Input: With reference to the Ti6Al4V alloy and manufacturing by electron beam melting, we perform systematic finite element modeling of one-pass scanning to study the effects of beam size, beam power density, beam scan speed, and chamber bed temperature on the magnitude and distribution of residual stresses.

Ti6Al4V alloy

manufacturing

electron beam melting

finite element

scanning

distribution

beam

beam

beam

bed

density

residual stresses

magnitude


Input: Our study elucidates both qualitative and quantitative features of the residual stress fields originated by these manufacturing parameters.

qualitative

quantitative

residual stress

manufacturing


Input: Our findings can serve as useful guidelines for engineers and designers to deal with residual stress build-up during additive manufacturing of Ti6Al4V.

as

residual stress

additive manufacturing


Input: LCAs of ten 3D printers were compared in different temporal & spatial utilizations.

3D printers


Input: Utilization alone is not enough; energy use and print materials are also critical.

print

materials


Input: Previous studies on the environmental impacts of polymeric additive manufacturing (AM) have shown that higher printer utilization dramatically improves impacts per part—so much so that it might dominate all other interventions if taken to an extreme.

additive manufacturing

AM

printer


Input: In this study, life cycle assessments (LCAs) were performed for an inkjet fusion printer with exceptionally high spatial utilization capacity and were compared to previous LCAs of nine printers printing with eight materials.

life cycle

fusion

capacity

materials

inkjet

printers


Input: Comparisons were performed in different utilizations, both temporal and spatial, to determine if high utilization reduces the environmental impact of AM more than other interventions, such as using sustainable print materials.

impact

sustainable

materials

AM

print

as


Input: For the inkjet fusion printer, maximum utilization dramatically reduced the environmental impact per part to less than 1% of its impact in lowest utilization; this was below the impacts of other printers in low utilizations.

inkjet

fusion

impact

impact

printers


Input: However, when compared in the same utilization scenarios, the inkjet fusion printer still caused a higher environmental impact per part than almost all printers, primarily due to high energy use.

inkjet

fusion

impact

printers


Input: The lowest-impact printer used both high spatial utilization and low-impact materials that also enabled a low-energy printing process.

printer

materials

printing process


Input: Therefore, printer utilization is not the overriding factor and must be combined with energy efficiency and material choice.

printer

be

material


Input: Ultrasonic cavitation abrasive finishing reduced Ra on metal additively manufactured sloping and side surfaces by up to 40%.

cavitation

surfaces

abrasive

metal

additively manufactured


Input: No excessive removal occurs in UCAF as mass and dimensional changes induced by UCAF are dependent on the initial surface morphology.

as

surface morphology


Input: Internal surfaces of a 3 mm diameter channel were finished to less than 4 μm Ra.

surfaces

diameter

mm

channel


Input: Moderate abrasive size and concentration led to a balance between the two mechanisms of surface roughness improvement.

abrasive

led

surface roughness


Input: The poor and non-uniform surface quality of parts produced by powder bed fusion (PBF) processes remains a huge limitation in additive manufacturing.

surface quality

powder bed fusion

PBF

additive manufacturing

processes


Input: Here we show that ultrasonic cavitation abrasive finishing (UCAF) could improve the surface integrity of PBF surfaces built at various orientations –0°, 45° and 90°.

cavitation

orientations

abrasive

surface integrity

PBF


Input: Average surface roughness, Ra, was reduced from as high as 6.5 μm on side surfaces (90°) to 3.8 μm.

Average

surfaces

roughness

as

as


Input: Surface morphological observations showed extensive removals of surface irregularities and peak reduction on sloping (45°) and side surfaces.

Surface

surface

reduction

surfaces


Input: The micro-hardness of the first 100 μm of the surface layer was enhanced up to 15% post-UCAF.

surface

layer


Input: A parametric study further showed the effect of abrasive size, abrasive concentration, ultrasonic amplitude and working gap on UCAF’ s performance.

abrasive

abrasive

s

performance


Input: A moderate abrasive size at 12.5 μm and concentration level at 5 wt% resulted in the lowest final Ra; as the two dominant material removal mechanisms–direct cavitation erosion and micro-abrasive impacts–were balanced.

abrasive

as

material

cavitation


Input: Finally, UCAF was demonstrated to result in 20% Ra improvement of internal surfaces of a 3 mm diameter channel.

surfaces

diameter

mm

channel


Input: Microstructure of an additively manufactured AlSi10Mg through direct metal laser sintering (DMLS) process is studied using multi-scale characterization techniques including scanning electron microscopy, electron backscatter diffraction, and transmission electron microscopy.

Microstructure

process

additively manufactured

direct metal laser sintering

DMLS

scanning electron microscopy

electron backscatter diffraction

transmission electron microscopy


Input: The microstructure of DMLS-AlSi10Mg consists of hierarchical characteristics, spanning three order of magnitude, where nanometer sized to sub-millimeter scaled features exist in the structure.

microstructure

structure

magnitude

nanometer


Input: These characteristics included grain and cell structures, nanoscale Si precipitates and pre-existing dislocation networks.

grain

dislocation

cell

Si

precipitates


Input: Dynamic mechanical behavior of the material is studied using a Split Hopkinson Pressure Bar apparatus over a range of strain rates varying between 800 s−1 and 3200 s−1.

Dynamic

Pressure

strain rates

material

range


Input: Investigation of the deformed microstructures reveals the role of hierarchical microstructure on the dynamic behavior of the material.

deformed

microstructure

dynamic

material


Input: The high strain-rate deformation is accommodated by dynamic recovery (DRV) process, where low angle grain boundaries evolve due to the generation of dislocations, evolution of dislocation networks, and annihilation of dislocations.

deformation

dynamic

process

grain boundaries

dislocations

evolution

dislocation

dislocations


Input: Both cell walls and Si precipitates contribute to impeding the dislocation motion and development of dislocation networks.

cell

Si

precipitates

dislocation motion

dislocation


Input: At high strain rates, dislocation networks evolve in the nanoscale DRVed subgrains.

strain rates

dislocation

subgrains


Input: Metal additive manufacturing (AM) is a rapidly growing field aimed to produce high-performance net-shaped parts.

Metal additive manufacturing

AM


Input: Therefore, bulk metallic glasses (BMGs), known for their superlative mechanical properties, are of remarkable interest for integration with AM technology.

metallic glasses

mechanical properties

AM technology


Input: In this study, we pioneer the utilization of commercially available BMG sheetmetal as feedstock for AM, using laser foil printing (LFP) technology.

as

foil

LFP

AM

laser

technology


Input: LFP and traditional casting were used to produce samples for four-point bending and Vickers hardness measurements to rigorously compare the mechanical performance of samples resulting from these two fabrication techniques.

LFP

casting

bending

fabrication

samples

samples

Vickers hardness

mechanical


Input: Through LFP, fully amorphous BMG samples with dimensions larger than the critical casting thickness of the same master alloy were successfully made, while exhibiting high yield strength and toughness in bending.

LFP

alloy

samples

dimensions

casting

bending

yield strength

toughness


Input: This work exemplifies a potential method to fabricate high-value BMG commercial parts, like gears or mechanisms, where the parts are conventionally machined after printing, and greatly benefit from utilizing novel materials.

fabricate

machined

gears

materials


Input: In industry, Design for Additive Manufacturing (DfAM) is currently synonymous with expert knowledge and external consultants for many companies.

industry

companies

Design for Additive Manufacturing


Input: Particularly in higher cost technologies, such as metal powder bed fusion, component design requires extensive additive manufacturing (AM) knowledge.

technologies

as

powder bed fusion

additive manufacturing

AM

component


Input: If a part is improperly designed, then it can cause thousands of dollars of lost time and material through a failed print.

designed

material

print


Input: To avoid this situation, specialists must be consulted throughout the printing process; however, the shortage of trained personnel familiar with AM can create a bottleneck during design.

be

printing process

AM

bottleneck

design


Input: In order to help businesses identify candidate parts for Powder Bed Fusion (PBF) AM, this paper presents a DfAM worksheet to help engineers, drafters, and designers select good part candidates with little prior knowledge of the specific technology.

Powder Bed Fusion

PBF

AM

technology


Input: This worksheet uses data from the literature to support the values used for design guidance.

data

support

design


Input: Example components are shown to demonstrate the worksheet process.

components

process


Input: Ratings of these components are then compared with expert raters’ assessments of their suitability for fabrication with PBF from a geometric standpoint.

components

fabrication

PBF


Input: In recent years, combining additive and subtractive manufacturing technologies has attracted much attention from both industrial and academic sectors.

additive

subtractive manufacturing

industrial


Input: Thereafter, the design of process planning for combining additive and subtractive manufacturing processes is focused.

design

process planning

processes

additive

subtractive manufacturing


Input: This allows achieving the geometry and quality of final part from the existing part.

geometry

quality


Input: The methodology for process planning design is developed in two major steps using the manufacturing feature concept, the knowledge of manufacturing processes, technological requirements, and available resources.

methodology

process planning

design

feature

manufacturing

manufacturing processes


Input: In the first step, manufacturing features (i.e.

step

manufacturing


Input: machining and additive manufacturing features) are extracted from the information of the existing and final parts.

machining

additive manufacturing

extracted


Input: In the second step, the process planning is generated from extracted features by respecting the relationships of features and the manufacturing precedence constraints.

step

process planning

extracted

manufacturing


Input: Finally, a case study is used to illustrate the proposed methodology.

case study

methodology


Input: Although vibration-assisted powder delivery systems have been developed and studied in the literature, their characteristics and principles of operation are generally not well suited for powder-based additive manufacturing operations mainly because of their powder flows and deposition characteristics.

powder delivery systems

powder-based additive manufacturing

powder

deposition


Input: The flow rate, one of the key parameters in these processes, was used to evaluate the system.

flow rate

parameters

processes


Input: Its sensitivity and dependence on powder particle size, piezo excitation frequency and amplitude, hopper volume, nozzle size, and humidity were assessed.

sensitivity

powder particle

excitation

volume

nozzle


Input: The results, using 316 L stainless steel powders, have shown that the mass powder flow rate can be effectively controlled and that it is most prominently influenced by the piezo excitation frequency.

316 L stainless steel powders

be

powder flow rate

excitation


Input: Ti6Al4V + Al12Si compositionally graded cylindrical structures were fabricated on a Ti6Al4V substrate using laser engineered net shaping (LENS™) process.

Ti6Al4V substrate

cylindrical

fabricated

process

laser engineered net shaping


Input: LENS™ fabricated materials had two regions of Ti6Al4V + Al12Si compositions, a pure Al12Si, and a pure Ti6Al4V area.

fabricated

area


Input: Microstructural changes were affected by both laser power and compositional variations.

Microstructural

variations

laser power


Input: In addition, TiSi2 and Ti3Al phase formations were also identified in low and high laser power processed Ti6Al4V + Al12Si sections, respectively.

phase

laser power


Input: Moreover, the high laser power processed Ti6Al4V + Al12Si section showed the highest hardness value of 685.6 ± 10.6 HV0.1, which was caused due to the formation of new intermetallic phases.

laser power

intermetallic

hardness


Input: This high hardness section exhibited brittle failure modes during compression tests, while the pure Al12Si sections showed ductile deformation.

hardness

ductile

brittle failure

deformation

compression tests


Input: The maximum compressive strengths of Ti6Al4V + Al12Si compositionally graded material was 507.8 ± 52.0 MPa.

compressive strengths

material

MPa


Input: Our results show that compositionally gradient bulk structures of Ti6Al4V and Al12Si can be directly manufactured using additive manufacturing, however, performances can vary significantly based on process parameters and compositional variations.

be

manufactured

process parameters

variations

additive manufacturing


Input: Additive manufacturing (AM) enables highly complex-shaped and functionally optimized parts.

Additive manufacturing

AM

complex-shaped


Input: However, as today’ s computer-aided design (CAD) tools are still based on low-level, geometric primitives, the modeling of complex geometries requires many repetitive, manual steps.

as

s

computer-aided design

CAD

modeling

tools

complex geometries


Input: As a consequence, the need for an automated design approach is emphasized and regarded as a key enabler to quickly create different concepts, allow iterative design changes, and customize parts at reduced effort.

As

as

design

design


Input: Topology optimization exists as a computational design approach but usually demands a manual interpretation and redesign of a CAD model and may not be applicable to problems such as the design of parts with multiple integrated flows.

Topology optimization

design

design

as

be

as

CAD model


Input: This work presents a computational design synthesis framework to automate the design of complex-shaped multi-flow nozzles.

design

design

framework

complex-shaped

nozzles


Input: The framework provides AM users a toolbox with design elements, which are used as building blocks to generate finished 3D part geometries.

framework

AM

design

as

3D part


Input: The elements are organized in a hierarchical architecture and implemented using object-oriented programming.

elements

architecture


Input: As the layout of the elements is defined with a visual interface, the process is accessible to non-experts.

As

elements

layout

interface

process


Input: As a proof of concept, the framework is applied to successfully generate a variety of customized AM nozzles that are tested using co-extrusion of clay.

As

clay

framework

AM


Input: Finally, the work discusses the framework’ s benefits and limitations, the impact on product development and novel AM applications, and the transferability to other domains.

framework

impact

product development

s

AM


Input: 17-4PH stainless steel thin-walled samples were additively manufactured by SLM Samples parallel and at 45˚ to the scan axes gave beam path lengths of 19-0.8 mm Longer beam paths gave microstructures comprising mostly coarse-grained ferrite The shortest beam paths gave structures with mostly austenite and some martensite Re-heating of ferrite leads to austenite, with martensite forming during cooling Components with varying dimensions are found in numerous applications.

steel

microstructures

ferrite

austenite

martensite

ferrite

austenite

martensite

samples

Samples

additively manufactured

SLM

mm

forming

cooling

beam

beam

beam

Components

dimensions


Input: The current work examines how microstructures and phases change for additively manufactured 17-4PH thin walls as a function of laser path length, path direction, and wall thickness.

microstructures

as

additively manufactured

laser

wall thickness


Input: Two sample sets were designed, each consisting of four walls with thicknesses of 6.4 mm to 0.8 mm.

sample

designed

mm

mm


Input: In the first set, the wall axes were parallel to the scan axes, such that the laser path length varied from layer to layer with the laser path either being parallel or perpendicular to the wall.

set

laser

laser

layer

layer


Input: In the second set, the walls lay at 45° to the scan axes, such that the laser path had the same length in all layers and gradually decreased with wall thickness.

set

lay

laser

wall thickness


Input: Substantial changes in phase stability and microstructure are observed as the wall thickness decreases, with ferritic phases and coarse grains changing to fine grains and an increasing volume fraction of austenite.

phase

microstructure

grains

grains

as

ferritic

austenite

wall thickness

volume fraction


Input: These changes are attributed to changes in the local temperature-time profile as the length of the laser paths change from 19 mm to 0.8 mm.

profile

as

laser

mm

mm


Input: These observations demonstrate the range of microstructure and phase control options available in additive manufacturing with judicious selections of part layouts on build plates and of laser beam directions.

range

microstructure

phase

laser beam

additive manufacturing

build plates


Input: In this paper, the anisotropy in the nickel-aluminum bronze (NAB) component manufactured by WAAM process has been shown and investigated by different methods including material and mechanical tests.

anisotropy

bronze

NAB

material

component

WAAM

process

mechanical tests


Input: The quenching and tempering heat treatments have been used in this paper to reduce the anisotropy.

quenching

tempering

heat treatments

anisotropy


Input: Results have indicated that the quenching and tempering heat treatments can effectively reduce the anisotropy in the NAB component.

quenching

tempering

heat treatments

anisotropy

NAB

component


Input: Results have shown that the additively manufactured materials possess relatively better tensile performances.

additively manufactured

tensile


Input: In this paper, a nickel-aluminum bronze alloy component is built using wire-arc additive manufacturing process.

bronze alloy

wire-arc additive manufacturing process


Input: In order to investigate the influence of anisotropy introduced by the wire-arc additive manufacturing process, the layer-by-layer manufactured components with different post-production heat treatments are characterized by optical and scanning electron microscopy morphologies, X-ray diffraction and mechanical tests in longitudinal, transverse and normal directions.

anisotropy

wire-arc additive manufacturing process

heat treatments

layer-by-layer

morphologies

components

optical

scanning electron microscopy

X-ray diffraction

mechanical tests


Input: Also, the ductility of the alloy is significantly improved with the designed quenching and tempering method, and competitive mechanical properties are achieved when tempering temperature reaches 650 °C.

ductility

alloy

designed

tempering

tempering

mechanical properties

temperature


Input: In addition, the anisotropy in the additively manufactured alloy can be effectively modified by the quenching and tempering heat treatments.

anisotropy

additively manufactured

quenching

tempering

heat treatments

be


Input: Selective laser sintering (SLS) is one of the most popular industrial polymer additive manufacturing processes with applications in aerospace, biomedical, tooling, prototyping, and beyond.

Selective laser sintering

SLS

additive manufacturing processes

industrial

aerospace

biomedical

tooling

prototyping


Input: SLS is capable of creating unique, functional parts with little waste and no tooling by using a high-powered laser to selectively melt powdered polymer into desired shapes.

SLS

tooling

melt

laser

polymer


Input: This process relies heavily on understanding and controlling the thermodynamics of the polymer melt process.

process

polymer melt


Input: One of the biggest challenges SLS faces is lack of adequate process control, which leads to comparatively high component variations.

SLS

process control

component


Input: It has been shown that implementing more advanced laser control techniques enable a higher level of control over the processing temperatures and lead to more uniform components.

laser

temperatures

lead

components


Input: Currently, there are no commercial options for a laser power controller that allows continuously variable power to be used as a galvanometer system adjusts the laser position.

laser power

power

controller

be

as

laser


Input: Process consistency and control are bottleneck issues to wider insertion of powder-bed fusion additive manufacturing in the industrial shopfloor.

Process consistency

bottleneck

fusion

additive manufacturing

industrial


Input: Of particular interest is the porosity of the components, which remains the limiting factor to high-cycle fatigue performance.

porosity

fatigue

components


Input: Recent experiments have shown that, with increasing energy density, a surge in porosity is seen in selectively laser melted metals.

energy density

porosity

laser

metals


Input: In this high-energy density regime, porosity must originate from mechanisms that are different from the well-known incomplete melting in the low energy density regime.

density

porosity

melting

energy density


Input: To shed light on this interesting phenomenon, this paper first discusses the mechanism of bubble formation in the melt pool and possible trapping during the solidification, and then formulates a predictive model for porosity in this regime.

mechanism

solidification

predictive model

melt pool

porosity


Input: To compare with experimental results, we perform computer modeling and simulations which have been fully validated by experiments to determine the parameters in the model.

experimental

parameters

model

computer

simulations


Input: We show that the model predictions are in good qualitative and quantitative agreement with the experimental measurements.

model

qualitative

quantitative

experimental


Input: Hence, the proposed model can be used as a tool to predict the porosity, and further to control and possibly reduce porosity in laser powder-bed fusion additive manufacturing, paving the way for its wider adoption in manufacturing shopfloors.

model

fusion

be

as

tool

porosity

porosity

laser

additive manufacturing

manufacturing


Input: Laser powder bed fusion (LPBF) uses a focused, high power laser to repeatedly scan geometric patterns on thin layers of metal powder, which build up to a final, solid three-dimensional (3D) part.

Laser powder bed fusion

LPBF

power

build

laser

metal powder

three-dimensional


Input: This process is somewhat limited in that the parts tend to have poorer surface finish (compared to machining or grinding) and distortion due to residual stress, as well as multiple other deficiencies.

process

distortion

surface finish

machining

grinding

residual stress

as

as


Input: Typical laser scan strategies are relatively simple and use constant laser power levels.

laser scan

simple

laser power


Input: This elicits local variations in the melt pool size, shape, or temperature, particularly near sharp geometric features or overhang structures due to the relatively higher thermal conductivity of solid metal compared to metal powder.

variations

melt pool

metal

metal powder

temperature

overhang

thermal conductivity


Input: In this paper, we present a new laser power control algorithm, which scales the laser power to a value called the geometric conductance factor (GCF).

laser power

laser power

algorithm


Input: The GCF is calculated based on the amount of solid vs. powder material near the melt pool.

powder material

melt pool


Input: Then, we detail the hardware and software implementation on the National Institute of Standards and Technology (NIST) additive manufacturing metrology testbed (AMMT), which includes co-axial melt pool monitoring using a high-speed camera.

software

Standards

Technology

additive manufacturing

melt pool

camera


Input: Six parts were fabricated out of nickel superalloy 625 (IN625) with the same nominal laser power, but with varying GCF algorithm parameters.

fabricated

algorithm

nickel

laser power


Input: We demonstrate the effect of tailored laser power on reducing the variability of melt pool intensity measured throughout the 3D build.

laser power

variability

melt pool


Input: Finally, we contrast the difference between the ‘optimized’ part vs. the standard build parameters, including the deflection of the final part top surface near the overhang and the variation of surface finish on the down-facing surfaces.

standard

surface

variation

surfaces

build parameters

overhang

surface finish


Input: Ultimately, the improvements to the in-situ process monitoring and part qualities demonstrate the utility and future potential tuning and optimizing more complex laser scan strategies.

in-situ

laser scan


Input: Powder-fed laser additive manufacturing (LAM) based on directed energy deposition (DED) technology is used to produce S316-L austenitic, and S410-L martensitic stainless steel structures by 3D-printing through a layer-upon-layer fashion.

laser additive manufacturing

LAM

directed energy deposition

DED

technology

fashion

austenitic

martensitic stainless steel


Input: The microstructural features and crystallographic textural components are studied via electron backscattering diffraction (EBSD) analysis, hardness indentation and tensile testing.

microstructural

components

diffraction

EBSD

tensile testing

hardness


Input: The results are compared with commercial rolled sheets of austenitic and martensitic stainless steels.

sheets

austenitic

martensitic stainless steels


Input: A well-developed < 200 > direction solidification texture (with a J-index of ∼11.5) is observed for the austenitic structure produced by the LAM process, compared to a J-index of ∼2.0 for the commercial austenitic rolled sheet.

solidification

austenitic

austenitic

sheet

LAM


Input: Such a texture in the LAM process is caused by equiaxed grain formation in the middle of each layer followed by columnar growth during layer-upon-layer deposition.

texture

LAM

equiaxed grain

deposition

layer


Input: A quite strong preferred orientation (J-index of 17.5) is noticed for martensitic steel developed by LAM.

orientation

steel

LAM


Input: Large laths of martensite exhibit a dominant textural component of {011} < 111 > in the α-phase, which is mainly controlled by transformation during layer-by-layer deposition.

martensite

component

layer-by-layer deposition


Input: On the other hand, the martensitic commercial sheet consists of equiaxed grains without any preferred orientation or completely random orientations.

sheet

equiaxed grains

orientation

orientations


Input: In the case of the austenitic steel, mechanical properties such as tensile strength, hardness and ductility were severely deteriorated during the LAM deposition.

austenitic

as

mechanical properties

deposition

strength

hardness

ductility

LAM


Input: A ductility loss of about 50% is recorded compared to the commercially rolled sheets that is attributed to the cast/solidified structure.

ductility

sheets

structure


Input: However, LAM manufacturing of martensitic stainless steel structures leads to a considerably enhanced mechanical strength (more than double) at the expense of reduced ductility, because of martensitic phase transformations under higher cooling rates.

LAM

martensitic stainless steel

mechanical strength

ductility

phase

cooling rates


Input: Electrophoretic deposition (EPD) is a widely used industrial coating technique for depositing polymer, ceramic, and metal thin films.

Electrophoretic deposition

industrial

coating

polymer

ceramic

metal


Input: Recently, there has been interested in using EPD for additive manufacturing using reconfigurable electrodes.

additive manufacturing

electrodes


Input: We demonstrate a resolution limit of 10 μm for the deposited feature, which corresponds to the limits of the optical system.

resolution

limit

limits

feature

optical


Input: Furthermore, the first 3D overhanging structure made with EPD is presented, which points to the ability to create architected cellular materials.

structure

cellular materials


Input: These improvements open the possibility for EPD to be a true 3D additive manufacturing technique.

be

manufacturing


Input: Addresses thermal annealing of additively manufactured polymer parts.

thermal annealing

additively manufactured


Input: Demonstrates significant enhancement in thermal conductivity.

thermal conductivity


Input: Data quantify dependence of enhancement on annealing time and temperature.

Data

annealing

temperature


Input: Develops a theoretical thermal model, with good agreement with measurements.

theoretical

model


Input: Results may help improve thermal performance of polymer AM parts.

performance

polymer

AM parts


Input: While additive manufacturing offers significant advantages compared to traditional manufacturing technologies, deterioration in thermal and mechanical properties compared to properties of the underlying materials is a serious concern.

additive manufacturing

traditional manufacturing

technologies

mechanical properties

properties

materials


Input: In the context of polymer extrusion based additive manufacturing, post-process approaches, such as thermal annealing have been reported for improving mechanical properties based on reptation of polymer chains and enhanced filament-to-filament adhesion.

polymer extrusion

additive manufacturing

annealing

post-process

mechanical properties

as

polymer

adhesion


Input: However, there is a lack of similar work for improving thermal properties such as thermal conductivity.

thermal properties

as

conductivity


Input: This paper reports significant enhancement in build-direction thermal conductivity of polymer extrusion based parts as a result of thermal annealing.

thermal conductivity

polymer extrusion

thermal annealing

as


Input: A theoretical model based on Arrhenius kinetics for neck growth and a heat transfer model for the consequent impact on inter-layer thermal contact resistance is developed.

theoretical model

heat transfer

impact

contact


Input: Predicted thermal conductivity enhancement is found to be in good agreement with experimental data for a wide range of annealing temperature and time.

Predicted

experimental data

conductivity

be

range

annealing


Input: The theoretical model may play a key role in developing practical thermal annealing strategies that account for the multiple constraints involved in annealing of polymer parts.

theoretical model

thermal annealing

annealing

polymer


Input: This work may facilitate the use of polymer extrusion additive manufacturing for producing enhanced thermal conductivity parts capable of withstanding thermal loads.

polymer extrusion additive manufacturing

thermal conductivity


Input: Additively manufactured metamaterials such as lattices offer unique physical properties such as high specific strengths and stiffnesses.

Additively manufactured

as

as

physical properties

specific strengths


Input: However, additively manufactured parts, including lattices, exhibit a higher variability in their mechanical properties than wrought materials, placing more stringent demands on inspection, part quality verification, and product qualification.

additively manufactured

lattices

variability

mechanical properties

quality

wrought materials

inspection


Input: Previous research on anomaly detection has primarily focused on using in-situ monitoring of the additive manufacturing process or post-process (ex-situ) x-ray computed tomography.

research

anomaly

in-situ

post-process

additive manufacturing process

x-ray computed tomography


Input: In this work, we show that convolutional neural networks (CNN), a machine learning algorithm, can directly predict the energy required to compressively deform gyroid and octet truss metamaterials using only optical images.

neural networks

images

machine learning algorithm

truss

metamaterials

optical


Input: Using the tiled nature of engineered lattices, the relatively small data set (43 to 48 lattices) can be augmented by systematically subdividing the original image into many smaller sub-images.

lattices

data

lattices

image

be


Input: During testing of the CNN, the prediction from these sub-images can be combined using an ensemble-like technique to predict the deformation work of the entire lattice.

testing

prediction

deformation

lattice

be


Input: This approach provides a fast and inexpensive screening tool for predicting properties of 3D printed lattices.

tool

properties

3D printed


Input: Importantly, this artificial intelligence strategy goes beyond ‘inspection’, since it accurately estimates product performance metrics, not just the existence of defects.

inspection

accurately

performance

defects


Input: Plaster Binder Jetting (BJ) is one of the major Additive Manufacturing (AM) technologies which has been in use since the 1990s.

Binder Jetting

BJ

Additive Manufacturing

AM

technologies


Input: It has many advantages such as the ability to print in full color CMY (K), no support structures, and is relatively faster and less expensive when compared to other AM technologies.

as

K

print

AM technologies

support structures


Input: Since there is no phase transformation (e.g.

phase


Input: powder to molten pool in powder bed fusion, directed energy deposition), BJ does not require support structures and enables higher packing density in the build volume.

powder

molten pool

powder bed fusion

directed energy deposition

BJ

support structures

density

build volume


Input: However, relatively lower mechanical strength when compared to other AM processes has mostly limited it to non-functional applications such as prototyping.

mechanical strength

AM processes

as


Input: This paper investigates novel methods to improve the mechanical and temperature performance of plaster BJ additive manufactured parts via improved infiltration processes and incorporation of infiltrants with higher strength.

investigates

performance

infiltration

mechanical

additive manufactured parts

temperature

BJ

strength


Input: Potential applications include functional end use products, including tooling, jigs and fixtures for higher temperature applications.

tooling

jigs

temperature


Input: Three 2-part epoxy resin systems were evaluated as infiltrants in comparison to epoxy and cyanoacrylate (CA) resins recommended by the original equipment manufacturer (OEM).

epoxy

as

epoxy

CA

resins

equipment


Input: Multiple impregnation methods including hot and wet vacuum were evaluated on their infiltration effectiveness.

impregnation

infiltration effectiveness


Input: The best impregnation method was then used to prepare tensile, flexural and compressive samples for additional evaluation of each resin.

impregnation

tensile

samples

resin


Input: Both resins and infiltrated samples were individually evaluated using Differential Scanning Calorimetry (DSC) to determine glass transition temperatures and other thermal events.

resins

samples

Scanning

glass transition temperatures

DSC


Input: Infiltrated specimens of the best performing resins were evaluated for Heat Deflection Temperature (HDT) performance utilizing Dynamic Mechanical Analysis (DMA).

resins

Heat Deflection

performance

Dynamic Mechanical Analysis

DMA


Input: It was found that infiltration is anisotropic, with the higher penetration depth from the sides (between layers) than top and bottom (across layers).

infiltration

anisotropic

penetration depth


Input: Vacuum impregnation resulted in the highest infiltration depth by fully impregnating the 25 mm cubic samples.

impregnation

mm

infiltration

samples


Input: The best performing epoxy showed a 10% increase in mechanical strength over the OEM epoxy at 76% reduction in cost.

epoxy

epoxy

mechanical strength

reduction


Input: The OEM cyanoacrylate had the lowest mechanical strength across all tests.

mechanical strength


Input: DSC analysis revealed that the plaster and gypsum base material will start to dehydrate above 100 °C and will ultimately limit the parts’ high temperature capabilities.

DSC

gypsum

material

limit

temperature


Input: The OEM epoxy showed the highest HDT.

epoxy


Input: High residual stresses are typical in additively manufactured metals and can reach levels as high as the yield strength, leading to distortions and even cracks.

residual stresses

yield strength

additively manufactured

as

as


Input: Here, an in situ method for controlling residual stress during laser powder bed fusion additive manufacturing was demonstrated.

in situ

residual stress

laser powder bed fusion additive manufacturing


Input: By illuminating the surface of a build with homogeneously intense, shaped light from a set of laser diodes, the thermal history was controlled thereby reducing the residual stress in as-built parts.

surface

build

set

diodes

laser

residual stress


Input: 316L stainless steel bridge-shaped parts were built to characterize the effect of in situ annealing on the residual stress.

316L stainless steel

in situ

annealing

residual stress


Input: A reduction in the overall residual stress value of up to 90% was realized without altering the as-built grain structure (no grain growth).

reduction

grain structure

grain growth

residual stress


Input: Some annealing effects on the cellular-dendritic solidification structure (patterns of higher solute content) occurred in areas that experienced prolonged exposure to elevated temperature.

annealing

solidification

exposure

areas

temperature


Input: A comparison of the in situ process to conventional post-build annealing demonstrated equivalent stress reduction compared to rule-of-thumb thermal treatments.

in situ

reduction

annealing

thermal treatments

stress


Input: Use of this method could reduce or remove the need for post processing to remove residual stresses.

post processing

residual stresses


Input: Metallic cellular solids are a class of materials known for their high specific mechanical properties, being desirable in applications where a combination of high strength or stiffness and low density are important.

Metallic

materials

mechanical properties

strength

stiffness

density


Input: These lightweight materials are often stochastic and manufactured by foaming or casting.

lightweight

stochastic

manufactured

casting


Input: If regular (periodic) lattice structures are desired, they may be manufactured by metallic additive manufacturing techniques.

lattice structures

be

metallic additive manufacturing


Input: However, these have characteristic issues, such as un-melted powders, porosity and heterogeneous microstructures.

as

powders

porosity

heterogeneous


Input: This study reports a novel low-cost route for producing regular lattice structures by an additive manufacturing assisted investment casting technique.

lattice structures

additive manufacturing

investment casting


Input: Fused filament fabrication is used to produce the lattice structure pattern which is infiltrated with plaster.

Fused filament fabrication

lattice structure


Input: The pattern is then burnt off and the aluminum is cast in vacuum.

pattern

aluminum

cast


Input: In this way we can manufacture non-stochastic metallic lattices having fine struts/ribs (0.6 mm cross-section using a 0.4 mm nozzle) and relative densities down to 0.036.

manufacture

lattices

metallic

mm

mm

relative densities


Input: X-ray micro computed tomography (μCT) showed that as-cast A356 Aluminium alloy frameworks have high dimensional tolerances and fine detail control.

X-ray micro computed tomography

dimensional tolerances

Aluminium alloy


Input: Frameworks based on units of six connected struts ranging from intruding (auxetic) to protruding (hexagonal) strut angles are studied.

struts

strut

hexagonal


Input: Vertical struts are finer than expected, reducing their moment of area which could impact their compressive strength.

Vertical

impact

struts

area

compressive strength


Input: This new, low cost, route for producing high precision metallic cellular lattices offers an attractive alternative to other additive manufacturing techniques (e.g.

precision

metallic

lattices

additive manufacturing


Input: selective laser and electron beam melting).

selective laser

electron beam melting


Input: Fine equiaxed dendrites and discrete Laves phase were obtained using alow pulse frequency.

dendrites

Laves phase


Input: Discrete distribution of δ-phase and high-density precipitation of γ″-Ni3Nb were obtained.

distribution

precipitation


Input: A good combination of strength and ductility was obtained by optimizing the microstructures.

strength

ductility

microstructures


Input: Controlling of Nb-rich intermetallics is an important topic for laser additive manufacturing (LAM) of Inconel 718.

intermetallics

Inconel 718

laser additive manufacturing

LAM


Input: In the present work, a novel quasi-continuous-wave LAM (QCW-LAM) with different pulse frequencies is used to control the morphology, distribution and amount of Nb-rich phases of Inconel 718.

LAM

morphology

distribution

Inconel 718


Input: The results show that dispersively distributed Nb-rich Laves phases are produced by introducing equiaxed dendrites at a low pulse frequency while a high pulse frequency results in coarse and chain-like Laves phases.

Laves phases

Laves phases

dendrites


Input: The samples featured by fine and discrete Laves phases show a good response to the post solution-aging treatment in which the dissolution of Laves-phase and subsequently discrete precipitations of δ-phase as well as high-density precipitation of γ″-Ni3Nb strengthening phase are promoted.

samples

Laves phases

precipitation

strengthening phase

as

as


Input: Thus, a good combination of strength and ductility is achieved for the QCW-LAM fabricated Inconel 718.

strength

ductility

fabricated


Input: This study shows a desired mechanical property can be obtained by synergistically optimizing the microstructures in which various Nb-rich phases are involved even though the formation of brittle Laves phases is hardly avoided during LAM of Inconel 718.

mechanical property

be

microstructures

Inconel 718

brittle

LAM


Input: This paper discusses the effects of process parameters in TIG based WAAM for specimens created using Hastelloy X alloy (Haynes International) welding wire and 304 stainless-steel plate as the substrate.

process parameters

TIG

WAAM

welding

Hastelloy

alloy

as

substrate


Input: The Taguchi method and ANOVA were used to determine the effects of travel speed, wire feed rate, current, and argon flow rate on the responses including bead shape and size, bead roughness, oxidation levels, melt through depth, and the microstructure.

Taguchi method

melt

microstructure

feed

argon

bead

bead

oxidation


Input: Increasing travel speed or decreasing current caused a decrease in melt through depth and an increase in roughness.

melt

roughness


Input: No observable interface between the layers was present suggesting a complete fusion between layers with no oxidation.

interface

fusion

oxidation


Input: The zones were characterized by the size and distribution of the molybdenum carbide formations within the matrix grain formations.

distribution

grain

molybdenum carbide


Input: Reactive-deposition additive manufacturing was employed to manufacture titanium-based metal matrix composites for improving the wear resistance and temperature capability of commercially pure titanium (CPTi); a standard material in the aerospace, biomedical, and marine industries, among others.

additive manufacturing

manufacture

standard

metal matrix composites

titanium

material

wear resistance

temperature

aerospace

biomedical

marine industries


Input: Composites were manufactured by leveraging in situ high-temperature reactions between CPTi, zirconium (Zr), and boron nitride (BN) powders during laser-based directed-energy-deposition (DED) 3D-printing.

Composites

zirconium

Zr

boron nitride

BN

powders

manufactured

in situ

DED


Input: The effect of Zr and BN on the processability, phase formation (s), surface wear, and mechanical properties of 3D-printed titanium was studied by printing commercially-pure titanium with premixed additions of 20 wt% Zr and 10 wt% BN using Laser Engineered Net Shaping (LENS™).

Zr

BN

s

titanium

Zr

BN

phase

surface

mechanical properties

Laser Engineered Net Shaping


Input: In the as-printed BN-containing structures, phase analysis revealed reinforcing ceramic phases TiN, TiB, and TiB2, whose presence was substantiated through first-principles analysis.

phase

ceramic

TiN


Input: The combined addition of Zr and BN produced a Ti-Zr alloy matrix with BN-particle and in situ phase-reinforced microstructure with 450% higher hardness (from 318 ± 26 HV0.1/15 to 1424 ± 361 HV0.5/15), a stabilized sliding−COF within 50 m of reciprocating wear testing, and 9x lower final wear rate in comparison to LENS™ deposited titanium.

Zr

BN

alloy

titanium

in situ

microstructure

wear

wear

hardness

testing


Input: Zr-addition alone revealed a combined alloyed and particle-reinforced composite with 12% higher hardness, 23% higher compressive yield strength, and an 11% decrease in final wear rate compared to LENS™-produced titanium.

composite

titanium

hardness

yield strength

wear


Input: Our results demonstrate that reactive-deposition based additive manufacturing can be exploited to create unique coatings and net-shape alloyed structures to enhance the surface and bulk properties of standard engineering materials such as titanium.

additive manufacturing

be

engineering materials

as

coatings

surface

properties

standard


Input: We propose a simple method to construct a process map for additive manufacturing using a support vector machine.

simple

additive manufacturing

process

support

machine


Input: By observing the surface of the built parts and classifying them into two classes (good or bad), this method enables a process map to be constructed in order to predict a process condition that is effective at fabricating a part with low pore density.

surface

process

process

be

fabricating

pore density


Input: This proposed method is demonstrated in a biomedical CoCr alloy system.

biomedical

alloy


Input: This study also shows that the value of a decision function in a support vector machine has a physical meaning (at least in the proposed method) and is a semi-quantitative guideline for porosity density of parts fabricated by additive manufacturing.

support

machine

porosity density

fabricated

additive manufacturing


Input: In binder jetting additive manufacturing (BJAM), the part geometry is generated via a binding agent during printing and structural integrity is imparted during sintering at a later stage.

binder jetting additive manufacturing

sintering

geometry

structural integrity


Input: This separation between shape generation and thermal processing allows the sintering process to be uniquely controlled and the final microstructural characteristics to be tailored.

sintering

process

microstructural

be

be


Input: The separation between the printing and consolidation steps offers a unique opportunity to print responsive materials that are later “activated” by temperature and/or environment.

consolidation

materials

print

temperature


Input: This concept is preliminarily demonstrated using a foaming copper feedstock, such that the copper is printed, sintered and then foamed via intraparticle expansion in separate steps.

copper

copper

sintered


Input: The integration of foaming feedstock in BJAM could allow for creation of ultra-lightweight structures that offer hierarchical porosity, graded density, and/or tailored absorption properties.

feedstock

porosity

density

absorption


Input: This work investigates processing protocol for copper foam structures to achieve the highest porosity.

investigates

protocol

copper

porosity


Input: The copper feedstock was prepared by distributing copper oxides through the copper matrix via mechanical milling, and that powder was then printed into a green geometry through BJAM.

copper

copper oxides

copper

powder

mechanical milling

geometry


Input: The printed green parts were then heat treated using different thermal cycles to investigate the porosity evolution relative to various heating conditions.

green parts

porosity

heat

evolution

thermal cycles

heating


Input: The heat treated parts were then examined for their resulting properties including porosity, microstructural evolution, and volumetric shrinkage.

heat

properties

microstructural evolution

shrinkage

porosity


Input: Parts that were initially sintered in air and then annealed in a hydrogen atmosphere led to higher porosity compared to those sintered in hydrogen alone.

sintered

sintered

led

porosity


Input: Anisotropy in linear shrinkage in X, Y, and Z direction was also observed in the heat treated parts with the largest linear shrinkage occurring in the Z direction.

Anisotropy

shrinkage

heat

shrinkage

Y


Input: Additive manufacturing that allows layer by layer shaping of complex structures is of rapidly increasing interest in production technology.

Additive manufacturing

production

layer by layer

complex structures


Input: A particularly rapid prototyping technique of additive manufacturing is laser beam melting (LBM).

rapid prototyping

additive manufacturing

laser beam


Input: This 3D printing method is based on a powder bed fusion technique, using a high-powered laser to melt and consolidate metallic powders.

3D printing

powder bed fusion

laser

melt

metallic powders


Input: The process needs a tightly controlled atmosphere of inert gas, which requires a confined space of a building chamber.

process

inert gas

building chamber


Input: This and more process related factors like elevated temperatures, laser radiation or the resulting light intensity caused by the melting of metals, make a closed-loop quality control very ambitious.

process

quality control

temperatures

laser

melting

metals


Input: In this paper, we propose a new in-process approach for quality control with high precision metrology based on structured light.

quality control

metrology

precision


Input: The precise layer by layer dimensional measurement of both the printed part and the powder deposition, allows for process assessment in- or off-line.

layer by layer

deposition

process

measurement

powder


Input: For laser powder bed fusion (L-PBF) additive manufactured (AM) metals, residual stress-induced cracking often occurs at the interface between the solid and lattice support, and hence it is important to characterize the as-built critical J-integral of the interface to prevent cracking to occur.

laser powder bed fusion

L-PBF

additive manufactured

AM

metals

residual

cracking

interface

lattice

interface

cracking


Input: However, the standard testing method for the critical J-integral of the interface (ASTM E1820-01) does not work well in this situation for four reasons: 1) standard test blocks consisting of half solid and half lattice support crack during the printing process; 2) even after reinforcing the block with side walls to prevent cracking, post-stress relief causes the yield strength to change significantly, which would affect J-integral significantly; 3) post-build machining processes to obtain the required standard specimen geometry release a significant amount of residual stress, which also gives incorrect J-integral value; 4) the interface is so brittle that it is very difficult to machine it to the required standard configuration.

standard

interface

standard

lattice

cracking

standard

geometry

interface

standard

configuration

printing process

machining

yield strength

residual stress

brittle

machine


Input: Hence a more effective method that combines printing experiments and residual stress simulation is proposed to determine the as-built critical J-integral of the interface.

residual stress

interface


Input: Next, the experimentally-validated modified inherent strain method is utilized to simulate residual stress and compute the critical J-integral at where the interfacial cracking occurs.

modified inherent strain method

cracking

residual stress


Input: The proposed method is subsequently validated using the obtained critical J-integral to predict cracking in different geometries.

cracking

geometries


Input: This method eliminates the uncertainties associated with stress relaxation by heat treatment and machining on mechanical properties, as well as sheds light on crack prediction for as-built L-PBF components.

stress relaxation

mechanical properties

prediction

heat treatment

machining

L-PBF

as

as

components


Input: This study aims to investigate the fabrication feasibility of a conventionally rolled low-carbon low-alloy shipbuilding steel plate (EH36) by emerging wire arc additive manufacturing (WAAM) technology using ER70S feedstock wire.

fabrication

wire arc additive manufacturing

WAAM

steel

feedstock

technology


Input: Following the fabrication process, different heat treatment cycles, including air-cooling and water-quenching from the intercritical austenitizing temperature of 800 °C, were applied to both conventionally rolled and WAAM samples.

fabrication

heat treatment

austenitizing

WAAM

samples


Input: Microstructural features and mechanical properties of both rolled and WAAM fabricated ship plates were comprehensively characterized and compared before and after different heat treatment cycles.

Microstructural

mechanical properties

fabricated

WAAM

heat treatment


Input: Both air-cooling and water-quenching heat treatments resulted in the formation of hard martensite-austenite (MA) constituents in the microstructure of the rolled ship plate, leading to the increased hardness and tensile strength and reduced ductility of the component.

heat treatments

microstructure

hardness

tensile strength

ductility

component


Input: On the other hand, air-cooling heat treatment was found to homogenize the microstructure of the WAAM ship plate, causing a slight decrease in the hardness and tensile strength, while the water-quenching cycle led to the formation of acicular ferrite and intergranular pearlite, contributing to the improved mechanical properties of the part.

heat treatment

WAAM

microstructure

mechanical properties

hardness

tensile strength

led

ferrite

pearlite


Input: Therefore, the enhanced mechanical integrity of the water-quenched WAAM component as compared to its rolled counterpart verified the fabrication feasibility of the ship plates by the WAAM.

mechanical integrity

WAAM

fabrication

WAAM

component

as


Input: The ability to combine multiple materials (MM) into a single component to expand its range of functional properties is of tremendous value to the ceaseless optimization of engineering systems.

materials

properties

optimization

MM

component

range

engineering


Input: Although fusion and solid-state joining techniques have been typically used to join dissimilar metals, additive manufacturing (AM) has the potential to produce MM parts with a complex spatial distribution of materials and properties that is otherwise unachievable.

fusion

solid-state

materials

properties

joining

additive manufacturing

AM

MM

metals

spatial distribution


Input: In this work, the selective laser melting (SLM) process was used to manufacture MM parts which feature steep material transitions from 316L stainless steel (SS) to Ti-6Al-4V (TiA) through an interlayer of HOVADUR® K220 copper–alloy (CuA).

selective laser melting

SLM

process

manufacture

feature

material

316L stainless steel

SS


Input: The microstructure in both the CuA/SS and TiA/CuA interfaces were examined in detail and the latter was found to be the critical interface as it contained three detrimental phases (i.e.

microstructure

interface

be

as


Input: L21 ordered phase, amorphous phase, and Ti2Cu) which limit the mechanical strength of the overall MM part.

phase

phase

limit

mechanical strength

MM


Input: By making use of the non-homogeneity within the melt pool and limiting the laser energy input, the relatively tougher interfacial α′-Ti phase can be increased at the expense of other brittle phases, forming what is essentially a composite structure at the TiA/CuA interface.

melt pool

be

laser energy

phase

composite structure

interface

brittle

forming


Input: During tensile testing, the interfacial α′-Ti phase is capable of deflecting cracks from the relatively brittle TiA/CuA interface towards the ductile CuA interlayer and an overall tensile strength in excess of 500 MPa can be obtained.

tensile testing

phase

interface

MPa

brittle

ductile

tensile strength

be


Input: This method of introducing an interfacial composite structure to improve MM bonding is envisioned to be applicable for the SLM of other metallic combinations as well.

composite structure

bonding

MM

SLM

be

metallic

as


Input: A stereolithographic approach based on thiol-ene click chemistry is developed to 3D print preceramic polymers into infusible thermosets.

chemistry

3D print

polymers


Input: Three classes of preceramic polymers, including siloxane, carbosilane and carbosilazane, are additively manufactured.

polymers

additively manufactured


Input: Upon pyrolysis, thermosets transform into glassy ceramics with uniform shrinkage and high density.

pyrolysis

ceramics

shrinkage

density


Input: A fabricated SiOC honeycomb exhibits a significantly higher compressive strength to weight ratio in comparison to other porous ceramics.

fabricated

honeycomb

compressive strength

porous

weight

ceramics


Input: Here we introduce a versatile stereolithographic route to produce three different kinds of Si-containing thermosets that yield high performance ceramics upon thermal treatment.

performance

ceramics

thermal treatment


Input: Due to the rapidity and efficiency of the thiol-ene click reactions, this additive manufacturing process can be effectively carried out using conventional light sources on benchtop printers.

additive manufacturing process

be

light sources

printers


Input: Through pyrolysis the thermosets transform into glassy ceramics with uniform shrinkage and high density.

pyrolysis

ceramics

shrinkage

density


Input: The obtained ceramic structures are nearly fully dense, have smooth surfaces, and are free from macroscopic voids and defects.

ceramic

fully dense

smooth surfaces

macroscopic

defects


Input: A fabricated SiOC honeycomb was shown to exhibit a significantly higher compressive strength to weight ratio in comparison to other porous ceramics.

fabricated

honeycomb

compressive strength

porous

weight

ceramics


Input: Schematic representation of the stereolithographic additive manufacturing of preceramic polymers into intricately patterned thermosets assisted by thiol-ene click chemistry and their subsequent conversion into ceramics.Download: Download high-res image (189 Advances in multi-material additive manufacturing have enabled advancements in the manufacture of composite materials.

additive manufacturing

multi-material additive manufacturing

polymers

composite materials

chemistry

high-res image

manufacture


Input: In this work, a family of thermite-based reactive materials is created and evaluated for the suitability as composite energetic structures.

reactive materials

as


Input: The burn rate with respect to binder ratio is observed to be highly predictable and exponential (coefficients of determination of rTi2=0.984 and rAl2=0.973), with composites transitioning from one binder mass fraction to another.

binder

be

composites

binder

predictable

fraction


Input: To create composites, a single layered syringe and nozzle are used in conjunction with continuous filament direct ink writing.

composites

filament

ink

syringe

nozzle


Input: The resulting prints show success in composite structure with a transition zone between printed materials.

composite structure

transition

materials


Input: These results show both a variety of thermite-based energetics with easily modifiable reaction rates and a technique to print said reactive materials to create composite structures.

reaction rates

print

reactive materials

composite structures


Input: Space agencies are looking for advanced technologies to build light weight and stiff payload components to bear space environment and launch loads.

technologies

build

weight

components


Input: Additive manufacturing (AM) techniques like Direct Metal Laser Sintering (DMLS) is one of the suitable option which can be explored for space applications.

Additive manufacturing

AM

Direct Metal Laser Sintering

DMLS

be


Input: This paper highlights the development process of Antenna Feed Array (AFA) using DMLS as an Additive Manufacturing (AM) technique.

process

Feed

DMLS

Additive Manufacturing

AM

as


Input: Such horns are preferred for this development as they are the prime choice for feed elements in High Throughput satellites (HTS) that employ Multibeam Antennas.

as

elements

feed

Throughput


Input: In the development process, certain design rules of AM are adopted based on consideration to produce self-sustaining structures.

process

design rules

AM


Input: AFA realized by DMLS is evaluated by functional testing, vibration testing for space qualification test levels.

DMLS

testing

testing


Input: Variations in local processing parameters and conditions in additively manufactured materials make mechanical properties difficult to characterize.

Variations

parameters

mechanical properties

additively manufactured


Input: Microtensile testing is providing a wealth of information on these local property variations.

testing

property variations


Input: Here we utilize spatial autocorrelation techniques to show autocorrelation of grain sizes and mechanical properties with build height in a specially-designed, additively manufactured AlSi10Mg part.

grain sizes

mechanical properties

build height

additively manufactured


Input: This result suggests that, at least in some cases, an interplay between local part geometry and the fabrication process occurs that affects local mechanical properties.

geometry

mechanical properties

fabrication


Input: Complex thermal behaviour during fabrication plays an import role in the geometrical formation and mechanical properties of Ti6Al4V components manufactured using Wire Arc Additive Manufacturing (WAAM) technology.

fabrication

Wire Arc Additive Manufacturing

WAAM

mechanical properties

technology

components


Input: In this study, through in-situ temperature measurement, the heat accumulation and thermal behaviour during the gas tungsten wire arc additive manufacturing (GT-WAAM) process are presented.

in-situ

gas

process

measurement

heat accumulation

wire arc additive manufacturing


Input: The effects of heat accumulation on microstructure and mechanical properties of additively manufactured Ti6Al4V parts were studied by means of optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and standard tensile tests, aiming to explore the feasibility of fabricating Ti6Al4V parts by GT-WAAM using localized gas shielding.

heat accumulation

microstructure

mechanical properties

standard

feasibility

gas

additively manufactured

fabricating

optical microscopy

OM

X-ray diffraction

XRD

scanning electron microscopy

SEM

energy dispersive spectrometer

EDS


Input: The results show that due to the influences of thermal accumulation, the layer’ s surface oxidation, microstructural evolution, grain size, and crystalline phase vary along the building direction of the as-fabricated wall, which creates variations in mechanical properties and fracture features.

layer

building direction

s

oxidation

microstructural evolution

phase

variations

mechanical properties

fracture

grain size


Input: It has also been found that it is necessary to maintain the process interpass temperature below 200 °C to ensure an acceptable quality of Ti6Al4V part fabricated using only localized gas shielding in an otherwise open atmosphere.

process

quality

fabricated

gas

interpass temperature


Input: This research provides a better understanding of the effects of heat accumulation on targeted deposition properties during the WAAM process, which will benefit future process control, improvement, and optimization.

research

deposition

process

process control

optimization

heat accumulation

WAAM


Input: A novel binder-free 3D printing method with zero process contaminants is developed.

binder-free

3D printing

process contaminants


Input: The first ever study on employing microwave (MW) sintering for inkjet 3D printing.

microwave

MW

sintering

inkjet 3D printing


Input: Reduction of sintering time up to four times compared to conventional sintering.

Reduction

sintering time

sintering


Input: Discussion on thermal and non-thermal effects in MW sintering of 3D printed parts.

MW sintering

3D printed parts


Input: 3D printing (3DP) is a two-step additive manufacturing technique (AM) in which additively manufactured green parts in the first step are transformed into functional parts during the second step.

3D printing

additive manufacturing

AM

additively manufactured

step

step


Input: Here we use capillary-mediated binderless 3DP as a novel method to additively manufacture green parts of Mg-5.06Zn-0.15 Zr powder.

capillary-mediated binderless 3DP

additively manufacture

as

Mg-5.06Zn-0.15 Zr


Input: A unified perspective on the development steps of process parameters to obtain sufficient handling strength and a high level of dimensional accuracy in the green parts without compromising its chemical composition is established by using a scanning electron microscope, X-ray micro-tomography, vibrational spectroscopy, and chemical analysis.

process parameters

chemical composition

handling strength

green parts

dimensional accuracy

X-ray micro-tomography

chemical analysis

scanning electron microscope

vibrational spectroscopy


Input: For the first time, microwave (MW) sintering is successfully used for densification of the green parts with centimeter-scale dimensions in which the primary chemical composition of the Mg-Zn-Zr powder is retrieved from the green parts, resulting in a compositionally zero-sum AM process.

microwave

MW

centimeter-scale dimensions

chemical composition

sintering

densification

AM process

green parts

green parts

Mg-Zn-Zr powder


Input: It is found that swelling leads to loss of shape fidelity during MW sintering of the green parts at temperatures ≥ 510 °C.

swelling

shape fidelity

MW sintering

green parts

temperatures


Input: As discussed in the context of thermal and non-thermal effects, MW significantly reduced sintering time by a factor of three to four times when compared to sintering in a conventional furnace.

As

MW

sintering time

sintering

conventional furnace


Input: The results of this study suggest the notion of capillary-mediated binderless 3DP as well as MW sintering as a potential alternative for the first and second steps of 3DP, respectively.

capillary-mediated binderless 3DP

sintering

as

as

as


Input: Wire and arc additive manufacturing of HSLA steel was performed.

Wire and arc additive manufacturing

steel


Input: Microstructure and mechanical properties were related to the thermal cycles.

Microstructure

mechanical properties

thermal cycles


Input: No preferential texture was developed, leading to near-isotropic mechanical properties.

texture

mechanical properties


Input: As-built parts exhibited excellent ductility and high mechanical strength.

ductility

mechanical strength


Input: Wire and arc additive manufacturing (WAAM) is a viable technique for the manufacture of large and complex dedicated parts used in structural applications.

Wire and arc additive manufacturing

WAAM

manufacture


Input: High-strength low-alloy (HSLA) steels are well-known for their applications in the tool and die industries and as power-plant components.

steels

as

tool

die

components


Input: The microstructure and mechanical properties of the as-built parts are investigated, and are correlated with the thermal cycles involved in the process.

microstructure

mechanical properties

correlated

process

thermal cycles


Input: The heat input is found to affect the cooling rates, interlayer temperatures, and residence times in the 800–500 °C interval when measured using an infrared camera.

heat

infrared

cooling rates

temperatures

camera


Input: The microstructural characterization performed by scanning electron microscopy reveals that the microstructural constituents of the sample remain unchanged.

microstructural characterization

scanning electron microscopy

microstructural

sample


Input: i.e., the same microstructural constituents—ferrite, bainite, martensite, and retained austenite are present for all heat inputs.

microstructural

heat

bainite

martensite

retained austenite


Input: Electron backscattered diffraction analysis shows that no preferential texture has been developed in the samples.

diffraction

texture

samples


Input: Because of the homogeneity in the microstructural features of the as-built parts, the mechanical properties of the as-built parts are found to be nearly isotropic.

microstructural

mechanical properties

be

isotropic


Input: Mechanical testing of samples shows excellent ductility and high mechanical strength.

Mechanical testing

samples

ductility

mechanical strength


Input: This is the first study elucidating on the effect of thermal cycles on the microstructure and mechanical properties during WAAM of HSLA steel.

thermal cycles

microstructure

mechanical properties

WAAM

steel


Input: Components produced by near net shape additive manufacturing processes often require subsequent subtractive finishing operations to satisfy requisite surface finish and geometric tolerances.

Components

near net shape additive manufacturing

subtractive finishing operations

surface finish

geometric tolerances


Input: It is well established that the microstructure and properties of the as-built component are sensitive to the additive processing history.

microstructure

properties

component

additive


Input: Therefore, downstream secondary processes may be affected by the as-built components’ mechanical behavior.

processes

be

components

mechanical


Input: In this work we study the sensitivity of secondary machining operations on CoCrMo samples produced via laser powder bed fusion.

sensitivity

machining

laser powder bed fusion

samples


Input: Utilizing novel high-throughput mechanical testing, microstructure characterization, and a rigorous statistical analysis we investigate the degree of material anisotropy present in the as-built material.

mechanical testing

microstructure

material

material

anisotropy


Input: We then study the effects of this anisotropy on secondary processing via slot milling experiments.

anisotropy

milling


Input: Our results indicate that mechanical anisotropy is driven by both the morphology of the microstructure as well as crystallographic texture.

mechanical anisotropy

morphology

microstructure

as

as

texture


Input: The machining force response is correspondingly sensitive to these sources of anisotropy, which has the potential to impact how manufacturers finish additively built parts.

machining

force

impact

anisotropy


Input: This study presents a detailed characterization of room temperature bulk microstructure and texture of additively manufactured Ti-6Al-4V alloy samples with the neutron time-of-flight diffractometer HIPPO.

temperature

microstructure

neutron

texture

additively manufactured

alloy


Input: A comparison is made between samples that were manufactured by two different methods utilizing selective laser melting and electron beam melting.

samples

manufactured

selective laser melting

electron beam melting


Input: Analysis of the orientation distribution function shows a dependency upon the particular fabrication technique used as well as on the location within the built body and orientation relative to the build direction.

orientation

distribution

orientation

fabrication

as

as

build direction


Input: It is shown that the texture components strength in the hexagonal phase depends on the relative tilt angle between the build direction and that the overall texture of samples prepared with the electron beam method is weaker than those prepared with the selective laser melting.

texture

hexagonal

tilt angle

texture

components

build direction

samples

electron beam

selective laser melting


Input: Such knowledge on the bulk microstructure allows to optimize additive manufacturing process parameters.

microstructure

additive manufacturing process


Input: One rapidly advancing technology with high space resource utilization potential is additive manufacturing.

technology

additive manufacturing


Input: Additive manufacturing is already prevalent in the aerospace industry and is an enabling technology of significant potential for weight savings, cost reduction, tool repair, and just-in-time manufacturing.

Additive manufacturing

manufacturing

aerospace industry

technology

cost reduction

weight

tool


Input: In the last few years, institutions such as ASTM International and NASA have released standards for additive manufacturing, but research done in the field of additive manufacturing with space resources is still in its infancy.

as

standards

research

additive manufacturing

additive manufacturing


Input: Among the technologies under investigation, powder bed fusion technologies for melting regolith show particular promise due to their efficiency and freedom from binder material.

technologies

powder bed fusion

melting

binder


Input: As strict material and process control is difficult with space resource utilization focused technology, the lessons learned by terrestrial manufacturing experts are still being adapted for use in the burgeoning field.Proposed is a framework for adapting existing standards for use with space resources by identifying specific risks and fundamental factors for part quality, determining part criticality, and documenting material, process controls, environmental conditions, and other influencing factors.

As

material

material

process control

technology

framework

standards

quality

process controls

manufacturing


Input: This research explored the influences of shielding gases on the appearance of weld beads and the microstructures and mechanical properties of thin-wall samples using conventional gas metal arc welding as the heat source by using 5356 aluminium alloy welding wire as the raw materials and nitrogen (N2) and argon (Ar) as the shielding gases.

research

weld beads

mechanical properties

samples

heat source

microstructures

as

aluminium alloy

as

raw materials

nitrogen

argon

as

gas metal arc welding

Ar


Input: The results showed that under the same parameters and after mono-layer single-bead welding was performed using N2 as the shielding gas, the bead height was higher, the bead width was narrower, and the penetration depth was shallower.

parameters

gas

welding

as

bead

bead width

penetration depth


Input: The grain size of the thin-wall sample protected by N2 was 43.5–47.8% smaller than that obtained under Ar protection.

grain size

sample

Ar


Input: However, the sample protected by N2 contained many flaky nitrides, whose presence improved the microhardness but reduced the ultimate tensile strength (UTS) and plasticity.

sample

microhardness

nitrides

ultimate tensile strength

UTS

plasticity


Input: The average UTS of the thin-wall sample protected by N2 in the horizontal direction was 82.5% of the UTS of the samples shielded using Ar.

average

sample

samples

UTS

Ar


Input: However, the average elongation in the horizontal direction of the samples protected by N2 was 18.6% of that of the samples shielded by Ar.

average

samples

samples

Ar


Input: The mechanical properties of the sample protected by argon were more excellent.

mechanical properties

sample

argon


Input: An eco-design for AM framework based on energy performance assessment has been proposed.

AM

performance


Input: A simulation tool has been proposed to predict energy consumption of AM.

simulation

AM


Input: Design mechanisms and the workflow for eco-design for AM have been discussed.

Design

workflow

AM


Input: Additive manufacturing (AM) has been considered as a promising technology with higher resource efficiency and better ecological benefits in production systems.

Additive manufacturing

AM

as

technology

production systems


Input: If the parameters are not designed appropriately, the ecological performance of AM can be worse than conventional manufacturing processes.

parameters

performance

designed

AM

conventional manufacturing

be


Input: To ensure the ecological benefits of AM, eco-design based on Life Cycle Assessment (LCA) is a promising approach to analyze and minimize the environmental impacts of AM.

AM

AM

Life Cycle


Input: However, LCA can only be carried out at the later stage of the design process after most design and decision operations are already made because the implementation of LCA requires detailed process and inventory information of the entire life cycle.

be

design process

process

life cycle

design


Input: If users attempt to optimize the ecological performance of their design solutions, they need to repeat almost the entire design process.

performance

design process

design


Input: The proposed approach uses a holistic framework consisting of three parts: a simulation tool for energy consumption prediction of AM, an assessment model for energy performance of AM, and general workflows of eco-design for AM.

framework

prediction

model

performance

workflows

simulation

AM

AM

AM


Input: Since the energy performance quantification and assessment of AM require less process information, it can be integrated earlier and easier into the eco-design for AM.

performance

process

AM

AM

be


Input: Additionally, an example of use case is provided that confirms the feasibility of this framework.

feasibility

framework


Input: By employing selective laser melting (SLM), we demonstrate how Sn3Ag4Ti alloy can robustly bond to silicon via additive manufacturing.

selective laser melting

SLM

additive manufacturing

alloy

silicon


Input: With this technology, heat removal devices (e.g., vapor chamber evaporators, heat pipes, micro-channels) can be directly printed onto the electronic package without using thermal interface materials.

technology

heat

heat

interface

be


Input: This reduces operating temperature, saving power and reducing electronic-waste.

temperature

power


Input: The bonding of common metal alloys used in additive manufacturing onto silicon is relatively weak and generally possesses high contact angles (poor wetting and interfacial strength).

bonding

metal alloys

silicon

additive manufacturing

contact

strength


Input: By using the proper interlayer material, wettability and reactivity with the silicon substrate increase drastically.

material

silicon

wettability


Input: Unlike conventional dissimilar material brazing that can take tens of minutes to form a strong bond, this study demonstrates how this kinetic limitation can be overcome to form a good bond in sub-milliseconds via intense laser heating.

material

be

brazing

laser

heating


Input: The mechanism for rapid bonding lies in using an alloy that can form a strong intermetallic bond to the substrate at a low temperature, and exposing the sample multiple times to give sufficient diffusion time for a strong bond.

mechanism

bonding

sample

diffusion

alloy

intermetallic

substrate

temperature


Input: Bonding of Sn3Ag4Ti to silicon occurs through the formation of a thin (∼μm) titanium-silicide interfacial layer that makes the silicon wettable to the Sn3Ag4Ti.

Bonding

silicon

silicon

layer


Input: These printed parts are mechanically resistant to thermal cycling, with no mechanical failures visible after over a week of continuous thermal cycling (−40 °C and 130 °C).

thermal cycling

thermal cycling

mechanical failures


Input: Additively manufactured low porosity equiatomic CoCrFeMnNi alloy parts.

Additively manufactured

porosity

alloy


Input: Parts are single phase with inter-cellular regions enriched in Mn and Ni.

phase

Mn

Ni


Input: Tensile properties exceeded most previous work on similar alloys.

Tensile properties

alloys


Input: Initiation of pitting for CoCrFeMnNi alloy was comparable to 304 L stainless steel.

pitting

alloy

stainless steel


Input: This study investigates the mechanical and corrosion properties of as-built and annealed equiatomic CoCrFeMnNi alloy produced by laser-based directed energy deposition (DED) Additive Manufacturing (AM).

investigates

mechanical

corrosion properties

alloy

directed energy deposition

DED

Additive Manufacturing

AM


Input: The high cooling rates of DED produced a single-phase, cellular microstructure with cells on the order of 4 μm in diameter and inter-cellular regions that were enriched in Mn and Ni.

cooling rates

DED

microstructure

diameter

cells

Mn

Ni


Input: Annealing created a chemically homogeneous recrystallized microstructure with a high density of annealing twins.

Annealing

annealing

homogeneous

microstructure

density


Input: The average yield strength of the as-built condition was 424 MPa and exceeded the annealed condition (232 MPa), however; the strain hardening rate was lower for the as-built material stemming from higher dislocation density associated with DED parts and the fine cell size.

average

MPa

MPa

strength

dislocation density

cell size

strain hardening

DED

material


Input: In general, the yield strength, ultimate tensile strength, and elongation-to-failure for the as-built material exceeded values from previous studies that explored other AM techniques to produce the CoCrFeMnNi alloy.

yield strength

ultimate tensile strength

material

alloy

AM techniques


Input: Ductile fracture occurred for all specimens with dimple initiation associated with nanoscale oxide inclusions.

Ductile fracture

oxide inclusions


Input: The breakdown potential (onset of pitting corrosion) was similar for the as-built and annealed conditions at 0.40 VAg/AgCl when immersed in 0.6 M NaCl.

pitting corrosion

NaCl


Input: A passive oxide film depleted in Cr cations with substantial incorporation of Mn cations is proposed as the primary mechanism for local corrosion susceptibility of the CoCrFeMnNi alloy.

oxide

Cr

Mn

as

alloy

mechanism

corrosion


Input: Additive manufacturing (AM) enables the fabrication of complex lattice structures, for which a single part may have hundreds or thousands of individual geometric features.

Additive manufacturing

AM

fabrication

lattice structures


Input: Conventional methods for measuring part geometry and performing quality control, which typically use a small number of low-dimensional measurements, are not well suited for lattice structures.

geometry

quality control

lattice structures


Input: This paper describes a method for scanning and automatically extracting individual features of the lattice and applies this method to characterize AM lattice structures in both two-dimensional and three-dimensional lattices.

scanning

extracting

lattice

two-dimensional

three-dimensional lattices

AM


Input: The research measured 94 lattice parts fabricated from 3 materials in 9 different designs using either a high-resolution document scanner or X-ray computed tomography (CT).

research

lattice

fabricated

materials

designs

high-resolution

X-ray computed tomography

CT


Input: A statistical analysis considered manufacturing variances as a function of material type and part design on a subset of the data, comprising the size and location of over 15,000 individual features.

manufacturing

as

material

design

data


Input: We studied the geometric variations of these struts in uniform, hierarchical and gradated parts.

variations

struts


Input: For a single design and material, the standard deviation of lattice feature size is quite small.

design

material

standard deviation

lattice

feature size


Input: For example, a lattice strut with thickness 0.5 mm has a standard deviation of 30 μm.

lattice

mm

standard deviation


Input: However, when the same process is used to manufacture multiple parts having different designs and from different materials, the standard deviation of feature size can be larger by 2X or more.

process

manufacture

materials

designs

standard deviation

feature size

be


Input: This type of automated measurement and analysis may allow for rigorous monitoring, qualification and control of AM lattice parts in production.

automated measurement

AM

production


Input: The adhesion and merging of adjacent filaments in polymer extrusion based additive manufacturing (AM) plays a key role in determining the thermal and mechanical properties of the built part.

adhesion

filaments

polymer extrusion

additive manufacturing

AM

mechanical properties


Input: It is well known that maintaining the deposited filaments at a high temperature aids in the process of adhesion and merging.

filaments

temperature

process

adhesion


Input: While external mechanisms such as laser and infrared heating have been used in the past to heat up deposited filaments, this paper presents a simpler, less invasive and in situ mechanism for heating of previously deposited layers using a hot metal block integrated with and rastering together with the filament-dispensing nozzle.

as

filaments

metal

infrared

heat

in situ

heating

heating

deposited layers

nozzle


Input: Infrared thermography based quantitative measurement of temperature field along the raster line is carried out for two configurations–a preheater and a postheater traveling ahead of or behind the nozzle respectively.

Infrared

quantitative measurement

temperature

nozzle


Input: In each case, significant temperature rise in the deposited filaments is shown.

temperature

filaments


Input: The measured temperature rise is shown to be a function of process parameters such as raster speed and heater-to-base gap.

temperature

be

as

process parameters


Input: Experimental measurements are shown to agree well with theoretical and simulation models.

Experimental

theoretical

simulation


Input: Cross-section imaging of samples printed without and with the in situ heating clearly show significant improvement in neck growth and filament-to-filament merging compared to the baseline case.

imaging

samples

in situ

heating


Input: Improvement in thermal and structural performance of printed samples is also demonstrated.

structural performance

samples


Input: The improved temperature field and consequently enhanced filament adhesion reported here may help design and build parts with superior thermal and mechanical properties using polymer AM.

temperature

build

filament

polymer

adhesion

design

mechanical properties

AM


Input: Pore structures of additively manufactured metal parts were investigated with X-ray Computed Tomography (XCT).

Pore

additively manufactured

X-ray Computed Tomography


Input: Disks made of a cobalt-chrome alloy were produced using laser-based powder bed fusion (PBF) processes.

alloy

powder bed fusion

PBF

processes


Input: The additive manufacturing processing parameters (scan speed and hatch spacing) were varied in order to have porosities varying from 0.1% to 70% so as to see the effects of processing parameters on the formation of pores and cracks.

additive manufacturing

parameters

parameters

scan speed

hatch spacing

porosities

pores

as


Input: The XCT images directly show three-dimensional (3D) pore structure, along with cracks.

images

three-dimensional

pore


Input: Qualitative visualization is useful; however, quantitative results depend on accurately segmenting the XCT images.

Qualitative

quantitative

images

accurately


Input: Methods of segmentation and image analysis were carefully developed based, as much as possible, on aspects of the images themselves.

image analysis

images

as

as


Input: These enabled quantitative measures of porosity, including how porosity varies in and across the build direction, pore size distribution, how pore structure varies between parts with similar porosity levels but different processing parameters, pore shape, and particle size distribution of un-melted powder trapped in pores.

quantitative

distribution

parameters

particle size distribution

porosity

porosity

pore

porosity

pore

pores

build direction

pore size

powder


Input: These methods could possibly serve as the basis for standard segmentation and image analysis methods for metallic additively manufactured parts, enabling accurate and reliable defect detection and quantitative measures of pore structure, which are critical aspects of qualification and certification.

as

metallic

standard

image analysis

defect

quantitative

additively manufactured

accurate

pore


Input: The aluminium alloy wire 2319 is commonly used for Wire + Arc Additive Manufacturing (WAAM).

aluminium alloy

Wire + Arc Additive Manufacturing

WAAM


Input: It is oversaturated with copper, like other alloys of the precipitation hardening 2 ###series, which are used for structural applications in aviation.

copper

alloys

precipitation hardening


Input: Residual stress and distortion are one of the biggest challanges in metal additive manufacturing, however this topic is not widely investigated for aluminium alloys.

Residual stress

distortion

metal additive manufacturing

aluminium alloys


Input: Neutron diffraction measurements showed that the as-built component can contain constant tensile residual stresses along the height of the wall, which can reach the materials' yield strength.

Neutron diffraction

component

tensile residual stresses

yield strength

materials


Input: These stresses cause bending distortion after unclamping the part from the build platform.

bending

build platform


Input: Two different rolling techniques were used to control residual stress and distortion.

rolling

residual stress

distortion


Input: Vertical rolling was applied inter-pass on top of the wall to deform each layer after its deposition.

Vertical

deposition

rolling

layer


Input: This technique virtually elimiated the distortion, but produced a characteristic residual stress profile.

distortion

residual stress

profile


Input: Side rolling instead was applied on the side surface of the wall, after it has been completed.

rolling

surface


Input: An interesting observation from the neutron diffraction measurements of the stress-free reference was the significantly larger FCC aluminium unit cell dimension in the inter-pass rolled walls as compared to the as-build condition.

neutron diffraction

FCC

aluminium

as

cell


Input: This is a result of less copper in solid solution with aluminium, indicating greater precipitation and thus, potentially contibuting to improve the strenght of the material.

copper

solid solution

aluminium

material

precipitation


Input: This work demonstrates the feasibility of fabricating bulk nanostructured high modulus steels in-situ by additive manufacturing.

feasibility

in-situ

fabricating

additive manufacturing

steels


Input: This ideal match of novel processes and alloy concepts opens up new pathways for lightweight design by producing light, stiff, strong and ductile components with minimal geometric restraints.

processes

lightweight

alloy

design

ductile

components


Input: On the example of an Fe–Ti–B alloy, a conventional processing sequence of melting and casting pre-alloys, gas-atomisation and laser powder bed fusion (selective laser melting) led to finely dispersed metastable particle and matrix phases.

Fe

Ti

B

alloy

melting

casting

laser powder bed fusion

selective laser melting

led

metastable


Input: A simple annealing step transformed them into the desired equilibrium constituents of ductile ferrite (matrix) and light and stiff TiB2 (particles), with only minimal changes in particle size (about 20–150 nm in diameter) and distribution (mainly on the matrix grain boundaries).

simple annealing

equilibrium

particles

particle

diameter

distribution

grain boundaries

ductile


Input: This nano-scaled composite structure promises an extremely attractive property profile, i.e.

composite structure

property

profile


Input: an increased stiffness/ratio at elevated strength and without deteriorated ductility.

strength

ductility


Input: However, the not yet optimized parameters of the laser fusion process led to the formation of few pores and cracks, which prevented the complete assessment of the property profile of the manufactured samples.

parameters

fusion

property

manufactured

laser

led

pores

profile


Input: Material and processing strategies for the further development of this promising lightweight design approach–including the suitability of other powder metallurgy processing routes–are outlined and discussed.

Material

lightweight

design

powder metallurgy


Input: Metal Additive Manufacturing (AM) processes have made it possible to build parts with complex geometric features by adopting a layer-by-layer approach.

Metal Additive Manufacturing

AM

processes

layer-by-layer

build


Input: However, additional support structures are needed to support overhanging surfaces and reduce distortion that may occur in these parts.

support structures

support

surfaces

distortion


Input: This increases the overall build time of the part and leads to additional post processing efforts for removal of support structures.

build time

post processing

removal of support


Input: Further, support structures have a detrimental effect on the surface finish on the areas of the part that come in contact with the supports.

support structures

surface finish

areas

contact

supports


Input: Thus, minimizing the need for support structures and ensuring its maximum removal is essential for an efficient part build in AM.

support structures

build

AM


Input: Part build orientation is the main parameter that influences the need for support structures to build a part.

build orientation

build

parameter

support structures


Input: This paper presents an approach to identify the best build orientation for a part such that the overall part build time is minimized while ensuring maximum removal of supports and minimizing the contact area between the part surface and supports.

build orientation

build time

area

removal of supports

contact

supports

surface


Input: A hierarchical octree data structure has been used to analyze support accessibility and the area of support in contact with part.

data

support

support

contact

area


Input: A 2D setup map highlighting the feasible directions of setups for support removal has also been presented.

support


Input: The estimation for overhang angle of a 3D structural surface is established by fitting the local element density distribution with a density hyperplane in ℝ4 space.

overhang angle

surface

local element density distribution

density


Input: The 3D hanging feature issue is resolved by the combination of horizontal minimum length constraint and overhang angle constraint.

feature

overhang angle


Input: A constraint-based approach for 3D topology optimization with a large number of element-wise constraints is proposed to obtain an accurate solution.

optimization

accurate


Input: This paper studies additive manufacturing oriented structural topology optimization with SIMP approach and aims at 3D high-resolution printable structural topology design with overhang and horizontal minimum length control for minimum compliance.To start with, we construct a hyperplane in ℝ4 by fitting a local element density distribution in the 18 Elements Scheme, use its gradient to estimate the overhang angle, the directional-dependent overhang angle and formulate the corresponding constraints.

additive manufacturing

topology optimization

design

topology

local element density distribution

overhang

overhang angle

overhang angle

Elements


Input: Next, we propose a Horizontal Square Scheme and four support sets around the concerned element.

support

element


Input: The horizontal minimum length was controlled by forbidding the concerned element’ s density to be larger than the average density of the elements in one of the support sets.

element

s

be

elements

density

average

support


Input: By combining these two constraints, the hanging feature is well suppressed.A new implementation scheme with an improved weight function is proposed to meet these element wise AM constraints well.

feature

weight

element

AM


Input: To get high resolution structural boundaries with low computational efforts, this paper applies the multiresolution topology optimization (MTOP) method.The structural TO problem is solved by MMA.

high resolution

boundaries

topology optimization


Input: A number of numerical examples and AM experiments show the effectiveness of this method.

AM

effectiveness