile butadiene styrene

ABS

carbon fiber

substrate material

Tg

Tg

heating


Input: The use of Magnetic Resonance Imaging (MRI) for monitoring, studying and performing output quality measurements of the acrylate-based polymeric patterns manufactured using stereolithography (SL) was introduced in this work.

Imaging

quality

manufactured

stereolithography

SL


Input: The effects of build parameters and humid environment on sample homogeneity, distribution of crosslink density, stability and defect formation were examined.

build parameters

sample

distribution

defect

density

stability


Input: The spatial resolution of the method was found to be sufficient to identify patterns according to the build parameters used and to detect specific hatch-predicted crosslink density variations.

resolution

build parameters

be

density


Input: Qualitative information obtained using MRI visualisation was supplemented by quantitative measurements of Nuclear Magnetic Resonance (NMR) relaxation times and 1H NMR spectra.

Qualitative

Nuclear Magnetic Resonance

quantitative measurements

NMR

NMR


Input: NMR spectroscopy confirmed the identity of the chemical composition among the patterns and showed that the crosslink density variation observed via spatially resolved T2-profiles stems from the difference of the build parameters.

NMR

chemical composition

density

build parameters


Input: Different types of defects in the samples were observed and classified; some defects originated from local matrix continuity failures (partially cured resin trapping within the polymer or bubbles formation), while other defects were found in the form of bulk layering.

defects

samples

defects

defects

cured

polymer


Input: MRI visualisation coupled with relaxometry and 1H spectroscopy of patterns during their interaction with humidity allowed tracking water distribution inside the sample and observing effects of swelling, fracturing and chemical decomposition.

spectroscopy

distribution

sample

swelling

decomposition


Input: As a result, the approach presented in this work improves the output quality control and current testing techniques, provides insight how physical properties of the 3D parts are affected by different technical parameters, and eventually can help the use of SL technologies for a variety of applications.

As

quality control

parameters

testing

physical properties

3D parts

SL


Input: Additive manufacturing (AM) is evolving from rapid prototyping to production of structural components.

Additive manufacturing

AM

production

rapid prototyping

structural components


Input: The widespread application of AM demands a high level of mechanical performance from these components, and it is therefore essential to improve feedstock material in order to meet these mechanical expectations.

AM

mechanical

mechanical

components

feedstock material


Input: However, compared to traditional manufacturing techniques, the mechanical properties of AM materials and their resulting components are not well understood.

traditional manufacturing

mechanical properties

AM materials

components


Input: In this study, we investigated the processability, microstructure, and mechanical performance of twin-screw compounded short carbon fiber reinforced polyphenylene sulfide (PPS) pellets as a feedstock material for big area AM (BAAM).

microstructure

pellets

mechanical

short carbon fiber reinforced polyphenylene sulfide

as

feedstock material

area

AM


Input: The performance of the AM components was compared to that of traditional processing methods, namely injection molding (IM) and extrusion-compression molding (ECM).

performance

AM

injection molding

molding

ECM


Input: It was found that the AM composites exhibited 118% lower tensile strength and 55% lower tensile modulus when compared to traditional injection molding composite specimens; however, AM composites exhibited comparable properties to ECM composites.

AM

injection molding

AM

ECM

tensile strength

tensile

composite

composites

properties


Input: This response was attributed to highly aligned fibers in IM and AM samples.

fibers

AM


Input: However, the AM composites contained porosity (15.5% volume), which reduced their mechanical properties in comparison to ECM composites.

AM

ECM

porosity

volume

mechanical properties

composites


Input: The IM process showed the maximum amount of fiber attrition with minimum porosity (0.007% volume), while the ECM process exhibited the least fiber attrition with 4.3% volume porosity.

process

volume

volume

fiber

fiber

porosity

porosity

ECM


Input: Composite manufacturing processes adapted for assisted-additive manufacturing (AM) have recently been proposed.

Composite manufacturing

manufacturing

AM


Input: Extrusion-based AM utilizes shear-driven alignment in producing printed structures where polymers and fibers naturally align parallel to the material flow.

AM

polymers

fibers

material


Input: Convergent flow geometries become the dominant processing route for thermoplastic-melts and thermoset polymer extrusions.

geometries

polymer extrusions


Input: For rotational fibers, the phenomenon known as Jeffrey orbits poses issues during extrusion through a convergent channel, resulting in a randomized fiber architecture.

fibers

as

fiber

extrusion

channel

architecture


Input: Methods of minimizing Jeffrey orbits include the application of an additional external force such as a magnetic field to arrest or counteract the rotation.

force

magnetic field

as


Input: This work explores a combination of magnetic forces in conjunction with adjusted channel geometries using theory and experimental observations.

forces

experimental

channel


Input: The findings suggest the ability to alter fiber orientation in flow in a 300 cP viscosity matrix by modifying the extrusion channel geometry.

fiber orientation

viscosity

extrusion

channel


Input: Additive Manufacturing (AM) has largely relieved the design freedom of functional parts.

Additive Manufacturing

AM

design freedom


Input: Topology optimization has been widely used to design lightweight structures fabricated by AM.

Topology optimization

design

fabricated

AM


Input: In this paper, a general design method is proposed to design solid lattice hybrid structures.

design

design

lattice


Input: An optimization algorithm is used in this method that can generate a functionally graded heterogeneous lattice structure connecting the solid part.

optimization algorithm

functionally graded

lattice structure


Input: The manufacturability can be improved due to the lattice structure supporting the overhangs.

manufacturability

be

lattice structure

overhangs


Input: A hybrid element model is used to simulate the mechanical performance and optimize the material distribution of the lattice structure.

element

material

mechanical

distribution

lattice structure


Input: To validate the design theory and the advantage of the hybrid structure, a three-point bending beam is designed by the proposed method and the existing methods.

design

designed

structure

three-point bending

beam


Input: Both the simulation result and the experimental result show that the hybrid structure has a higher stiffness, yield strength, and critical buckling load than the pure solid structure and the pure lattice structure.

simulation

experimental

structure

structure

stiffness

yield strength

buckling load

lattice structure


Input: Advancements in distributed recycling technologies now allow for on-demand reconstitution of traditionally neglected MRE pouch waste into useful appliances via material extrusion additive manufacturing.

recycling

material extrusion additive manufacturing


Input: In this work, we demonstrate recycling of MRE pouch materials through a combined compounding, filament extrusion, and fused filament fabrication (FFF) additive manufacturing protocol.

recycling

materials

filament

extrusion

fused filament fabrication

FFF

additive manufacturing


Input: Mechanical properties and barrier properties of additively manufactured structures were evaluated through tensile testing and water vapor transmission testing, respectively, and found to be comparable to the native pouch materials.

Mechanical properties

properties

materials

additively manufactured

tensile testing

transmission

testing

be


Input: Differential Scanning Calorimetry and Thermogravimetric Analysis of the extruded filament and printed materials were contrasted with native pouch materials, showing minimal effects of the manufacturing process on critical thermal transitions in the polymer.

Scanning

materials

materials

Thermogravimetric Analysis

extruded

manufacturing process

polymer


Input: To reduce the lead time, polymer fuel tanks could be toollessly produced using additive manufacturing (AM) technologies.

lead time

polymer

be

additive manufacturing

AM

technologies


Input: Detailed knowledge of the performance of AM polymers is essential for the design and development of such components.

performance

AM

design

components


Input: In instrumented static (0.01 mm/s) and dynamic (2.5 m/s) three-point bending and puncture tests, the impact behaviors of polyamide and methacrylate-based photopolymer test specimens were compared.

dynamic

impact

three-point bending

polyamide

photopolymer


Input: The polyamide test specimens were produced by laser sintering and multijet fusion, and the photopolymer test specimens were produced by a hot lithography process.

polyamide

photopolymer

laser sintering

fusion

lithography


Input: Fractography was performed using stereo light and scanning electron microscopy to investigate the fracture surface morphology.

Fractography

scanning electron microscopy

fracture

morphology


Input: The test results were used to analyze the relationships among the surface roughness, shear modulus, and glass transition temperature.

surface roughness

shear modulus

glass transition temperature


Input: The AM polymers revealed comparable force–displacement behaviors in a static three-point bending test, but their impact behaviors differed greatly.

AM

three-point bending test

impact


Input: The obtained results highlight that the impact performance of AM polymers is an essential design variable for fluid-containing parts.

impact

AM

design


Input: This investigation focuses on geometric parameters of nozzles used in Fused Filament Fabrication.

parameters

nozzles

Fused Filament Fabrication


Input: They are mainly responsible for the extrusion force.

extrusion


Input: Typical nozzles are made of brass and feature a decrease in diameter from an entry channel to a capillary with a conical section in between.

nozzles

brass

feature

diameter

channel


Input: Commercially available and custom nozzles with various of these parameters were investigated on a test stand using Polylactic Acid (PLA) filament.

nozzles

parameters

Polylactic Acid

PLA

filament


Input: All nozzles exhibit a common behavior.

nozzles


Input: The extrusion force rises linearly with increasing filament feed velocity.

extrusion

filament

feed


Input: Here, unmolten plastic reaches the nozzle.

plastic

nozzle


Input: This characteristic is dependent on extrusion temperature and geometric parameters of the nozzles.

extrusion

parameters

nozzles


Input: Different capillary lengths were used to determine the entry pressure loss at different filament feed velocities.

pressure

filament

feed


Input: The material and coating of the nozzles had no significant influence on extrusion force.

material

coating

nozzles

extrusion


Input: A higher thermal mass, two conical sections or two entry channels have a positive effect on extrusion forces and maximum filament feed velocities, thus maximal build rate.

extrusion

filament

feed

build rate


Input: Multi-material additive manufacturing enables high-performance heterogeneous design at the mesoscale, through which bulk parts can be engineered to adapt to complex loading conditions.

Multi-material additive manufacturing

heterogeneous

mesoscale

design

be


Input: The optimization of multi-material parts relies on accurate forward prediction, which is challenging to achieve owing to the complex processing conditions in additive manufacturing and the resultant uncertainties in material properties.

optimization

multi-material

prediction

material properties

accurate

additive manufacturing


Input: To address these limitations, here we present a new model calibration and model selection framework based on the high dimensional, local-scale deformation data.

model calibration

model

framework

deformation data


Input: By matching the pixel-level deformation data from digital image correlation experiments and constitutive modeling, the presented framework enables more accurate prediction and significant reduction of the prediction uncertainties, as compared to the single material calibration approach that is widely used in additive manufacturing.

deformation data

digital image correlation

framework

reduction

prediction

calibration

modeling

accurate

as

material

additive manufacturing


Input: In turn, this enables quantitative comparison of the candidate models, so the most accurate and computationally efficient constitutive model can be selected for forward prediction in heterogeneous material design.

quantitative

model

prediction

heterogeneous

accurate

be

design


Input: The advantages of the framework are demonstrated using a multi-polymer system manufactured by dual-extrusion additive manufacturing, which consists of two constituent materials with dramatically different deformation behaviors.

framework

manufactured

materials

deformation

additive manufacturing


Input: Despite the potential benefits of photopolymerization-based additive manufacturing, photochemical reactions in free-radical polymerization rarely proceed to completion, leading to the accumulation of residual monomer in polymer networks.

photopolymerization-based

residual

additive manufacturing

polymerization

photochemical

monomer

polymer


Input: In the absence of residual methyl methacrylate, other potentially toxic acrylic esters were observed thus emphasizing the need to thoroughly scrutinize additively manufactured dental devices prior to their use.

residual

acrylic

additively manufactured


Input: In the long term, standards for medical devices in dentistry could be revised to reflect the current trends in biomaterials and precursors they are generated from.

standards

trends

medical devices

dentistry

be

biomaterials


Input: The tensile strength and strain properties as well as failure modes in silicone dumbbell specimens fabricated by extrusion-based additive manufacturing are investigated.

tensile strength

strain

properties

fabricated

as

as

silicone

additive manufacturing


Input: Effects of process parameters, specifically the infill direction (0°, ±45°, and 90° relative to the tensile direction) and adjacent line spacing on the void formation and ultimate tensile strength are studied and compared to the baseline of stamped silicone specimens.

process parameters

void

infill

tensile

ultimate tensile strength

silicone


Input: The additive manufactured specimens with ±45° and 90° infill direction and either the minimal or small void extrusion configuration had the strongest ultimate tensile strength (average ranged from 1.44 to 1.51 MPa).

additive manufactured

extrusion

infill

void

configuration

average

MPa

ultimate tensile strength


Input: This strength is close to that of the sheet stamped specimens which have an average ultimate tensile strength of 1.63 MPa.

strength

tensile strength

sheet

average

MPa


Input: As the void size became larger and more elongated in shape, the average ultimate tensile strength significantly reduced to 1.15 and 0.90 MPa for specimens with ±45° and 90° infill direction, respectively.

As

void

average

MPa

tensile strength

infill


Input: Counterintuitively, specimens with 0° infill direction were consistently the worst performing due to the tangency voids and poor edge surface finish resulting from the toolpath.

infill

toolpath

voids

surface finish


Input: We show that, to maximize ultimate tensile strength of silicone parts made by extrusion-based additive manufacturing, it is important to select process parameters which minimize the elongated voids, infill tangency voids, and surface edges.

ultimate tensile strength

silicone

additive manufacturing

process parameters

voids

voids

surface

infill


Input: If these conditions can be achieved, the infill direction does not play a significant role in tensile strength of the tensile specimen.

be

infill

tensile strength

tensile specimen


Input: As part of a larger study on the laser sintering (LS) of nano-composite structures for biomedical applications, a wet mixing method was used to coat Polyamide 12 (PA12) particles with nano-hydroxyapatite (nHA).

As

Polyamide 12

laser sintering

biomedical applications

mixing

particles


Input: The addition of nHA significantly affected powder processability due to laser absorption and heat transfer effects which led to part warping.

powder

laser

absorption

heat transfer

warping

led


Input: Nano-composites containing 0.5–1.5 wt% nHA were successfully produced and tensile testing showed that 0.5 wt% nHA provided the greatest reinforcement with a 20% and 15% increase in modulus and strength respectively.

tensile testing

reinforcement

strength


Input: However, the elongation at break had significantly declined which was likely due to the formation of nHA aggregates at the sintering borders following the processing of the coated powders despite being initially well dispersed on the particle surface.

elongation

aggregates

sintering

coated

particle


Input: An intelligent optimization system is proposed to establish quantitative relationships between process parameters and multiple optimization objectives, including mechanical properties, productivity, energy efficiency, etc.

optimization

quantitative

process parameters

optimization

mechanical properties

productivity


Input: Contour maps of operation window, productivity and energy efficiency can be developed to predict optimal parameters by considering the constraints of mechanical properties and material degradation.

Contour

productivity

parameters

mechanical properties

degradation

be

material


Input: Using a facile data-driven approach, the relationships between process parameters and optimization objectives can be utilized in the process optimization and material selection.

process parameters

optimization

process optimization

be

material


Input: Powder bed fusion (PBF) represents a class of additive manufacturing processes with the unique advantage of being able to fabricate functional products with complex three-dimensional geometries.

Powder bed fusion

PBF

additive manufacturing processes

fabricate

three-dimensional geometries


Input: PBF has been broadly applied in highly value-added industries, including the biomedical device and aerospace industries.

PBF

industries

biomedical

aerospace industries


Input: However, it is challenging to construct a comprehensive knowledgebase to guide material selection and process optimization decisions to satisfy the product standards of various industries based on a poor understanding of process-structure-property/performance relationships for each type of thermoplastic.

material

thermoplastic

process optimization

standards

industries


Input: In this paper, an intelligent optimization system is proposed to establish quantitative relationships between process parameters and multiple optimization objectives, including mechanical properties, productivity, energy efficiency, and degree of material degradation.

optimization

quantitative

process parameters

optimization

mechanical properties

productivity

degradation

material


Input: Polyurethane is considered as a representative thermoplastic because it is sensitive to thermal-induced degradation and has a relatively narrow process window.

Polyurethane

as

thermoplastic

degradation

process


Input: Material and powder properties as functions of temperature are investigated using systematic material screening.

Material

powder

as

material

temperature


Input: Numerical models are created to analyze the interactions between laser beams and polymeric powders by considering the effects of chamber thermal conditions, laser parameters, temperature-dependent properties, and phase transitions of polymers, as well as laser beam characteristics.

laser beams

properties

phase

powders

polymers

as

as

laser

beam


Input: The theoretically predicted features of melting pools are validated experimentally and then utilized to develop quantitative relationships between process parameters and multiple optimization objectives.

predicted

quantitative

process parameters

optimization

melting


Input: The established relationships can guide process parameter optimization and material selection decisions for polymer PBF.

process parameter

optimization

material

polymer

PBF


Input: Additive manufacturing (AM) is emerging as a promising technology to fabricate cost-effective, customized functional parts.

Additive manufacturing

AM

fabricate

as

technology


Input: Designing such functional, i.e., load bearing, parts can be challenging and time consuming where the goal is to balance performance and material usage.

be

material

performance


Input: Topology optimization (TO) is a powerful design method which can complement AM by automating the design process.

Topology optimization

design

AM

design process


Input: However, for TO to be a useful methodology, the underlying mathematical model must be carefully constructed.

be

be

methodology

mathematical


Input: Specifically, it is well established that parts fabricated through some AM technologies, such as fused deposition modeling (FDM), exhibit behavioral anisotropicity.

fabricated

deposition modeling

AM technologies

FDM

as


Input: This induced anisotropy can have a negative impact on functionality of the part, and must be considered.

anisotropy

impact

be


Input: In the present work, a strength-based topology optimization method for structures with anisotropic materials is presented.

topology optimization

anisotropic


Input: More specifically, we propose a new topological sensitivity formulation based on strength ratio of non-homogeneous failure criteria, such as Tsai-Wu.

topological sensitivity

failure

strength

as


Input: The rapid transition of the Fused Filament Fabrication (FFF) Additive Manufacturing (AM) process from small scale prototype models to large scale polymer deposition has been driven, in part, by the addition of short carbon fibers to the polymer feedstock.

transition

process

prototype

deposition

Fused Filament Fabrication

FFF

Additive Manufacturing

AM

polymer

short carbon fibers

polymer feedstock


Input: The addition of short carbon fibers improves both the mechanical and thermal properties of the printed beads.

short carbon fibers

mechanical

thermal properties

beads


Input: The improvements to the anisotropic mechanical and thermal properties of the polymer feedstock are dependent on the spatially varying orientation of short carbon fibers which is itself a function of the velocity gradients in the flow field throughout the nozzle and in the extrudate during deposition flow.

anisotropic

thermal properties

orientation

deposition

polymer feedstock

short carbon fibers

extrudate

nozzle


Input: This paper presents a computational approach for simulating the deposition flow that occurs in the Large Area Additive Manufacturing (LAAM) process and the effects on the final short fiber orientation state in the deposited polymer bead and the resulting bead mechanical and thermal properties.

deposition

process

orientation

thermal properties

Area

Additive Manufacturing

short fiber

polymer

bead

bead


Input: The finite element method is used to evaluate Stokes flow for a two-dimensional planar flow field within a Strangpresse Model 19 LAAM polymer deposition nozzle.

finite element method

two-dimensional

Model

deposition

polymer


Input: A shape optimization method is employed to compute the shape of the polymer melt flow free surface below the nozzle exit as the bead is deposited on a moving print platform.

optimization

free surface

polymer melt

as

nozzle

platform

bead

print


Input: Three nozzle configurations are considered in this study.

nozzle


Input: Fiber orientation tensors are calculated throughout the fluid domain using the Folgar-Tucker fiber interaction model.

Fiber orientation

fluid

fiber

domain

model


Input: The effective bulk mechanical properties, specifically the longitudinal and transverse moduli, and the coefficient of thermal expansion, are also calculated for the deposited bead based on the spatially varying fiber orientation tensors.

mechanical properties

coefficient of thermal expansion

deposited bead

fiber orientation


Input: Fiber orientation is found to be highly aligned along the deposition direction of the resulting bead and the computed properties through the thickness of the bead are found to be affected by nozzle height during deposition.

Fiber orientation

be

be

deposition direction

bead

bead

properties

deposition

nozzle


Input: Significant improvements to the throughput of additive manufacturing (AM) processes are essential to their cost-effectiveness and competitiveness with traditional processing routes.

throughput

additive manufacturing

AM

processes


Input: Moreover, high-throughput AM processes, in combination with the geometric versatility of AM, will enable entirely new workflows for product design and customization.

AM processes

AM

workflows

product design


Input: We present the design and validation of a desktop-scale extrusion AM system that achieves a much greater build rate than benchmarked commercial systems.

design

validation

extrusion AM

build rate


Input: This system, which we call ‘FastFFF’, is motivated by our recent analysis of the rate-limiting mechanisms to conventional fused filament fabrication (FFF) technology.

fused filament fabrication

FFF

technology


Input: The FastFFF system mutually overcomes these limits, using a nut-feed extruder, laser-heated polymer liquefier, and servo-driven parallel gantry system to achieve high extrusion force, rapid filament heating, and fast gantry motion, respectively.

limits

extruder

polymer

filament

extrusion


Input: The extrusion and heating mechanisms are contained in a compact printhead that receives a threaded filament and augments conduction heat transfer with a fiber-coupled diode laser.

extrusion

heating

compact

filament

heat transfer

diode


Input: The prototype system achieves a volumetric build rate of 127 cm3/hr, which is approximately 7-fold greater than commercial desktop FFF systems, at comparable resolution; the maximum extrusion rate of the printhead is ∼14-fold greater (282 cm3/hr) than our benchmarks.

prototype

build rate

FFF

resolution

extrusion rate


Input: The performance limits of the printhead and motion systems are characterized, and the tradeoffs between build rate and resolution are assessed and discussed.

performance limits

build rate

resolution


Input: High-speed desktop AM raises the possibility of new use cases and business models for AM, where handheld parts are built in minutes rather than hours.

AM

AM

business models


Input: Adaptation of this technology to print high-temperature thermoplastics and composite materials, which require high extrusion forces, is also of interest.

technology

print

extrusion

thermoplastics

composite materials


Input: The driver for this research is the development of multi-material additive manufacturing processes that provide the potential for multi-functional parts to be manufactured in a single operation.

research

multi-material additive manufacturing

be


Input: In order to exploit the potential benefits of this emergent technology, new design, analysis and optimization methods are needed.

technology

optimization

design


Input: This paper presents a method that enables in the optimization of a multifunctional part by coupling both the system and structural design aspects.

optimization

structural design


Input: This is achieved by incorporating the effects of a system, comprised of a number of connected functional components, on the structural response of a part within a structural topology optimization procedure.

functional components

topology optimization


Input: The potential of the proposed method is demonstrated by performing a coupled optimization on a cantilever plate with integrated components and circuitry.

optimization

cantilever

components


Input: Biocompatible and biodegradable poly (lactic acid) (PLA) and hydroxyapatite (HAP) are widely used for bone repair.

Biocompatible

PLA

hydroxyapatite

bone


Input: In this study, microspheres consisting of poly (lactic acid) (PLA) and nano-hydroxyapatite (nano-HAP) were synthesized by emulsion solvent evaporation and were then used to fabricate layered parts using laser powder bed fusion (L-PBF).

microspheres

evaporation

PLA

emulsion

fabricate

laser powder bed fusion

L-PBF


Input: The effect of various parameters of the emulsion solvent evaporation technique on the size and morphology of the resulting PLA/nano-HAP microspheres was examined.

parameters

evaporation

morphology

microspheres

emulsion


Input: We also evaluated how L-PBF parameters affected the physicochemical and biological properties of the fabricated parts.

L-PBF

properties

fabricated


Input: Nano-HAP was uniformly incorporated into PLA microspheres.

PLA

microspheres


Input: Incorporation of HAP particles triggered pore formation on the microsphere surface.

particles

surface

pore


Input: Layered parts fabricated by L-PBF using these composite microspheres as a material source showed good biocompatibility and osteogenesis.

fabricated

L-PBF

composite

as

material

biocompatibility


Input: A 10 wt% of nano-HAP content in the layered part could effectively facilitate osteogenic differentiation of rat mesenchymal stem cells (rMSCs).

mesenchymal stem cells


Input: Thus, L-PBF is a promising technology that can be used for manufacturing bone-repair implants consisting of PLA/nano-HAP composites materials.

L-PBF

manufacturing

technology

be

composites

implants


Input: In additive manufacturing (AM) processes, part and process attributes are often optimized with build orientation/tool-path direction.

additive manufacturing

AM

processes

process

build


Input: Both of them may alter the layer topology and tool-path pattern which implicitly affect the part and process attributes.

layer

tool-path

pattern

process


Input: However, optimizing either build orientation or tool-path direction independently undermines the hierarchical relationship in the AM process plan and may produce a sub-optimal solution.

build orientation

tool-path

AM process

solution


Input: In this paper, an integrated framework is proposed to quantify their combined effect on the part and process attributes by analyzing the generated geometry.

framework

process

geometry


Input: The proposed methodology is designed on the basis of the layer geometries to ensure manufacturability and minimize fabrication complexity in AM processes.

methodology

geometries

manufacturability

complexity

designed

layer

fabrication

AM processes


Input: Both build orientation and tool-path/deposition direction are concurrently optimized using a Genetic Algorithm (GA).

build orientation

Genetic Algorithm

GA


Input: Multi Jet Fusion process.

Multi Jet Fusion


Input: Modelling the capillarity effect in Multi Jet Fusion technology.

Modelling

Multi Jet Fusion


Input: Multi Jet Fusion is a powder-based Additive Manufacturing technology patented by Hewlett-Packard Inc.

Multi Jet Fusion

powder-based Additive Manufacturing


Input: It is characterised by the use of lamps instead of lasers to heat and melt polymers and by fusing and detailing agents that are jetted on the polymeric particles to modify and to control their heat absorption and thus selectively melt them.

heat

melt

fusing

particles

melt

heat absorption


Input: The high production rate and excellent mechanical properties of the manufactured parts, even in comparison with Laser Sintering, together with the overall product quality make this technology effective for a production of small series of end-parts rather than functional prototypes.In the present paper, the so-called capillarity effect is investigated.

production

Laser Sintering

production

mechanical properties

manufactured

product quality

technology


Input: A benchmark geometry was designed to be affected by the capillarity effect and then manufactured by the MJF process.

benchmark

designed

be

manufactured

MJF


Input: Values of the contact angle and of the characteristic length of the capillary, which are necessary to implement the analytical model, were obtained by experimental measurements made on the benchmark geometry.As a result the capillarity effect showed a dependence on the border edge orientation.

contact

model

experimental

orientation

benchmark


Input: The comparison between calculated shapes of the plane affected by the capillarity effect through the analytical model was in accordance with the experimental measurements thus allowing a reliable prediction to be made.

model

experimental

prediction

be


Input: Experiment to identify influence factors of nozzle clogging.

Experiment

nozzle


Input: Identification of reasons causing clogging of sphere-filled polycarbonate.

polycarbonate


Input: Model for the occurrence of nozzle clogging.

Model

nozzle


Input: Mathematical viscosity model to approximate printability of materials.

Mathematical

model

materials

printability


Input: Fused filament fabrication with reinforced or filled polymers provides improved material properties compared to ordinary feedstock.

Fused filament fabrication

reinforced

material properties

polymers

feedstock


Input: A current limitation of these materials is the occurrence of nozzle clogging at higher filler contents.

materials

nozzle


Input: In this work, an experiment is designed to identify the factors causing nozzle clogging.

experiment

designed

nozzle


Input: Glass sphere-filled polycarbonate is investigated by varying nozzle and filler diameters, the resin viscosity, the filler content, and the extrusion pressure.

Glass

polycarbonate

resin

nozzle

extrusion pressure


Input: Based on these results, a model for the clogging of sphere-filled polymers is proposed.

model

polymers


Input: Last, a mathematical model is derived, which approximates the printability of filled polymers without the preparation of composites.

mathematical

printability

polymers

composites


Input: This model is based on the nozzle geometry, the filler type and content, the resin viscosity, and the printer’ s maximum extrusion force.

model

geometry

nozzle

printer

resin

s

extrusion


Input: In this study, we propose a tool-path generation approach for material extrusion-based additive manufacturing (AM) that considers the machining efficiency and fabrication precision, which are inherent drawbacks of general AM techniques compared with conventional manufacturing methods.

tool-path

material

additive manufacturing

AM

machining

fabrication

AM techniques

conventional manufacturing


Input: These three modules interact to affect the efficiency and precision of AM significantly.

precision

AM


Input: In order to find an optimal inclination, we first analyze the impacts on the fabrication efficiency and manufacturing accuracy with different inclinations.

inclination

inclinations

fabrication

manufacturing

accuracy


Input: A comparatively accurate building time model is developed subsequently to obtain the optimal tool-path inclination, but without compromising the machining precision, based on the analysis of a geometrical accuracy model.

accurate

accuracy

model

tool-path

inclination

machining


Input: The proposed approach employs different inclinations in distinct layers according to specific manufacturing scenarios and technological requirements.

inclinations

manufacturing


Input: Fused deposition modeling (FDM) is shown to be a future-oriented technology.

Fused deposition modeling

FDM

be

technology


Input: In this study, short-term creep deformation of PC-ABS parts created by FDM under different fabrication conditions was investigated using a recently innovative class of experimental design − definitive screening design (DSD) − along with graphical analysis.

creep

FDM

fabrication

experimental design

design


Input: Short-term creep experiments were conducted at prescribed combinations of FDM operating conditions, namely layer thickness, air gap, raster angle, build orientation, road width and number of contours, as per DSD matrix.

creep

FDM

layer thickness

build orientation

contours

as


Input: The results have shown that layer thickness, number of contours, raster angle and build orientation have a major effect on the creep rate of the parts.

layer thickness

build orientation

contours

creep


Input: However, road width and air gap have least impact on the creep rate of FDM processed prototypes.

impact

prototypes

creep

FDM


Input: We present the design and characterisation of a high-speed sintering additive manufacturing benchmarking artefact following a design-for-metrology approach.

design

sintering

additive manufacturing


Input: In an important improvement over conventional approaches, the specifications and operating principles of the instruments that would be used to measure the manufactured artefact were taken into account during its design process.

specifications

be

manufactured

design process


Input: With the design-for-metrology methodology, we aim to improve and facilitate measurements on parts produced using additive manufacturing.

methodology

additive manufacturing


Input: The benchmarking artefact has a number of geometrical features, including sphericity, cylindricity, coaxiality and minimum feature size, all of which are measured using contact, optical and X-ray computed tomography coordinate measuring systems.

geometrical features

cylindricity

minimum feature size

coordinate

contact

optical

X-ray computed tomography


Input: The results highlight the differences between the measuring methods, and the need to establish a specification standards and guidance for the dimensional assessment of additive manufacturing parts.

specification

additive manufacturing


Input: Low molecular weight gelators can facilitate direct writing of epoxy resin.

weight

epoxy