Input: As-printed CS-HEA showed higher strength due to high work hardenability, whereas substantial uniform ductility is associated with a combination of transformation and twinning induced plasticity during deformation.

strength

hardenability

ductility

plasticity

twinning

deformation


Input: Additionally, very low volume percent of voids (∼0.1%) along with high strength-ductility shows excellent printability of the CS-HEA using laser-based additive manufacturing.

volume

voids

printability

laser-based additive manufacturing


Input: Izod impact test specimens were fabricated via a desktop grade material extrusion 3D printer process using ABS in four build orientations.

impact test

fabricated

desktop grade

extrusion

3D printer

ABS

build orientations


Input: The 3D printed impact test specimens were examined in order to compare the effect of stress concentrator fabrication on impact test data where two methods were used to fabricate the stress concentrating notch: (1) printing the stress concentrator; and (2) machining the stress concentrator where the dimensions of the notch matched those specified in the ASTM standard D256-10.

3D printed

fabrication

fabricate

machining

stress

stress

stress

stress

impact test

data

standard

notch

dimensions

notch


Input: In both test cases, sensitivity to build orientation was also observed.

sensitivity

build orientation


Input: The sample sets with printed stress concentrators were found to be statistically similar to their counterparts with milled stress concentrators.

sample

stress

be

milled


Input: The experiment was repeated again on a commercial grade material extrusion 3D printer using ABS, PC, PC-ABS, and Ultem 9085 and differences in impact test results were observed most notably when Ultem 9085 was tested.

experiment

commercial grade

extrusion

3D printer

ABS

PC

impact test


Input: Scanning electron microscopy was utilized to perform fractograpy on impact test specimens to explore the effect of stress concentrator fabrication on the fracture surface morphology of the failed specimens.

Scanning electron microscopy

impact test

stress

fabrication

fracture

morphology


Input: The work here demonstrates the need for materials testing standards that are specific to additive manufacturing technologies; as well as concluding that all-printed impact test specimens may offer the best representation of the impact characteristics of 3D printed structures.

materials

standards

impact

additive manufacturing

3D printed

as

as

impact test


Input: In recent years 3D printing has gained popularity amongst industry professionals and hobbyists alike, with many new types of Fused Filament Fabrication (FFF) apparatus types becoming available on the market.

3D printing

Fused Filament Fabrication

FFF

industry


Input: A massively overlooked component of FFF is the requirement for a simple method to calculate the geometries of polymer depositions extruded during the FFF process.

component

FFF

simple

extruded

FFF

geometries

polymer


Input: Manufacturers have so far achieved adequate methods to calculate tool-paths through so called slicer software packages which calculate the required velocities of extrusion from prior knowledge and data.

slicer

extrusion

data


Input: Presented here is a method for obtaining a series of equations for predicting height, width and cross-sectional area values for given processing parameters within the FFF process for initial laydown on to a glass surface.

area

parameters

FFF

glass


Input: This work investigates the evolution of the tensile and structural properties of fused filament fabrication (FFF), formed polymers under gamma irradiation.

investigates

evolution

properties

tensile

fused filament fabrication

FFF

irradiation

polymers


Input: Commercial off-the-shelf print filaments of Poly (lactic acid) (PLA), Thermoplastic polyurethane (TPU), Chlorinated polyethylene elastomer (CPE), Nylon, Acrylonitrile butadiene styrene (ABS) and Polycarbonate (PC) were exposed to gamma-ray doses of up to 5.3 MGy.

print

filaments

PLA

Thermoplastic polyurethane

polyethylene elastomer

Nylon

Acrylonitrile butadiene styrene

ABS

Polycarbonate

PC


Input: The suitability of FFF-formed components made from these materials for use in radiation environments is evaluated by considering their structural properties.

components

materials

properties

radiation


Input: We identify clear trends in the structural properties of all the materials tested and correlate them with changes in the chemical structure.

trends

properties

materials

structure


Input: We find that Nylon shows the best performance under these conditions, with no change in ultimate tensile strength and an increase in stiffness.

Nylon

performance

ultimate tensile strength

stiffness


Input: However, some of our findings suggest that the effect of additives to this type of filament may result in potentially undesirable adhesive properties.

additives

filament

adhesive


Input: The organic polymer PLA was notably more radiation-sensitive than the other materials tested, showing 50% decrease in Young’ s Modulus and ultimate tensile strength at order of magnitude lower radiation dose.

polymer PLA

s

materials

ultimate tensile strength

magnitude

radiation


Input: A mechanism is proposed whereby FFF-processed components would have substantially different radiation tolerances than bulk material.

mechanism

components

radiation

material


Input: In this article, we report the synthesis of a series of multi-branched benzylidene (BI) ketone-based photo-initiators for two-photon polymerisation based 3D printing/additive manufacturing.

BI

two-photon polymerisation

manufacturing


Input: The successful fabrication of complex 3D structures at high writing speeds (up to 100 mm/s) indicated that the four-branched initiator 4-BI could potentially increase the fabrication efficiency and hence become a promising initiator for two-photon polymerisation.

fabrication

fabrication

3D structures

two-photon polymerisation


Input: A path planning methodology is proposed for FFF based on stress orientations.

path planning methodology

orientations

FFF

stress


Input: Specimens created with the stress-based path exhibit better mechanical properties.

mechanical properties


Input: Anisotropy of tool-paths leads to stress redistribution of stress components.

Anisotropy

stress

stress

components


Input: Different tool-paths are broken with variable fracture processes and surfaces.

fracture

surfaces


Input: Tool-path planning has a considerable impact on the quality of components printed by fused filament fabrication (FFF).

Tool-path

planning

fused filament fabrication

FFF

impact

quality

components


Input: This research proposes a path generation strategy based on the orientations of the maximum principal stresses.

research

orientations

principal stresses


Input: According to stress calculations from finite element analysis (FEA) of the components, tool-paths, which are programmed as parallel to the maximum principal stress directions, are constructed with the depth-first search (DFS) method and a connection criterion.

stress

principal stress

finite element analysis

components

as


Input: The Dijkstra algorithm is engaged to reduce the nozzle jump distance and shorten the production time.

algorithm

nozzle

production


Input: Stretching tests of different specimens printed with the developed path generation algorithms demonstrate that the model with the stress-based path has better mechanical performance.

algorithms

model

mechanical


Input: The digital image correlation (DIC) method and scanning electron microscopy (SEM) are employed to observe the fracture processes and fracture surfaces, respectively.

digital image correlation

DIC

fracture

fracture

scanning electron microscopy

SEM


Input: Corresponding results of DIC and SEM reveal that different path filling forms exhibit variable failure patterns because of filament anisotropy.

DIC

failure

SEM

filament

anisotropy


Input: The filling fraction is calculated and indicates that the deposition quality of the advanced path is not compromised.

fraction

deposition quality


Input: This work provides a synthesis methodology for improving the mechanical performance of 3D printing products.

methodology

mechanical

3D printing


Input: In the context of the large format additive manufacturing in ambient conditions, extrusion materials need to be thermally stable, thus short fiber-reinforced composites have been developed to tailor the thermal behavior.

additive manufacturing

extrusion

be

composites


Input: However, lack of public knowledge in material properties and dataset lead to improper processing; yielding degradation of materials during trial & error operations which not only increase cost but also reduce the quality of printed parts.

material properties

degradation

materials

error

quality

lead


Input: This research investigated neat and composite ABS filled with short carbon fiber (ABS/CF) and glass fiber (ABS/GF) using thermophysical and thermomechanical characterization techniques to generate dataset and knowledge that can be used to process materials without degrading the properties as well as achieving the quality parts in future.

research

thermomechanical

process materials

properties

quality

composite ABS

short carbon fiber

glass fiber

be

as

as


Input: Thermogravimetric analysis was performed to study the degradation behavior.

Thermogravimetric analysis

degradation


Input: Differential scanning calorimetry (DSC) analyzed the glass transition temperature (Tg) and specific heat to understand the heat dissipation of neat and composite materials.

scanning

glass transition temperature

heat dissipation

DSC

Tg

specific heat

composite materials


Input: While the Tg measured in DSC was not significantly different, the dynamic mechanical analysis showed that Tg in ABS/CF was increased due to the impeded polymer chain mobility.

Tg

DSC

Tg

dynamic mechanical analysis

polymer


Input: The thermomechanical analysis described the deformation behavior before and after the transition temperature which suggested that ABS/CF has the highest thermal stability to retain the shape at elevated temperature followed by ABS/GF and neat ABS.

thermomechanical

deformation

transition

temperature

temperature

thermal stability

ABS


Input: The findings of this article can be used during the modeling of pellet-fed large format AM and developing empirical process parameters.

be

modeling

AM

empirical

parameters


Input: The use of additive manufacturing (AM) is rapidly expanding in many industries mostly because of the flexibility to manufacture complex geometries.

additive manufacturing

AM

industries

flexibility

manufacture

complex geometries


Input: Recently, a family of technologies that produce fiber reinforced components has been introduced, widening the options available to designers.

technologies

fiber

components


Input: AM fiber reinforced composites are characterized by the fact that process related parameters such as the amount of reinforcement fiber, or printing architecture, significantly affect the tensile properties of final parts.

AM

reinforced

process

parameters

composites

as

fiber

reinforcement

architecture

tensile properties


Input: To find optimal structures using new AM technologies, guidelines for the design of 3D printed composite parts are needed.

optimal structures

design

AM technologies

3D printed


Input: This paper presents an evaluation of the effects that different geometric parameters have on the tensile properties of 3D printed composites manufactured by fused filament fabrication (FFF) out of continuous and chopped carbon fiber reinforcement.

parameters

manufactured

tensile properties

3D printed

fused filament fabrication

FFF

carbon fiber


Input: Parameters such as infill density and infill patterns of chopped composite material, as well as fiber volume fraction and printing architecture of continuous fiber reinforcement (CFR) composites are varied.

Parameters

as

composite material

as

as

continuous fiber reinforcement

composites

density

infill

volume fraction

architecture


Input: The effect of the location of the initial deposit point of reinforcement fibers on the tensile properties of the test specimens is studied.

reinforcement

fibers

tensile properties


Input: Also, the effect that the fiber deposition pattern has on tensile performance is quantified.

fiber

deposition

performance

tensile


Input: Considering the geometric parameters that were studied, a variation of the Rule of Mixtures (ROM) that provides a way to estimate the elastic modulus of a 3D printed composite is proposed.

parameters

variation

Rule of Mixtures

elastic modulus

3D printed


Input: Findings may be used by designers to define the best construction parameters for 3D printed composite parts.

be

construction

3D printed


Input: The application space for three-dimensional (3D) printing, such as fused filament fabrication (FFF), has grown significantly through the use of high-performance composite materials.

three-dimensional

as

filament

composite materials

fabrication

FFF


Input: While the mechanical, thermal, optical, and electrical properties of additive manufacturing (AM) polymer composites are being actively studied, the magnetic properties of AM parts have seen much less attention.

mechanical

optical

electrical properties

properties

additive manufacturing

AM

polymer composites

AM parts


Input: Prior research has shown that the structural print settings for FFF influence the magnetic properties of the printed part (Bollig et al., 2017).

research

properties

print

FFF


Input: However, the structural hierarchy present in the FFF process complicates a simple analysis of how these magnetic differences arise.

structural hierarchy

FFF

simple


Input: Here, a magnetic filament consisting of polylactic acid (PLA) polymer and 40 wt.% iron was used to print a variety of samples to investigate how the macroscopic sample shape and the mesoscopic infill orientation and infill percentage affects the magnetic properties.

filament

polylactic acid

PLA

polymer

iron

print

samples

macroscopic

properties

infill

infill percentage


Input: The array of samples systematically covered different aspect ratios (length: width), edge contours (rectangular vs. ellipsoidal), two infill orientations (long axis alignment vs. short axis alignment), and varying infill percentages.

samples

aspect ratios

contours

infill

infill percentages


Input: The key results show that the highest magnetic susceptibility was seen for magnetic fields applied parallel to the infill orientation.

magnetic susceptibility

magnetic fields

infill


Input: The macroscopic geometry increased the magnetic susceptibility parallel to the long axis of the sample.

macroscopic geometry

sample

magnetic susceptibility


Input: Lastly, certain factors, such as edge contours and infill percentage, only affected the magnetic susceptibility when the magnetic field was applied transverse to the infill orientation, but had no effect when field was applied along the infill direction.

as

contours

infill percentage

infill

infill

magnetic susceptibility

magnetic field


Input: Elucidating how the part shape, infill orientation, and infill percentage affects the magnetic properties of AM parts will help the community better understand how an FFF process can be utilized to make optimal magnetic components, such as transformer cores, electric motors, and electromagnetic interference shielding.

infill

infill percentage

properties

AM parts

components

cores

FFF

be

as


Input: The interface between layers has bulk-material strength.

interface

strength


Input: Filament-scale grooves reduce load-bearing capacity at the interface.

load-bearing

capacity

interface


Input: Toughness and strain-at-fracture are higher in the direction of extruded filaments.

Toughness

extruded


Input: Aspect ratio has an important effect on load-bearing capacity.

Aspect ratio

load-bearing

capacity


Input: Strain-localisation is a predominant cause of fracture, based on simulation.

fracture

simulation


Input: This study demonstrates that the interface between layers in 3D-printed polylactide has strength of the bulk filament.

interface

strength

filament


Input: Specially designed 3D-printed tensile specimens were developed to test mechanical properties in the direction of the extruded filament (F specimens), representing bulk material properties, and normal to the interface between 3D-printed layers (Z specimens).

designed

extruded

F

mechanical properties

material properties

interface


Input: A wide range of cross-sectional aspect ratios for extruded-filament geometries were considered by printing with five different LHs and five different EFWs.

range

aspect ratios

geometries


Input: Both F and Z specimens demonstrated bulk material strength.

F

material strength


Input: In contrast, strain-at-fracture, specific load-bearing capacity, and toughness were found to be lower in Z specimens due to the presence of filament-scale geometric features (grooves between extruded filaments).

load-bearing

capacity

toughness

be

extruded


Input: The different trends for strength as compared to other mechanical properties were evaluated with finite-element analysis.

trends

mechanical properties

strength

as


Input: It was found that anisotropy was caused by the extruded-filament geometry and localised strain (as opposed to assumed incomplete bonding of the polymer across the interlayer interface).

anisotropy

strain

geometry

bonding

interface

as

polymer


Input: Additionally, effects of variation in print speed and layer time were studied and found to have no influence on interlayer bond strength.

variation

bond strength

print

layer


Input: The relevance of the results to other materials, toolpath design, industrial applications, and future research is discussed.

materials

research

toolpath

design

industrial


Input: Multi-photon polymerization, like the so-called direct laser writing (DLW) technique allows for flexible additive manufacturing of three-dimensional ultra-precise structures on the micro- and nanoscale.

polymerization

additive manufacturing

direct laser writing

three-dimensional

micro-


Input: A possible application for DLW is the manufacturing of measurement standards for calibration procedures of optical measurement instruments.

manufacturing

measurement standards

calibration

optical measurement


Input: This requires flexible and high precision manufacturing of individualized geometries with high quality surfaces.

precision

manufacturing

geometries

quality


Input: However, many of the process parameters in DLW have to be selected based on experience and previous knowledge.In this article, the influence of DLW process parameters on the micro-geometry and surface roughness produced are systematically studied, and optimized in terms of printing speed and manufacturing accuracy.

process parameters

process parameters

be

surface roughness

printing speed

manufacturing

accuracy


Input: Resulting microstructures are being evaluated with different measurement techniques, i.e., a stylus instrument, SEM and AFM.

microstructures

measurement

SEM

stylus


Input: Based on optimized process parameters, a new measurement standard for the novel interferometric measurement instrument Ellipso-Height-Topometer is manufactured and examined as a case study.

process parameters

measurement standard

manufactured

case study

measurement

as


Input: As a result, it can be shown, that DLW is able to manufacture ultra-precise micro geometries in a very flexible and very fast way and satisfies the tolerances for manufacturing of the designed measurement standard.

As

be

manufacture

geometries

standard

tolerances

manufacturing

designed


Input: The spreading of molten polymer between the moving printing head and the substrate in extrusion additive manufacturing is studied.

polymer

substrate

printing head

extrusion

additive manufacturing


Input: Finite element computation and an analytical model have been used.

Finite element

computation

model


Input: The hypotheses of the analytical model are qualitatively justified by the results of the numerical computation.

model

computation


Input: The analytical calculation is a powerful tool to rapidly evaluate the relationships between processing parameters (extrusion rate, printing head velocity, gap between the printing head and the substrate) and some characteristics of the deposition (dimensions of the deposited filament, pressure at the printing head nozzle, separating force between substrate and printing head).

tool

printing head

printing head

printing head

nozzle

printing head

parameters

deposition

pressure

force

extrusion rate

substrate

filament

substrate

dimensions


Input: An isothermal hypothesis is discussed.

isothermal


Input: The viscous non-Newtonian behavior is accounted for through an approximate shear thinning power law model.

shear thinning

model

power


Input: A printing processing window is defined following several requirements: a continuous deposit, without spreading in front of the printing head, maximum and minimum spreading pressures, an upper-limit for the separating force between head and substrate.

printing head

pressures

force

substrate


Input: A heated build environment in Fused Filament Fabrication (FFF) additive manufacturing (AM) is used to promote layer bonding in printed parts and reduce the difference in temperature between the extrusion and environment decreasing the shrinkage, residual stresses, and part deformation.

build

layer

temperature

Fused Filament Fabrication

FFF

additive manufacturing

AM

extrusion

bonding

shrinkage

deformation

residual stresses


Input: A build environment capable of maintaining a high-temperature (> 200 °C) is often required to enable high-quality FFF printing of high-glass-transition, high-performance polymers such as nylon, PPSF, and ULTEM.

build

FFF

polymers

as


Input: Industrial-scale AM systems are capable of printing such polymers, as they offer a controlled, high-temperature printing environment; however, the machine cost often exceeds > $100,000.

AM

polymers

as

machine


Input: Many of these printers use bed heating rather than controlled environment heating, which can lead to inhomogeneous heat transfer and inconsistent properties.

printers

bed

heating

lead

heat transfer

properties


Input: The key barrier to offering high-temperature environments for desktop-scale FFF systems in a cost-effective manner is that the electrical components must be compatible with, protected from, or removed from environments exceeding 100 °C.To enable desktop-scale FFF printing of high-performance polymers at a low cost and high quality, the authors present a novel inverted FFF system design that provides a build environment of up to 400 °C.

FFF

FFF

FFF

electrical

components

be

polymers

quality

design

build


Input: The inverted configuration effectively isolates the system electronics from the heated build environment, which allows for the use of inexpensive components.

configuration

electronics

build

components


Input: In this paper, the authors verify the inverted design concept analytically via a computational fluid dynamics model.

design

computational fluid dynamics


Input: The concept is then experimentally validated via a comparison of the strength of PPSF components printed on the inverted desktop-scale FFF system.

experimentally validated

strength

components

FFF


Input: Additively manufactured parts made with polymer extrusion techniques can be 50–75% weaker in the z-direction (across layers) than in the x- and y-directions.

Additively manufactured

polymer extrusion

be

z-direction


Input: This is particularly a challenge when printing large-scale parts, such as with the Big Area Additive Manufacturing (BAAM) system, because layer times can exceed several minutes.

as

Area

layer

Additive Manufacturing


Input: The current work presents a method for controlling the temperature of the substrate material on the BAAM just prior to deposition using infrared heating lamps.

temperature

substrate material

deposition

infrared

heating


Input: Long layer times were also simulated by actively cooling the material following deposition of each layer.

layer

layer

cooling

material

deposition


Input: The effect of substrate temperature on the z-direction mechanical properties of 20% carbon fiber reinforced acrylonitrile butadiene styrene (ABS) was measured for an initial temperature ranging from 50 °C to 150 °C and a preheated temperature ranging from 150 °C to 220 °C.

substrate

carbon fiber

acrylonitrile butadiene styrene

ABS

z-direction

mechanical properties

temperature

temperature


Input: Infrared preheating proved to be very effective when applied to substrates that had cooled considerably, almost doubling the tensile strength and increasing the fracture toughness by a factor of 7x.

Infrared

fracture

be

tensile strength


Input: Poly-l-lactic acid (PLLA) is a bioresorbable polymer used in a variety of biomedical applications.

polymer

biomedical applications


Input: Many 3D printers employ the fused filament fabrication (FFF) approach with the ubiquitous low-cost poly-lactic acid (PLA) fiber.

3D printers

fused filament fabrication

FFF

PLA

fiber


Input: However, use of the FFF approach to fabricate scaffolds with medical grade PLLA polymer remains largely unexplored.

FFF

fabricate

medical

polymer


Input: In this study, high molecular weight PL-32 pellets were extruded into ∼1.7 mm diameter PLLA fiber.

weight

pellets

diameter

extruded

mm

fiber


Input: Melt rheometric data of the PLLA polymer was analyzed and demonstrated pseudo-plastic behavior with a flow index of n = 0.465 (< 1).

Melt

data

polymer

n


Input: Differential scanning calorimetry (DSC) was conducted using samples from the extruded fiber to obtain thermal properties.

scanning

samples

thermal properties

DSC

extruded


Input: DSC of the 3D printed struts was also analyzed to assess changes in thermal properties due to FFF.

DSC

3D printed

FFF

thermal properties


Input: The DSC and rheometric analysis results were subsequently used to define appropriate FFF process parameters.

DSC

FFF

parameters


Input: Constant porosity scaffolds were FFF 3D printed with 4 distinct laydown patterns; 0/90° rectilinear (control), 45/135° rectilinear, Archimedean chords, and honeycomb using the in-house developed custom multi-modality 3D bioprinter (CMMB).

porosity

FFF

3D printed

honeycomb


Input: The effect of laydown pattern on scaffold bulk erosion (weight loss) was studied by immersion in phosphate-buffered saline (PBS) over a 6-month period and measured monthly.

pattern

scaffold

weight

PBS


Input: Cross-sectional scanning electron microscope (SEM) images of the 6-month degraded scaffolds showed noticeable structural deterioration.

scanning electron microscope

SEM

images

scaffolds


Input: The study demonstrates successful processing of PLLA fiber from PL-32 pellets and FFF-based 3D printing of bioresorbable scaffolds with pre-defined laydown patterns using medical grade PLLA polymer which could prove beneficial in biomedical applications.

fiber

polymer

pellets

3D printing

scaffolds

medical

biomedical applications


Input: Filament printed GO structures are mechanically stable by rapid freezing in liquid nitrogen and lyiophilization.

Filament

GO

nitrogen


Input: Thermally reduced GO (rGO) structures are rapidly infiltrated with a preceramic polymer under vacuum conditions.

GO

rGO

polymer


Input: The composite structure perfectly replicates the printed GO structure.

composite structure

GO


Input: The hybrid composite structure (rGO/SiCN) shows high strength and electrical conductivity.

hybrid composite

strength

electrical conductivity


Input: Steady graphene oxide (GO) scaffolds created by direct ink writing are used to develop a silicon carbonitride (SiCN) -graphene oxide hybrid material through a preceramic polymer route.

graphene oxide

GO

ink

silicon

oxide

material

polymer

scaffolds


Input: For achieving mechanically stable GO scaffolds, the drying method is critical as the ink contains about 5 wt.% of GO, 10 wt.% of polyelectrolytes and 85 wt.% of water.

GO

as

ink

GO

drying


Input: The liquid preceramic polymer (polysilazane type) quickly infiltrates the 3D scaffolds, under vacuum conditions, entirely covering the GO network creating a replica of the original scaffold.

polymer

GO

scaffold


Input: The hybrid cellular structure -once thermally treated for GO reduction and ceramic conversion- consists of a network of reduced GO (∼10 wt.%) embedded in an amorphous SiCN matrix following the designed architecture.

cellular structure

designed

thermally treated

GO

ceramic

GO

architecture


Input: The 3D hybrid structures show notable electrical conductivity (890 S m−1 at room temperature), thermal stability and considerable strength, about 20 times higher than the single GO scaffold.

electrical conductivity

thermal stability

strength

S

GO

temperature


Input: Single-operation, hybrid-AM fabrication of form-factor free supercapacitors.

fabrication


Input: As-printed gravimetric EDLC electrode capacitance of 116.4 ±0.6 F g−1 at 10 mV s−1.

electrode

F


Input: Detailed insight into FFF and DIW processing parameters.

FFF

DIW

parameters


Input: Additive manufacturing (AM) may offer a flexible, cost-effective approach to address conventional manufacturing limitations, such as time-consuming, high work-in-progress, multi-step assembly.

Additive manufacturing

AM

conventional manufacturing

assembly

as


Input: In principle AM can also allow more novel geometric or even bespoke designs of structural and functional products.

AM

designs


Input: However, in terms of energy storage devices such as batteries and supercapacitors, the benefits of AM have not yet been explored to any significant extent.

energy storage

as

AM


Input: In this paper, a hybrid-AM system, combining low-cost fused filament fabrication (FFF) and direct ink writing (DIW) techniques, has been designed to fabricate supercapacitors (electro-chemical double layer capacitors, EDLCs) in a single, automated operation.

fused filament fabrication

FFF

DIW

fabricate

ink

designed

layer

capacitors


Input: The inherent flexibility of the AM process provided an opportunity to address restrictions in geometric form factor associated with conventional planar supercapacitor manufacturing approaches.

flexibility

AM process

manufacturing approaches

supercapacitor


Input: Functioning, ring-shaped EDLC devices were manufactured in a single, multi-material operation comprising symmetric activated carbon electrodes in a 1Μ potassium hydroxide (KOH) electrolyte hydrogel.

manufactured

multi-material

carbon

hydroxide

electrolyte


Input: The work aims to accelerate progress towards monolithic integration of energy storage devices in product manufacture, offering an alternative fabrication process for applications with irregular volume/shape and mass-customization requirements.

monolithic

energy storage

manufacture

fabrication


Input: A novel method to quantify the pore size distribution and porosity was proposed.

pore size

distribution

porosity


Input: New method exhibits high precision, information and repeatability but low cost.

precision

repeatability


Input: Electron beam melting (EBM) is a representative powder-bed fusion additive manufacturing technology, which is suitable for producing near-net-shape metallic components with complex geometries and near-full densities.

Electron beam melting

EBM

additive manufacturing

near-net-shape

fusion

complex geometries

metallic

components


Input: However, various types of pores are usually present in the additively manufactured components.

pores

additively manufactured


Input: These pores may affect mechanical properties, particularly the fatigue properties.

pores

fatigue

mechanical properties


Input: Therefore, inspection of size, quantity and distribution of pores is critical for the process control and assessment of additively manufactured components.

inspection

distribution

process control

pores

additively manufactured


Input: Here, we propose a method to quantify the pore size distribution and porosity of additively manufactured components by utilizing scanning optical microscopy.

pore size

distribution

porosity

additively manufactured

scanning optical microscopy


Input: The advantages and limitations of the developed method are discussed based on the comparison study between Archimedes method, conventional optical microscopy and x-ray computed tomography.

Archimedes method

optical microscopy

x-ray computed tomography


Input: This provides a new metrology for measurement of not only pores but also micro-cracks, which are the common defects in additively manufactured components.

metrology

micro-cracks

defects

measurement

pores

additively manufactured


Input: Four-dimensional (4D) printing has great potential for fabricating patient-specific, stimuli-responsive 3D structures for the medical sector.

3D structures

fabricating

medical


Input: Porous Shape memory polymers have high volumetric expansion and enhanced biological activity, which make them as ideal candidates for implant materials through minimally invasive surgical procedures.

Porous

polymers

as

implant


Input: In this paper, the porous SMPU was fabricated by combining extrusion, fused filament fabrication (FFF) and salt leaching.

porous

fabricated

extrusion

fused filament fabrication

FFF

leaching

salt


Input: The filament for FFF was produced by extruding the mixture of SMPU, NaCl, and Tungsten at the desired composition.

filament

NaCl

Tungsten

FFF

extruding

composition


Input: The 3D printed and salt leached porous SMPU was observed to have the porosity in the range of 32.7–36% and pore sizes of < 250 μm with anthe interconnected network.

3D printed

salt

porous

porosity

range

pore sizes


Input: The feasibility of combining fused filament fabrication and salt leaching technique was established for fabricating the radiopaque porous SMPU having the required characteristics for embolization, which can be explored by the Interventional Radiologist.

feasibility

fused filament fabrication

leaching

fabricating

salt

be

porous


Input: Limitations for the current clinical treatment strategies for breast reconstruction have prompted researchers and bioengineers to develop unique techniques based on tissue engineering and regenerative medicine (TE & RM) principles.

reconstruction

tissue engineering

medicine

TE


Input: Recently, scaffold-guided soft TE has emerged as a promising approach due to its potential to modulate the process of tissue regeneration.

TE

as

process

regeneration


Input: Herein, we utilized additive biomanufacturing (ABM) to develop an original design-based concept for scaffolds which can be applied in TE-based breast reconstruction procedures.

additive

be

scaffolds

reconstruction


Input: The scaffold design addresses biomechanical and biological requirements for medium to large-volume regeneration with the potential of customization.

scaffold

design

biomechanical

regeneration


Input: The model is composed of two independent structural components.

model

structural components


Input: The external structure provides biomechanical stability to minimize load transduction to the newly formed tissue while the internal structure provides a large pore and fully interconnected pore architecture to facilitate tissue regeneration.

structure

regeneration

biomechanical

architecture

internal structure

pore

pore


Input: A methodology was established to design, optimize and 3D print the external structure with customized biomechanical properties.

methodology

structure

design

3D print

biomechanical properties


Input: The internal structure was also designed and printed with a gradient of pore size and a channel structure to facilitate lipoaspirated fat delivery and entrapment.

internal structure

designed

pore size

channel


Input: A fused filament fabrication-based printing strategy was employed to print two structures as a monolithic breast implant.

fused

filament

as

print

monolithic

implant


Input: Numerical simulations of material deposition at corners in material extrusion AM.

Numerical simulations

material

deposition

material extrusion AM


Input: Toolpath smoothing and over-extrusion affect the corner rounding and swelling.

Toolpath

swelling


Input: An optimal amount of toolpath smoothing improves the quality of the corner.

toolpath

quality


Input: A uniform track width is obtained with a proportional extrusion rate.

extrusion rate


Input: The material deposition along a toolpath with a sharp corner is simulated with a computational fluid dynamics model.

material

deposition

toolpath

computational fluid dynamics


Input: We investigate the effects of smoothing the toolpath and material over-extrusion on the corner rounding and the corner swelling, for 90° and 30° turns.

toolpath

material

swelling


Input: The toolpath motion is controlled with trapezoidal velocity profiles constrained by a maximal acceleration.

toolpath

profiles


Input: The toolpath smoothing of the corner is parametrized by a blending acceleration factor.

toolpath

blending


Input: Analytical solutions for the deviation of the smoothed toolpath from the trajectory of the sharp corner, as well as the additional printing time required by the deceleration and acceleration phases in the vicinity of the turn are provided.

Analytical solutions

toolpath

as

as


Input: Moreover, several scenarios with different blending acceleration factors are simulated, for the cases of a constant extrusion rate and an extrusion rate proportional to the printing head speed.

blending

extrusion rate

extrusion rate

printing head


Input: The constant extrusion rate causes material over-extrusion during the deceleration and acceleration phases of the printing head.

extrusion rate

material

printing head


Input: However, the toolpath smoothing reduces the corner swelling.

toolpath

swelling


Input: A uniform road width is obtained with the proportional extrusion rate.

extrusion rate


Input: Proper support geometry design is critical for additive manufacturing (AM) techniques to be successful, particularly for material deposition AM techniques, such as fused deposition modeling (FDM).

support

geometry

deposition

deposition modeling

design

additive manufacturing

AM

AM techniques

FDM

be

material

as


Input: Many methods have been proposed for support geometry generation, mostly geared toward FDM and most often with the objective of minimizing support-material use and part-construction time.

support

geometry

FDM


Input: Here, two new support geometry algorithms are proposed, which are particularly suitable for weak support materials: the shell technique, whereby the primary support material would collapse under its own weight and thus a second support material is used to create a containment shell; the film technique, whereby a second support material is deposited as a thin film between the part and the primary support material.

support

geometry algorithms

support materials

support material

support material

support material

as

support material

shell

shell

weight


Input: The proposed techniques also facilitate support material removal, a laborious manual step for many AM processes.

support material

step

AM processes


Input: Both techniques are demonstrated through the construction of parts using an experimental large-scale 3D foam printer.

construction

experimental

printer


Input: Additive manufacturing (AM) is a promising approach for fabricating structures to serve as bone substitutes, or as biomaterial components in biphasic implants for repair of osteochondral defects.

Additive manufacturing

AM

fabricating

as

as

components

implants

defects


Input: In this study, the three dimensional printing (3DP) AM process was investigated to determine the effect of powder layer orientation on mechanical and structural properties of fabricated parts.

three dimensional printing

AM process

powder

layer

mechanical

properties

fabricated


Input: Five types of standard cylindrical parts were manufactured via AM with 0°, 30°, 45°, 60° and 90° stacking layer orientations relative to the vertical z-axis of the print bed, using amorphous calcium polyphosphate (CPP) powder of irregular particle shape, average aspect ratio ≈1.70 and particle size between 75 and 150 μm.

standard

cylindrical

manufactured

vertical

particle

particle

AM

print

layer

bed

calcium

powder

average aspect ratio


Input: It was concluded that layer orientation had an effect on porosity and compressive strength, based on induced powder particle orientation in the green part during powder layering.

layer

porosity

compressive strength

green part

powder particle

powder

orientation


Input: The resulting bulk porosity values ranged between 30.0 ± 2.4% and 38.2 ± 2.7%, while the compressive strength ranged between 13.50 ± 1.95 MPa and 45.13 ± 6.82 MPa.

bulk porosity

compressive strength

MPa

MPa


Input: The orientation with the highest compressive strength was 90°, while orientations with the weakest compressive strength were 0° and 45°.

orientation

orientations

compressive strength

compressive strength


Input: The stacking layer orientation which results in the highest strength performance along a preferred loading orientation can be implemented to further optimize mechanical strength of constructs along the maximum loading direction.

layer

strength

mechanical strength

performance

orientation

be


Input: Recent efforts in the bone and tissue engineering field have been made to create resorbable bone scaffolds that mimic the structure and function of natural bone.

bone

bone scaffolds

bone

tissue engineering

structure

mimic


Input: While enhancing mechanical strength through increased ceramics loading has been shown for sintered parts, few studies have reported that the crosslinked polymer provides strength for the composite parts without post processing.

mechanical strength

strength

ceramics

polymer

composite

sintered

post processing


Input: The objective of this study is to assess the effect of amylose content on the mechanical and physical properties of starch-hydroxyapatite (HA) composite scaffolds for bone and tissue engineering applications.

mechanical

physical properties

composite

bone

tissue engineering


Input: Starch-HA composite scaffolds utilizing corn, potato, and cassava sources of gelatinized starch were fabricated through the utilization of a self-designed and built solid freeform fabricator (SFF).

composite

starch

fabricated

freeform


Input: It was hypothesized that the mechanical strength of the starch-HA scaffolds would increase with increasing amylose content based on the botanical source and weight percentage added.

mechanical strength

scaffolds

source

weight


Input: Overall, compressive strengths of scaffolds were achieved up to 12.49 ± 0.22 MPa, through the implementation of 5.46 wt% corn starch with a total amylose content of 1.37%.

compressive strengths

scaffolds

MPa

starch


Input: The authors propose a reinforcement mechanism through a matrix of gelled starch particles and interlocking of hydroxyl-rich amylose with hydroxyapatite through hydrogen bonding.

reinforcement

mechanism

particles

hydrogen bonding

starch

hydroxyapatite


Input: XRD, FTIR, and FESEM were utilized to further characterize these scaffold structures, ultimately elucidating amylose as a biologically relevant reinforcement phase of resorbable bone scaffolds.

XRD

FTIR

FESEM

scaffold

as

reinforcement

phase

bone scaffolds


Input: Significant efforts have been made to treat bone disorders through the development of composite scaffolds utilizing calcium phosphate (CaP) using additive manufacturing techniques.

bone

composite

calcium phosphate

additive manufacturing


Input: However, the incorporation of natural polymers with CaP during 3D printing is difficult and remains a formidable challenge in bone and tissue engineering applications.

polymers

3D printing

bone

tissue engineering


Input: The objective of this study is to understand the use of a natural polymer binder system in ceramic composite scaffolds using a ceramic slurry-based solid freeform fabricator (SFF).

polymer binder

ceramic

ceramic composite

freeform


Input: This was achieved through the utilization of naturally sourced gelatinized starch with hydroxyapatite (HA) ceramic in order to obtain high mechanical strength and enhanced biological properties of the green part without the need for cross-linking or post processing.

starch

hydroxyapatite

ceramic

mechanical strength

green part

properties

cross-linking

post processing


Input: The parametric effects of solids loading, polycaprolactone (PCL) polymer addition, and designed porosity on starch-HA composite scaffolds were measured via mechanical strength, microstructure, and in vitro biocompatibility utilizing human osteoblast cells.

PCL

polymer

composite

designed

mechanical strength

biocompatibility

microstructure

osteoblast cells


Input: It was hypothesized that starch incorporation would improve the mechanical strength of the scaffolds and increase proliferation of osteoblast cells in vitro.

starch

osteoblast cells

mechanical strength

scaffolds


Input: Starch loading was shown to improve mechanical strength from 4.07 ± 0.66 MPa to 10.35 ± 1.10 MPa, more closely resembling the mechanical strength of cancellous bone.

Starch

cancellous bone

mechanical strength

mechanical strength

MPa

MPa


Input: Based on these results, a reinforcing mechanism of gelatinized starch based on interparticle and apatite crystal interlocking is proposed.

mechanism

starch

apatite


Input: Morphological characterization utilizing FESEM and MTT cell viability assay showed enhanced osteoblast cell proliferation in the presence of starch and PCL.

Morphological characterization

FESEM

cell viability

osteoblast cell

starch

PCL


Input: Overall, the utilization of starch as a natural binder system in SFF scaffolds was found to improve both compressive strength and in vitro biocompatibility.

starch

as

binder

scaffolds

compressive strength

biocompatibility


Input: a) Ceramic slurry preparation of starch and hydroxyapaitite (HA) utilized for fabrication of bone scaffolds without the need for post processing.

Ceramic

starch

bone scaffolds

fabrication

post processing


Input: b) Schematic of Solid Freeform Fabricator.

b

Freeform


Input: c) Representation of scaffold model utilizing solid works file and CURA program and final scaffold prints d) in vitro cell work regarding the proliferation of osteoblast cells utilizing starch based composite HA scaffolds, ultimately acquiring sufficient mechanical integrity and enhanced biactivity to be utilized in bone repair.Download: Download high-res image (217 Bonding in additive manufacturing (AM) remains a key challenge in improving part properties.

c

composite

be

scaffold model

high-res image

Bonding

properties

file

scaffold

scaffolds

cell

osteoblast cells

starch

bone

mechanical integrity

additive manufacturing

AM


Input: For thermally driven AM methods, such as material extrusion AM (MatEx), temperature governs bonding.

AM

extrusion AM

as

temperature

bonding


Input: Experimental measurements of temperature are limited in their ability to probe many points in space and time during a process without disturbing the temperature profiles being measured.

Experimental

process

temperature

temperature

probe

profiles


Input: These limitations may be overcome with computational methods; however, computing power considerations confined simulations to one or two dimensions until recently.

be

computational methods

simulations

power

dimensions


Input: Additionally, most existing models have had only limited ability to modify geometry or process parameters.

geometry

process parameters


Input: In this work, an adaptable FEA model capable of simulating heat transfer in 3D and at sufficiently small time scales to capture the rapid cooling in AM is presented.

model

heat transfer

time scales

cooling

AM


Input: Cooling trends from simulation are shown to be in agreement with experimental data.

Cooling

simulation

be

experimental data


Input: Temperature profiles are collapsed to equivalent time at a reference temperature and predict little variation in bonding along the z-axis of a part or with changes in print speed.

Temperature

temperature

profiles

variation

bonding

z-axis

print


Input: A previously unreported peak in cooling rates for print speeds between 10 and 30 mm/s is shown.

cooling rates

print


Input: Uniformity in equivalent time at Tg suggests weld strength will not vary with print speed; however, high cooling rates for common print speeds may lead to greater residual stresses and reduced mechanical properties.

Tg

weld strength

residual stresses

print

print

cooling rates

lead

mechanical properties


Input: Demonstrates PBF printing of high-performance polymer, PPS, on standard printer.

PBF

polymer

standard

printer


Input: Evaluates the universality of print parameter selection methods for non-polyamides.

print

parameter


Input: XY plane printed dogbones show failure at 61.8 ± 4.0 MPa and 3.27 ± 0.22%.

failure

MPa


Input: In this paper, the authors present evidence of printing poly (phenylene sulfide) (PPS), a high-performance polymer, via powder bed fusion (PBF) using a bed temperature of 230 °C, which is significantly below both its observed melting temperature (Tm ˜ 285 °C) and its observed onset temperature of crystallization (Tc ˜ 255 °C).

polymer

powder bed fusion

PBF

bed

melting temperature

temperature

crystallization


Input: This contradicts existing material screening guidelines for PBF, which suggest maintaining bed temperature above the observed onset of crystallization.

material

PBF

bed

crystallization


Input: Existing methods for theoretically determining processing bounds were used to predict a range of energy densities at which PPS can be printed.

range

energy densities

be


Input: One combination of process parameter values was selected based on machine constraints imposed by typical PBF machines not designed to print high-temperature polymers and used to fabricate multilayer, complex parts.

process parameter

machine

PBF machines

designed

print

fabricate

polymers


Input: The presented process parameters result in final part density upwards of 1.18 g/cm3 and ultimate tensile strength and elongation of 62 MPa and 3.3%, respectively.

process parameters

MPa

density

ultimate tensile strength

elongation


Input: Hypotheses on the generalizability of low-temperature PBF printing of high-performance polymers, and steps towards updating materials and process parameter selection guidelines for PBF, are also presented.

PBF

PBF

polymers

materials

process parameter


Input: We demonstrate a novel Fused Filament Fabrication (FFF) nozzle design to enable measurements of in-situ conditions inside FFF nozzles, which is critical to ensuring that the polymer extrudate is flowing at appropriate temperature and flow rate during the part build process.

Fused Filament Fabrication

FFF

FFF

nozzle

design

in-situ

polymer extrudate

temperature

flow rate

build


Input: Testing was performed with ABS filament using a modified Monoprice Maker Select 3D printer.

Testing

ABS

3D printer


Input: In-situ measurements using the printer’ s default temperature control settings showed an 11 °C decrease in temperature and significant fluctuation in pressure during printing as well as fluctuations while idle of ± 2 °C and ±14 kPa.

In-situ

pressure

printer

s

as

as

temperature

temperature


Input: These deviations were eliminated at lower flow rates with a properly calibrated proportional–integral–derivative (PID) system.

flow rates

calibrated


Input: At the highest tested flow rates, decreases in melt temperature as high as 6.5 °C were observed, even with a properly calibrated PID, providing critical insight into the significance of flow rate and PID calibration on actual polymer melt temperature inside the FFF nozzle.

flow rates

flow rate

melt

calibrated

calibration

as

as

polymer melt

FFF


Input: Pressure readings ranging from 140 to 6900 kPa were measured over a range of filament feed rates and corresponding extrusion flow rates.

Pressure

range

feed

filament

extrusion


Input: In-situ pressure measurements were higher than theoretical predictions using a power-law fluid model, suggesting that the assumptions used for theoretical calculations may not be completely capturing the dynamics in the FFF liquefier.

In-situ

theoretical predictions

theoretical

fluid

be

FFF


Input: Our nozzle prototype succeeded in measuring the internal conditions of FFF nozzles, thereby providing a number of important insights into the printing process which are vital for monitoring and improving FFF printed parts.

nozzle

FFF

printing process

FFF


Input: Increasing void size in printed objects through FFF negatively affects strength Novel method of FFF proposed to reduce the void size Novel method reduces cross-sectional void surface area by 18.0% Novel method improves density by 6.5% per mm increase in nozzle size Novel method improves max.

void

void

void

FFF

FFF

mm

strength

density

surface area

nozzle


Input: shear stress by 7.2% per mm increase in nozzle size Additive manufacturing techniques, such as Fused Filament Fabrication (FFF), are rapidly revolutionising the manufacturing and mining sectors.

shear stress

mm

Additive manufacturing

Fabrication

FFF

manufacturing

nozzle

as

Filament


Input: Firstly, an alternative method of filament positioning in material extrusion is proposed, referred to as the ‘offset method’, which aims to reduce the volume of empty cavities between deposited material.

filament

as

material

material extrusion

offset

volume


Input: Then the shear properties, density properties, and cross-sectional void surface area are compared to structures printed using the aligned printing method.

shear properties

density

void

surface area


Input: Experimental results on solid printed (no infill) samples, through four different- sized nozzles, have shown the newly proposed method produces a 6.5% increase in density and a 7.2% improvement in maximum in-plane shear stress per millimetre increase in nozzle size, compared with the aligned method of FFF.

Experimental

samples

infill

nozzles

nozzle

density

shear stress

FFF


Input: The offset method was found to produce a material with increased interlayer contact, compared to the aligned method, which results in a higher fictitious shear stress modulus.

offset

material

contact

shear stress


Input: The effect of the increased interlayer contact on the fictitious shear modulus and real shear stress was investigated using a FEM analysis of the unit cells.

contact

shear modulus

shear stress

FEM

unit cells


Input: In short, using the same feedstock material, the offset method produces a stiffer material with a higher fictitious shear strength than the aligned method of FFF printing.

feedstock material

material

offset

shear strength

FFF


Input: This study focuses on the characterization of additive manufacturing technology based on composite filament fabrication (CFF).

additive manufacturing

fabrication

composite


Input: CFF utilizes a similar method of layer by layer printing as fused filament fabrication but is also capable of reinforcing parts with layers of various continuous fibers into a polymer matrix.

layer by layer

as

filament

continuous fibers

polymer

fabrication


Input: Due to the orthotropic characteristics of additive manufacturing based on fused filament fabrication, 3D printed parts may present different mechanical behavior under different orientations of stress.

orthotropic

additive manufacturing

fused filament fabrication

3D printed parts

mechanical

orientations

stress


Input: Furthermore, technologies such as CFF allow a range of configurations to fabricate and reinforce the parts.

technologies

as

range

fabricate


Input: In this study, mechanical characterization of polyamide 6 (PA6) reinforced with carbon fiber was conducted by design of experiment as a statistical method, to investigate the effect of reinforcement pattern, reinforcement distribution, print orientation and percentage of fiber on compressive and flexural mechanical properties.

mechanical

polyamide

carbon fiber

as

fiber

reinforced

design of experiment

statistical method

pattern

distribution

orientation

mechanical properties

reinforcement

reinforcement

print


Input: CFF technology 3D print stronger parts than conventional additive manufacturing technologies.

CFF technology

3D print

additive manufacturing


Input: Maximized compressive response was achieved with a 0.2444 Carbon Fiber volume ratio, concentric and equidistant reinforcement configuration, resulting in a compressive modulus of 2.102 GPa and a stress at proportional limit of 53.3 MPa.

Carbon Fiber

reinforcement

proportional limit

configuration

MPa

GPa

stress


Input: Maximized flexural response was achieved with 0.4893 Carbon Fiber volume ratio, concentric reinforcement and perpendicular to the applied force, resulting in a flexural modulus of 14.17 GPa and a proportional limit of 231.1 MPa.

Carbon Fiber

reinforcement

proportional limit

force

MPa

GPa


Input: This study presents development of a test method for characterization of interlayer, mode-I fracture toughness of fused filament fabrication (FFF) materials using a modified double cantilever beam (DCB) test.

fracture

materials

fused filament fabrication

FFF

cantilever beam


Input: This test consists of DCB specimen fabricated from using unidirectional FFF layers, an 8 μm Kapton starter crack inserted in the midplane during the printing process, and reinforcing glass/epoxy doublers to prevent DCB arm failure during loading.

fabricated

unidirectional

midplane

failure

FFF

printing process


Input: DCB specimens are manufactured with a commercially available 3D printer using unreinforced Acrylonitrile Butadiene Styrene (ABS) and chopped carbon-fiber-reinforced ABS (CF-ABS) filaments.

manufactured

3D printer

Acrylonitrile Butadiene Styrene

ABS

ABS

filaments


Input: To examine the effect of the FFF printing process on fracture toughness, additional ABS and CF-ABS specimens are hot-press molded using the filament material, and tested with the single end notch bend (SENB) specimen configuration.

FFF

process

fracture

configuration

ABS

filament

notch


Input: The fracture toughness data from DCB and SENB tests reveal that the FFF process significantly lowers the mode-I fracture toughness of ABS and CF-ABS.

fracture

data

fracture

FFF

ABS


Input: For both materials, in situ thermal imaging and post-mortem fractography shows, respectively, rapid cool-down of the rasters during filament deposition and presence of voids between adjacent raster roads; both of which serve to reduce fracture toughness.

materials

in situ

deposition

voids

fracture

imaging

fractography

filament


Input: For CF-ABS specimens, fracture toughness is further reduced by inclusion of poorly wetted chopped carbon fibers.

fracture

inclusion

carbon fibers


Input: Although this study did not attempt to optimize the fracture performance of FFF specimens, the results demonstrate that the proposed methodology is suitable for design and optimization of FFF processes for improved interlayer fracture performance.

fracture

methodology

optimization

fracture

FFF

FFF

design


Input: Polyimides are a group of high performance thermal stable dielectric materials used in diverse applications.

Polyimides

performance

dielectric


Input: In this article, we synthesized and developed a high-performance polyimide precursor ink for a Material Jetting (MJ) process.

precursor ink

Material Jetting

MJ

process


Input: The proposed ink formulation was shown to form a uniform and dense polyimide film through reactive MJ utilising real-time thermo-imidisation process.

ink

MJ

process


Input: By means of selectively depositing 4 μm thick patches at the cross-over points of two circuit patterns, a traditional double-sided printed circuit board (PCB) can be printed on one side, providing the user with higher design freedom to achieve a more compact high performance PCB structure.

printed circuit board

be

design freedom

performance

structure

compact


Input: This study presents development of a test method for characterization of interlayer, mode-I fracture toughness of fused filament fabrication (FFF) materials using a modified double cantilever beam (DCB) test.

fracture

materials

fused filament fabrication

FFF

cantilever beam


Input: This test consists of DCB specimen fabricated from using unidirectional FFF layers, an 8 μm Kapton starter crack inserted in the midplane during the printing process, and reinforcing glass/epoxy doublers to prevent DCB arm failure during loading.

fabricated

unidirectional

midplane

failure

FFF

printing process


Input: DCB specimens are manufactured with a commercially available 3D printer using unreinforced Acrylonitrile Butadiene Styrene (ABS) and chopped carbon-fiber-reinforced ABS (CF-ABS) filaments.

manufactured

3D printer

Acrylonitrile Butadiene Styrene

ABS

ABS

filaments


Input: To examine the effect of the FFF printing process on fracture toughness, additional ABS and CF-ABS specimens are hot-press molded using the filament material, and tested with the single end notch bend (SENB) specimen configuration.

FFF

process

fracture

configuration

ABS

filament

notch


Input: The fracture toughness data from DCB and SENB tests reveal that the FFF process significantly lowers the mode-I fracture toughness of ABS and CF-ABS.

fracture

data

fracture

FFF

ABS


Input: For both materials, in situ thermal imaging and post-mortem fractography shows, respectively, rapid cool-down of the rasters during filament deposition and presence of voids between adjacent raster roads; both of which serve to reduce fracture toughness.

materials

in situ

deposition

voids

fracture

imaging

fractography

filament


Input: For CF-ABS specimens, fracture toughness is further reduced by inclusion of poorly wetted chopped carbon fibers.

fracture

inclusion

carbon fibers


Input: Although this study did not attempt to optimize the fracture performance of FFF specimens, the results demonstrate that the proposed methodology is suitable for design and optimization of FFF processes for improved interlayer fracture performance.

fracture

methodology

optimization

fracture

FFF

FFF

design


Input: This paper presents an end-to-end design process for compliance minimization-based topological optimization of cellular structures through to the realization of a final printed product.

design process

topological optimization

cellular structures


Input: Homogenization is used to derive properties representative of these structures through direct numerical simulation of unit cell models.

Homogenization

properties

unit cell

numerical simulation


Input: The resulting homogenized properties are then used assuming uniform distribution of the cellular structure to compute the macroscale structure.

homogenized

distribution

macroscale

cellular structure


Input: Results are presented that illustrate the fine-scale stresses developed in the macroscale optimized part as well as the effect that fine-scale structure has on the optimized topology.

macroscale

structure

topology

as

as


Input: Quite fine cellular structures are shown to be possible using this method.

cellular structures

be


Input: Fused Filament Fabrication (FFF) is the most widely available Additive Manufacturing technology.

Fused Filament Fabrication

FFF

Additive Manufacturing


Input: Offering the possibility of producing complex geometries in a compressed product development cycle and in a plethora of materials, it comes as no surprise that FFF is attractive to multiple industries, including the automotive and aerospace segments.

complex geometries

product development

materials

as

FFF

industries

automotive

aerospace


Input: However, the high anisotropy of parts developed through this technique implies that failure prediction is extremely difficult -a requirement that must be satisfied to guarantee the safety of the final user.

anisotropy

failure

safety

be


Input: This work applies a criterion that incorporates stress interactions to define a 3D failure envelope that could prove an invaluable tool in formalizing the embrace of FFF in industry.

stress

tool

FFF

industry


Input: Tensile, compressive and torsion tests were executed on coupons developed in a traditional FFF printer, as well as a customized, 6-axis robotic printer necessary to produce specimens in out of ordinary orientations.

Tensile

torsion tests

FFF

as

as

printer

orientations


Input: These tests were used to calculate the parameters of the mathematical function that describe the failure envelope.

parameters

mathematical

failure


Input: Mechanical tests clearly showed significant difference between tensile, compressive and shear strengths.

Mechanical tests

tensile

shear strengths


Input: The calculated envelope shows strong interactions between axial loads, and a considerable interaction between shear stresses and loads applied in directions parallel and perpendicular to the beads.

shear stresses

beads


Input: A new class of high-performance resins are available for additive manufacturing with the introduction of Digital Light Synthesis (DLS) technology.

resins

additive manufacturing

Digital Light Synthesis

DLS

technology


Input: In combination with Continuous Liquid Interface Production (CLIP), DLS uses ultraviolet light and oxygen to continuously grow objects from a pool of resin instead of printing them layer-by-layer, subsequently increasing the printing speed and the mechanical performance.

Continuous Liquid Interface Production

CLIP

DLS

ultraviolet light

layer-by-layer

oxygen

resin

printing speed

mechanical


Input: For many DLS resin systems, a secondary thermal curing step is required in order to reach the final material properties after printing.

DLS

curing

material properties


Input: This step is a major limiting factor in the production time of the DLS process, as materials may require several hours of thermal post curing.

step

production

DLS

curing

as


Input: The aim of this study is to optimize this secondary curing cycle for the epoxy-based resin EPX 82 by reducing the thermal curing time while avoiding a negative influence on the final mechanical properties.

curing

resin

curing time

mechanical properties


Input: Differential scanning calorimetry (DSC) was used with different heating rates and a chemical reaction model was developed.

scanning

chemical reaction

DSC

heating


Input: The Di Benedetto relationship was used to include diffusion control for high degrees of cure.

diffusion

cure


Input: Powder Bed Fusion (PBF) is a range of advanced manufacturing technologies that can fabricate three-dimensional assets directly from CAD data, on a successive layer-by-layer strategy by using thermal energy, typically from a laser source, to irradiate and fuse particles within a powder bed.The aim of this paper was to investigate the application of this advanced manufacturing technique to process ceramic multicomponent materials into 3D layered structures.

Powder Bed Fusion

PBF

manufacturing technologies

fabricate

fuse

manufacturing

range

CAD

layer-by-layer

thermal energy

process

materials

laser source

powder

ceramic


Input: The materials used matched those found on the Lunar and Martian surfaces.

materials

surfaces


Input: The indigenous extra-terrestrial Lunar and Martian materials could potentially be used for manufacturing physical assets onsite (i.e., off-world) on future planetary exploration missions and could cover a range of potential applications including: infrastructure, radiation shielding, thermal storage, etc.Two different simulants of the mineralogical and basic properties of Lunar and Martian indigenous materials were used for the purpose of this study and processed with commercially available laser additive manufacturing equipment.

materials

properties

materials

processed

be

manufacturing

radiation

laser additive manufacturing

range

equipment


Input: The results of the laser processing were investigated and quantified through mechanical hardness testing, optical and scanning electron microscopy, X-ray fluorescence spectroscopy, thermo-gravimetric analysis, spectrometry, and finally X-ray diffraction.The research resulted in the identification of a range of process parameters that resulted in the successful manufacture of three-dimensional components from Lunar and Martian ceramic multicomponent simulant materials.

laser processing

research

process parameters

manufacture

three-dimensional

materials

mechanical

hardness

optical

scanning electron microscopy

X-ray

fluorescence

X-ray

range

components

ceramic


Input: The feasibility of using thermal based additive manufacturing with multi-component ceramic materials has therefore been established, which represents a potential solution to off-world bulk structure manufacture for future human space exploration.

feasibility

solution

structure manufacture

additive manufacturing

ceramic materials


Input: This study investigates the moisture absorption characteristics of the ULTEM® 9085 filament and how the uptake concentration affects the quality of material extrusion manufactured 3-D parts.

investigates

absorption

quality

manufactured 3-D

filament

material extrusion


Input: The rate of transport was modeled by Fickian diffusion and diffusion coefficients were obtained for various exposure conditions.

transport

diffusion

diffusion

exposure


Input: Moduli, strain to failure and ultimate strength were evaluated in the XY (flat horizontal) and ZX (vertical) direction relative to the build plate orientation.

strain

ultimate strength

failure

vertical

build plate


Input: Image analyses of cross-sections as well as their corresponding fracture surfaces were evaluated for consolidation, porosity distribution and failure behavior.

Image analyses

cross-sections

fracture

consolidation

distribution

failure

as

as

porosity


Input: Mechanical test data showed a significant decrease in tensile strength (> 60%) and failure strain (> 50%) over the range of filament moisture levels investigated.

Mechanical test

data

failure

tensile strength

range

filament


Input: A decrease in failure strain of 41% was observed with moisture levels as low as 0.16%.

failure

as

as


Input: This degradation was especially sensitive in parts printed in the vertical direction, which resulted in an ultimate failure strain of only 1%.

degradation

vertical

failure


Input: The changes in mechanical performance are believed to be due to a combination of entrapped volatiles resulting in increased porosity at higher moisture levels as well as moisture induced pseudo-crosslinking at lower concentrations.

mechanical

be

as

as

porosity


Input: Optical micrographs showed that specimens with 0.16% moisture or greater were filled with observable porosity and increased surface roughness.

Optical

porosity

surface roughness


Input: The rheological behavior of extruded material indicated plasticization as evidenced by melt flow index measurements and changes in the flow characteristics of moisture-exposed extrudate.

rheological

extruded

as

extrudate

melt flow index


Input: DMA data show a distinct decrease in Tg with increased moisture content, which is consistent with plasticization.

DMA data

Tg


Input: The absorption characteristics at room temperature lab conditions indicate that the material will reach an unacceptable level within one hour of room-temperature exposure.

absorption

exposure

temperature

material


Input: This investigation emphasized the need for awareness of the moisture sensitivities of ULTEM® 9085 when manufacturing high-quality material extrusion processed structures.

sensitivities

manufacturing

material extrusion


Input: Stereolithography (SL) is an additive manufacturing technique that uses light to cure liquid resins into thin layers and fabricate 3-dimensional objects layer by layer.

Stereolithography

SL

additive manufacturing

fabricate

cure

layer by layer

resins


Input: SL is of high interest for small-volume manufacturing and rapid prototyping because of its ability to relatively quickly create objects with intricate 100 μm or smaller features.

SL

manufacturing

rapid prototyping


Input: However, widespread adoption of SL faces a number of obstacles including unsuitable thermomechanical properties, anisotropic properties, and limited resolution and fidelity.

SL

thermomechanical properties

anisotropic

resolution


Input: In this work, we incorporate a reversible addition-fragmentation chain transfer (RAFT) agent into a glassy acrylate formulation to modify mechanical properties and improve resolution of objects printed using digital light processing (DLP) SL.

RAFT

mechanical properties

resolution

digital light processing

DLP

SL


Input: Incorporating a small amount of a trithiocarbonate RAFT agent into the formulation leads to increased elongation and toughness accompanied by a small decrease in tensile modulus.

RAFT

elongation

toughness

tensile


Input: To determine anisotropic properties of DLP SL, samples were printed in “horizontal” or “vertical” directions, where the long axis of the sample was printed in the x-axis or z-axis, respectively.

anisotropic

DLP

samples

vertical

sample

z-axis


Input: RAFT samples printed in a vertical orientation exhibit a higher modulus than non-RAFT controls prior to post-cure in addition to a similar modulus with increased toughness upon UV post-cure due to the living/controlled nature of RAFT polymerization.

RAFT

RAFT

vertical orientation

UV

toughness

polymerization


Input: Furthermore, incorporating a RAFT agent into the formulation allows significantly higher fidelity printing of a broad range of positive and negative features as small as 100 μm.

RAFT

range

as

as


Input: The RAFT formulation allows objects to be printed with significantly better fidelity than non-RAFT formulations, even when a radical scavenger is incorporated to mimic reaction rates observed from the RAFT formulation.

RAFT

mimic

RAFT

be


Input: Additionally, the RAFT agent significantly increases the critical energy parameter determined from the SL working curve, indicating an increase in gel point conversion.

RAFT

parameter

SL

gel point


Input: This work demonstrates the benefits of using controlled/living polymerization in a highly cross-linked acrylate system to improve toughness, modify anisotropic properties, and print high-fidelity features with enhanced properties in 3D printed materials.

polymerization

print

3D printed

toughness

anisotropic

high-fidelity

properties


Input: Support structures and materials are indispensable components in many Additive Manufacturing (AM) systems in order to fabricate complex 3D structures.

Support structures

materials

3D structures

components

Additive Manufacturing

AM

fabricate


Input: For inkjet-based AM techniques (known as Material Jetting), there is a paucity of studies on specific inks for fabricating such support structures.

AM techniques

Jetting

fabricating

as

support structures


Input: This limits the potential of fabricating complex 3D objects containing overhanging structures.

limits

overhanging structures

fabricating

3D objects


Input: In this paper, we investigate the use of Tripropylene Glycol Diacrylated (TPGDA) to prepare a thermally stable ink with reliable printability to produce removable support structures in an experimental Material Jetting system.

ink

printability

support structures

experimental

Jetting


Input: The addition of TGME to the TPGDA was found to considerably reduce the modulus of the photocured structure from 575 MPa down to 27 MPa by forming micro-pores in the cured structure.

structure

MPa

MPa

forming

cured


Input: The cured support structure was shown to be easily removed following the fabrication process.

cured

fabrication

structure

be


Input: During TG-IR tests the T5% temperature of the support structure was above 150 °C whilst the majority of decomposition happened around 400 °C.

temperature

support structure

decomposition


Input: Specimens containing overhanging structures (gate-like structure, propeller structure) were successfully manufactured to highlight the viability of the ink as a support material.

overhanging structures

structure

structure

manufactured

ink

as

support material


Input: The potential of topology optimization to amplify the benefits of additive manufacturing (AM), by fully exploiting the vast design space that AM allows, is widely recognized.

topology optimization

additive manufacturing

AM

AM

design space


Input: However, existing topology optimization approaches do not consider AM-specific limitations during the design process, resulting in designs that are not self-supporting.

topology optimization

designs

self-supporting

design process


Input: This leads to additional effort and costs in post-processing and use of sacrificial support structures.

post-processing

support structures


Input: To overcome this difficulty, this paper presents a topology optimization formulation that includes a simplified AM fabrication model implemented as a layerwise filtering procedure.

topology optimization

AM

model

as


Input: Unprintable geometries are effectively excluded from the design space, resulting in fully self-supporting optimized designs.

geometries

design space

self-supporting

designs


Input: The procedure is demonstrated on numerical examples involving compliance minimization, eigenfrequency maximization and compliant mechanism design.

compliant mechanism


Input: Despite the applied restrictions, in suitable orientations fully printable AM-restrained designs matched the performance of reference designs obtained by conventional topology optimization.

orientations

performance

designs

designs

topology optimization


Input: To enable the advancement of large-scale additive manufacturing processes, it is necessary to establish and standardize methodologies to characterize the mechanical properties of printed test coupons.

additive manufacturing processes

mechanical properties


Input: Due to the large size of the print beads, conventional test standards are inadequate.

print

beads

standards


Input: The focus of this study was to determine the feasibility of using Digital image correlation (DIC) technology as a key enabler for robust data collection of strain measurements of large 3D printed parts.

feasibility

Digital image correlation

DIC

technology

data

as

strain

3D printed parts


Input: ) glass filled ABS test coupons for adequate contrast.

glass

ABS


Input: Through this technique, Poisson's ratio and elastic modulus were measured and stress strain curves were generated.

elastic modulus

stress strain curves


Input: The data produced by DIC correlated well with failure analysis performed on spent test coupons.

data

DIC correlated

failure


Input: Additionally, fracture surface analysis of the specimens revealed poor adhesion among the ABS matrix and glass fibers.

fracture

adhesion

ABS matrix

glass fibers


Input: This matrix/fiber debonding demonstrated the need for improved printing parameters to maximize tensile strength.

parameters

tensile strength


Input: Finally, critical length analysis of the fibers revealed them to be dimensionally inadequate.

fibers

be


Input: In this work, acrylonitrile butadiene styrene (ABS) was reinforced with a thermotropic liquid crystalline polymer (TLCP) for use in Fused Filament Fabrication (FFF).

acrylonitrile butadiene styrene

ABS

thermotropic liquid crystalline polymer

reinforced

Fused Filament Fabrication

FFF


Input: As ABS and the selected TLCP do not exhibit overlapping processing temperatures, the composite filaments were generated using a dual extrusion technology which allows processing of such matrix-TLCP combinations.

As

ABS

composite

temperatures

extrusion


Input: The 40.0 wt.% TLCP/ABS filaments exhibited a tensile strength and modulus of 169.2 ± 4.0 MPa and 39.9 ± 3.7 GPa, respectively, due to a nearly continuous reinforcement of the filament.

filaments

filament

tensile strength

GPa

MPa

reinforcement


Input: The postprocessing of the filaments in FFF was carried out below the melting temperature of the TLCP, which allowed the printer to take sharp turns despite having nearly continuous reinforcement.

postprocessing

filaments

FFF

melting temperature

reinforcement

printer


Input: On printing with the 40.0 wt.% TLCP/ABS filaments, the tensile strength and modulus in the print direction were 74.9 ± 2.4 MPa and 16.5 ± 0.8 GPa, respectively.

filaments

tensile strength

GPa

print

MPa


Input: The compression molded specimens exhibited a tensile strength and modulus of 79.6 ± 4.4 MPa and 12.3 ± 1.2 GPa, respectively, whereas the injection molded specimens exhibited 51.3 ± 3.0 MPa and 4.5 ± 0.1 GPa, respectively.

compression

tensile strength

GPa

GPa

MPa

MPa


Input: Moisture absorption degrades the mechanical properties of polymeric parts that are 3D-printed by fused filament fabrication (FFF).

absorption

mechanical properties

fused filament fabrication

FFF


Input: This limitation is particularly significant for short fiber-reinforced polymers because the mechanical enhancement obtained by the fiber reinforcement can be compromised by the plasticizing effect introduced by water absorption.

polymers

be

mechanical

fiber reinforcement

absorption


Input: Therefore, the present work investigates the effects of two different coatings, a UV cured acrylate resin and an acrylic varnish, on the moisture absorption of FFF 3D-printed samples consisting of polyamide reinforced by short carbon fibers.

investigates

UV cured

absorption

coatings

resin

acrylic

polyamide

short carbon fibers

FFF 3D-printed


Input: The coating effects were evaluated by conducting tensile tests to compare the Young’ s modulus, yield stress, and ultimate stress of the coated and uncoated specimens.

coating

coated

tensile tests

s

yield stress

stress


Input: The results demonstrated a significant reduction of CI and OP with both the acrylic and UV resin coatings, as well as considerable enhancements of these samples’ mechanical properties.

reduction

UV

samples

mechanical properties

CI

acrylic

resin coatings

as

as


Input: Stress-strain curves evidenced a strain reduction after water immersion, which can be ascribed to a greater stability against different moisture conditions.

strain

stability

reduction

be


Input: These findings indicate the significant potential of the proposed coating processes to extend the use of FFF 3D-printed composite materials to a broader range of applications.

coating

FFF 3D-printed

composite materials

range


Input: In this paper, the effects of part build directions or raster orientations have been studied on the strain-life fatigue parameters of a wide range of 3D printed plastic materials.

build directions

raster orientations

range

fatigue

3D printed

materials


Input: These materials have been manufactured through Fused Filament Fabrication (FFF), also known under its trademarked name Fused Deposition Modeling (FDM).

materials

manufactured

Fused Filament Fabrication

FFF

Fused Deposition Modeling

FDM


Input: To do so, precise analyses of fatigue data with the Ramberg-Osgood form of stress-strain curves were utilized through a strain-based approach to fatigue.

fatigue

fatigue

data


Input: Materials considered in this study were Ultem 9085, Polycarbonate (PC), and Polylactic Acid (PLA).

Materials

Polycarbonate

PC

Polylactic Acid

PLA


Input: Additive manufactured plastic parts that are FDM-processed exhibited large anisotropy of strain-life fatigue parameters.

Additive manufactured

anisotropy

fatigue


Input: Hence, the upper and lower bounds for fatigue life prediction were introduced based on the strongest and weakest part build directions or raster orientations of 3D printed materials.

fatigue life

build directions

raster orientations

3D printed


Input: For all materials studied in the present paper, fill densities, which seem to have significant impact on fatigue strength of 3D printed parts, have been selected based on the maximum fatigue strength of each part.

materials

impact

fatigue strength

fatigue strength

3D printed parts


Input: Results showed that, in some build orientations, the transition fatigue life does not exist.

build orientations

transition

fatigue life


Input: In other orientations, in which the plastic strain components are high enough, transition fatigue lives vary roughly between 20–400 cycles.

orientations

transition

plastic

components

fatigue lives


Input: This means that if the part design in very low cycle fatigue regime is of interest, plastic strains and more complicated plasticity analysis are needed.

design

fatigue

plasticity

plastic


Input: Results show that the load ratio has no major impact on the fatigue parameters of 3D printed PC parts.

impact

fatigue

3D printed


Input: In addition, changing in the loading type from tensile fatigue to rotating bending fatigue can significantly impact the fatigue strength coefficient of 3D printed PLA specimens however, it does not noticeably alter the fatigue strength exponents.

tensile fatigue

fatigue strength

fatigue strength

bending

3D printed

impact


Input: Material extrusion additive manufacturing utilizes a thermoplastic polymer in the form of a solid filament as a built material.

Material extrusion additive manufacturing

thermoplastic polymer

filament

as

material


Input: The polymer melts inside the hot-end channel and flows under the pressure generated by the filament feeding force.

polymer melts

filament

channel

pressure

force


Input: The flow of polymer through the hot-end is not fully understood yet, as it involves many complex phenomena, such as phase transition, shear rate and temperature dependent viscosity, as well as viscoelastic effects.

polymer

as

as

as

as

transition

temperature

viscosity


Input: In this paper, we investigate experimentally the filament feeding force, as a function of the feeding rate, for different materials (PLA and ABS), liquefier temperatures, nozzle diameters, and lengths of the liquefier.

filament

as

PLA

ABS

force

materials

nozzle diameters

temperatures


Input: Increasing the liquefier length and liquefier temperature are found to extend the linear extrusion regime.

temperature

extrusion


Input: A model solely based on heat transfer considerations is proposed to estimate the maximum feeding rate before the extrusion becomes unstable.

model

heat transfer

extrusion


Input: The modelling results agree well with the measurements.

modelling


Input: The model can be used to select the hot-end design as well as appropriate printing parameters.

model

parameters

be

as

as

design


Input: This paper details a novel study and manufacturing approach of fiber alignment in flexible hybrid carbon fiber composites using Material extrusion.

manufacturing approach

Material extrusion

fiber alignment

carbon fiber


Input: Varying carbon fiber volume fractions from 0 to 4 vol% was melt blended with a masterbatch of TPU + 10 wt% MWCNT followed by extrusion.

carbon fiber

melt

extrusion


Input: The final extrudate was then filament wound onto a spool and two different filament layout orientations, 0° and 45°, were printed to compare their mechanical properties to validate the effect of fiber alignment during the printing process for these flexible fiber composites.

extrudate

filament

filament

fiber composites

spool

orientations

mechanical properties

fiber alignment

printing process


Input: The 0° printed composites exhibited up to 34% improvement in stiffness as compared to the 45° composite.

composites

as

composite

stiffness


Input: To validate this fiber orientation, the flexible composite was textured using fiber-debonding and pullout phenomenon and the surfaces were visually and quantifiably characterized using SEM images and surface roughness respectively.

fiber orientation

composite

surfaces

images

SEM

surface roughness


Input: To further elucidate the fiber alignment as indicated by the surface roughness, a water contact angle hydrophobicity test was conducted to prove that the 0° printed composite showed higher contact angle as compared with the 45° orientation, confirming greater entrapment due to fiber alignment at the surface.

fiber alignment

fiber alignment

as

composite

as

surface roughness

contact

contact

orientation

surface


Input: These composites are expected to find future potential in high strength and surface texturing applications.

composites

strength

surface texturing


Input: Conventional material extrusion additive manufacturing is capable of building complex structures.

material extrusion additive manufacturing

complex structures


Input: Overhanging features require the use of support structures.

Overhanging features

support structures


Input: Printing the support structure requires additional time and material.

support structure

material


Input: Conventional processes need time to remove support material and may lead to degraded surface finish.

processes

support material

lead

surface finish


Input: The use of support structures can be avoided by dynamically reorienting the build-platform.

support structures

be


Input: This paper presents a novel approach to build accurate thin shell parts using supportless extrusion-based additive manufacturing.

build

accurate

shell

additive manufacturing


Input: We describe the layer slicing algorithm, the tool-path planning algorithm, and the neural network-based compensated trajectory generation scheme to use a 3 degree of freedom build-platform and a 3 degree of freedom extrusion tool to build accurate thin shell parts using two manipulators.

layer

tool-path

build

algorithm

algorithm

planning

extrusion

accurate

shell

manipulators


Input: Such thin shell parts can not be built without supports by previous supportless AM processes.

shell

be

supports

AM processes


Input: We illustrate the usefulness of our algorithms by building several thin shell parts.

algorithms

shell


Input: Material extrusion (MEX) is a well established production method in additive manufacturing.

Material extrusion

production

additive manufacturing


Input: However, internal residual strains are accumulated during the layer-by-layer fabrication process.

residual

layer-by-layer

fabrication


Input: They bring about shape distortions and a degradation of mechanical properties.

degradation

mechanical properties


Input: In this paper, an in-situ distributed measurement of residual strains in MEX fabricated thermoplastic specimens is achieved for the first time.

in-situ

residual

fabricated

measurement


Input: This innovative measuring system consists of an Optical Backscatter Reflectometry (OBR) interrogation unit connected to a distributed fiber optic strain sensor which is embedded during the MEX process.

Optical

fiber

strain

sensor

process


Input: The characteristic residual strain distribution inside 3D printed components is revealed and numerically validated.

residual

distribution

3D printed


Input: The main mechanisms of residual strain creation and the sensing principles of in-situ OBR are described.

residual

in-situ

sensing


Input: A minimum measuring range of 4 mm and a spatial resolution of 0.15 mm were experimentally demonstrated.

range

resolution

mm

mm


Input: The potential of in-situ OBR technology for detecting invisible manufacturing defects was shown by a trial experiment.

in-situ

technology

defects

experiment

manufacturing


Input: To aid in the transition of 3D printed parts from prototypes to functional products it is necessary to investigate the mechanical anisotropy induced by the Fused Filament Fabrication (FFF) process.

transition

prototypes

process

3D printed parts

mechanical anisotropy

Fused Filament Fabrication

FFF


Input: Since the mechanical properties of an FFF part are most greatly affected by the bead orientation and printed density, or solidity ratio, techniques to precisely control these variables are required.

mechanical properties

FFF

bead

density


Input: An open source Python program, SciSlice, was developed to create the desired tool paths/layer orientations and convert them into machine commands (e.g.

source

tool

machine

orientations


Input: G-Code).

G-Code


Input: SciSlice was then used to develop tool paths which either directly printed tensile specimens or printed sheets from which specimens could be water-jet cut.

tool paths

tensile specimens

sheets

be


Input: The effects of proper bed leveling and feed wheel adjustment are noted and a careful analysis of both bead orientation and solidity ratio are presented.

bed

feed

bead


Input: Finally, it is shown that with proper bead orientation, low layer heights, and a maximum solidity ratio, tensile strengths within 3% of injection molded parts are achievable.

bead

layer heights

tensile strengths


Input: In this paper the authors present a novel design tool for realizing dielectric structures with spatially varying electromagnetic properties via additive manufacturing (AM).

design

dielectric

properties

additive manufacturing

AM


Input: To create tool paths ideal for AM processes, space-filling curves were utilized.

tool paths

AM processes


Input: Using fused deposition modeling (FDM), spatially varying structures were printed that produced a spatially varying relative permittivity.

fused deposition modeling

FDM


Input: Furthermore, the authors verified that this design tool can be applied to practical structures by designing, printing and testing a gradient index flat lens.

design

be

testing

lens


Input: Strain-rate dependence is anisotropic in Material Extrusion Additive Manufacturing.

anisotropic

Material Extrusion Additive Manufacturing


Input: Strain-rate dependence in ME-AM is different from compression molded products.

ME-AM

compression


Input: Ree-Eyring flow rule can adequately describe the yield kinetics of ME-AM components.

ME-AM

components


Input: Compression molded samples show brittle stress-strain behavior.

Compression

brittle

samples


Input: Several ME-AM samples show semi-ductile stress-strain behavior.

ME-AM


Input: The strain-rate dependence of the yield stress for Material Extrusion Additive Manufacturing (ME-AM) polylactide samples was investigated.

yield stress

Material Extrusion Additive Manufacturing

ME-AM

samples


Input: Apparent densities of the ME-AM processed tensile test specimens were measured and taken into account in order to study the effects of the ME-AM processing step on the material behavior.

ME-AM

ME-AM

tensile test

step

material


Input: Three different printing parameters were changed to investigate their influence on mechanical properties, i.e.

parameters

mechanical properties


Input: infill velocity, infill orientation angle, and bed temperature.

infill

infill

bed


Input: Additionally, compression molded test samples were manufactured in order to determine bulk properties, which have been compared to the ME-AM sample sets.

compression

samples

manufactured

properties

ME-AM


Input: Anisotropy was detected in the strain-rate dependence of the yield stresses.

Anisotropy

yield stresses


Input: The Ree-Eyring modification of the Eyring flow rule is able to accurately describe the strain-rate dependence of the yield stresses, taking two molecular deformation processes into account to describe the yield kinetics.

accurately

yield stresses

deformation


Input: The results from this paper further show a change from a brittle behavior in case of compression molded samples to a semi-ductile behavior for some of the ME-AM sample sets.

brittle

compression

samples

ME-AM


Input: This change is attributed to the processing phase and stresses the importance that the temperature profile (initial fast cooling combined with successive heating cycles) and the strain profile during ME-AM processing have on the resulting mechanical properties.

phase

mechanical properties

temperature

profile

profile

cooling

heating

ME-AM

strain


Input: Both these profiles are significantly different from the thermo-mechanical history that material elements experience during conventional processing methods, e.g.

profiles

thermo-mechanical

material elements


Input: injection or compression molding.

compression molding


Input: This paper can be seen as initial work that can help to further develop predictive numerical tools for Material Extrusion Additive Manufacturing, as well as for the design of structural components.

be

as

as

as

tools

Material Extrusion Additive Manufacturing

design

structural components


Input: This study investigates the suitability of direct write (DW) technology for the fabrication of high-resolution wear sensors.

investigates

technology

fabrication

high-resolution

sensors


Input: The sintered lines exhibited an electrical resistivity of 5.29 × 10−8 Ω m (about three times bulk silver resistivity reported in the literature) with a standard deviation of 3.68 × 10-9 Ω m (ca.

sintered

electrical resistivity

standard deviation

silver

ca

resistivity


Input: 7% variation).

variation


Input: To determine the conditions needed to consistently create fine conductive lines, we simulated the volumetric flow rate and analyzed the effects on line geometry of several printing parameters including valve opening, dispensing gap, and substrate translation speed.

flow rate

geometry

parameters

substrate


Input: Our results indicate decreasing the valve opening, decreasing the dispensing gap, and/or increasing the translation speed of the substrate reduces the resultant printing flow rate and cross-sectional area of DW lines.

translation speed

flow rate

area

substrate