Effect Of Build Orientation Research Articles

In-plane quasi-static compression deformation of Ti6Al4V double arrow-headed lattice structures fabricated by electron beam powder bed fusion process: Build orientation, scan speed and failure mechanism

The 2D double arrow-headed (DAH) lattice structures, which are promising cellular structures for impact mitigation, remain relatively unexplored in terms of their compression response when manufactured using the powder bed fusion process with Ti6Al4V (Ti64) alloy. This study aims to investigate the effects of build orientation and beam scan speed of Electron Beam Powder Bed Fusion (PBF-EB) process on the energy absorption of 2D Ti64 DAH lattice structures. Additionally, potential microstructural variations due to adjusted process parameters can be linked to different levels of energy absorption. For the compressions, the lattice structures were manufactured at two build orientations (0° and 45°), using three different beam scan speeds: speed function (SF), low speed (LS), high speed (HS). In micro-characterizations, the unit cells of 0deg-LS exhibited the lowest micro-porosity level at 0.12 %. Based on KAM values, thin struts at unit cells had higher residual stresses than thick struts, contributing to the initiation of failure locations. The compressions revealed that the 0deg-LS group absorbed 21.6 % and 24 % more energy than 0deg-SF and 0deg-HS groups, respectively, at compressions of 33 %. 45° samples absorbed approximately 10 % more energy than 0° samples except HS groups. The lowest micro-porosity of 0deg-LS contributed to having the highest energy absorption among 0deg samples. As the residual stresses in KAM values did not differ strongly with varying beam speed, varied energy absorptions were not linked to them. An optimization of the numerical compressions helped obtain designs with higher energy absorption and less relative volume. This study provides valuable insights into Ti64 cellular applications constrained with 2D-type designs.

Enhancing Sustainability in Building Design: Hybrid Approaches for Evaluating the Impact of Building Orientation on Thermal Comfort in Semi-Arid Climates

The evaluation of human thermal comfort inside buildings plays a pivotal role in reducing energy consumption and enhancing sustainability in the built environment. The estimation of thermal comfort is based on objective (physical factors) and subjective (psychological factors) aspects. This study aimed to find a hybrid way to evaluate more accurate thermal comfort in the buildings as per their orientations. This study assessed the effect of building orientation on thermal comfort conditions in row houses in semi-arid climates, based on a synthesis of the predictive mean vote (PMV) model and the thermal sensation vote (TSV). For this purpose, row houses were selected in the region of this study. This study concluded that the PMV model calculates a lower thermal comfort level than the TSV method, and that the thermal comfort demand within the houses was higher than ASHRAE Standard 55. The occupants inside the houses had a lower thermal tolerance. This implied that the residents of these buildings can consume more energy during the summer, typically the harshest season. This study presented new mathematical models for occupants’ thermal comfort evaluation in the study region, depending on the building’s orientation. In both models, for assessing thermal performance during both the summer and winter seasons, east-facing buildings consistently ranked as the second-best orientation. This suggested that, overall, east-facing buildings can be considered the best choice throughout the entire year in terms of thermal comfort. This study suggested a novel indicator to evaluate the optimum building orientation in the study area in terms of thermal performance.

The effect of build orientation on tensile properties and corrosion resistance of 316L stainless steel fabricated by laser powder bed fusion

The effects of build orientation on tensile property and corrosion behavior of laser powder bed fusion 316L stainless steel were investigated. The laser powder bed fusion 316L stainless steel in normal direction exhibited lower tensile strength and elongation than one in build direction. In view of the fact that there was no obvious martensitic transformation in the two samples, high density dislocation and more low-angle grain boundaries in laser powder bed fusion 316L stainless steel in build direction both enhanced tensile yield and tensile strength. More deformed twins in the sample in build direction induced better plasticity. In addition, laser powder bed fusion 316L stainless steel in build direction exhibited better corrosion resistance than one in normal direction in borate buffer and sodium chloride solutions. This was attributed to the larger grain and more densely packed crystallographic faces in build direction for laser powder bed fusion 316L stainless steel.

Shrinkage Compensation and Effect of Building Orientation on Mechanical Properties of Ceramic Stereolithography Parts.

Stereolithography additive manufacturing (SLA-AM) can be used to produce ceramic structures by selectively curing a photosensitive resin that has ceramic powder in it. The photosensitive resin acts as a ceramic powder binder, which is burned, and the remaining ceramic part is sintered during post-processing using a temperature-time-controlled furnace. Due to this process, the ceramic part shrinks and becomes porous. Moreover, additive manufacturing leads to the orthotropic behavior of the manufactured parts. This article studies the effect of the manufacturing orientation of ceramic parts produced via SLA-AM on dimensional accuracy. Scaled CAD models were created by including the calculated shrinkage factor. The dimensions of the final sintered specimens were very close to the desired dimensions. As sintering induces porosity and reduces the mechanical strength, in this study, the effect of orientation on strength was investigated, and it was concluded that the on-edge specimen possessed by far the highest strength in terms of both compression and tension.

Creep of IN738LC manufactured with laser powder bed fusion: effect of build orientation and twinning

ABSTRACT The microstructural anisotropy caused by the highly oriented solidification of the metal Laser Powder Bed Fusion (PBF-LB/M) process affects mechanical short- and long-term properties. Component build orientation influences grain morphology and orientation, and thus, mechanical properties. While the creep behaviour of samples manufactured parallel and perpendicular to the build direction are studied intensively, the 45° build orientation remains uncharacterised. In this study, IN738LC creep samples are manufactured via PBF-LB/M in three build orientations (0°, 45° and 90°). While the results of 90° and 0° are as expected, where 90° achieves the longest time to rupture and largest rupture strain, the 45° specimen shows the least fracture time. Differences in microstructure and twinning behaviour are identified as one of the root causes for this unexpected behaviour. This study discusses the correlation between microstructure, twinning and build orientation and their effect on creep behaviour, with special focus on the 45° build orientation.

The Impact of Additive Manufacturing Constraints and Design Objectives on Structural Topology Optimization

To analyze the impact of different objective functions and additive manufacturing (AM) constraints on structural topology optimization, it is necessary to perform an in-depth comparative study. This analysis should consider specific structural design factors, such as compliance, volume, or stress minimization, and assess their effects on the topology optimization for AM. In addition, the inclusion of AM constraints can have a significant influence on various aspects, including optimal part geometry, part volume, support structure volume, and structural performance. Thus, it is essential to investigate and compare these factors to determine the optimal part design for AM. This study focuses on comparing topology optimization results obtained using compliance, stress, or multi-objective minimization, with and without AM constraints. A comparative analysis was conducted in the study, utilizing three structural design examples: cantilever beam, bridge-shaped structure, and L-shaped beam. The comparison results provide insights into the effects of build orientation, AM constraints such as overhang, and different design objectives on the structural topology optimization for AM.

Study of parametric interaction during fused filament fabrication (FFF) using interpretive structural modelling (ISM) followed by experimental analysis

PurposeFused filament fabrication (FFF) is a type of additive manufacturing (AM) based on materials extrusion. It is the most widely practiced AM route, especially used for polymer-based rapid prototyping and customized product fabrication in relation to aerospace, automotive, architecture, consumer goods and medical applications. During FFF, part quality (surface finish, dimensional accuracy and static mechanical strength) is greatly influenced by several process parameters. The paper aims to study FFF parametric influence on aforesaid part quality aspects. In addition, dynamic analysis of the FFF part is carried out.Design/methodology/approachInterpretive structural modelling is attempted to articulate interrelationships that exist amongst FFF parameters. Next, a few specimens are fabricated using acrylonitrile butadiene styrene plastic at varied build orientation and build style. Effects of build orientation and build style on part’s ultimate tensile strength, flexure strength along with width build time are studied. Prototype beams (of different thickness) are fabricated by varying build style. Instrumental impact hammer Modal analysis is performed on the cantilever beams (cantilever support) to obtain the natural frequencies (first mode). Parametric influence on natural frequencies is also studied.FindingsStatic mechanical properties (tensile and flexure strength) are greatly influenced by build style and build orientation. Natural frequency (NF) of prototype beams is highly influenced by the build style and beam thickness.Originality/valueFFF built parts when subjected to application, may have to face a variety of external dynamic loads. If frequency of induced vibration (due to external force) matches with NF of the component part, resonance is incurred. To avoid occurrence of resonance, operational frequency (frequency of externally applied forces) must be lower/ higher than the NF. Because NF depends on mass and stiffness, and boundary conditions, FFF parts produced through varying build style may definitely correspond to varied NF. This aspect is explained in this work.

Geometrical and crystal plasticity modelling: Towards the establishment of a process-structure-property relationship for additively manufactured 316L struts

This paper presents a methodology to establish a process structure property (PSP) relationship for the additive manufacturing (AM) of thin AISI 316L struts, as might be used in coronary stent applications. The methodology is based on a new geometrically based process-structure method for AM process variables, and crystal plasticity finite element (CPFE) modelling that includes the representation of melt pool microstructure morphology and texture. The effects of AM process variables are characterised with respect to ductility, yield strength and UTS across a range of process variables, including hatch spacing, layer thickness and build orientation (two orientations are considered: horizontal and vertical). The CPFE-predicted effect of build orientation is shown to be consistent with experimental test results. The present methodology has allowed identification of optimal hatch spacing and layer thickness for a given laser spot size, power and scanning speed. CPFE modelling of AM melt pool texture is shown to be key to successful prediction of the effects of process variables on mechanical behaviour.

Effects of build orientation and hatch spacing on high-speed milling behavior of L-PBF 316L stainless steel

Abstract Due to the philosophy of the process, the surface roughness is usually high for the parts produced with laser powder bed fusion (L-PBF) additive manufacturing (AM). Parts produced by this method need surface quality improvement processes for many applications. One of the methods used for this purpose is high speed machining (HSM). HSM is a modern manufacturing technique that offers several benefits, including improved productivity, enhanced product quality, and reduced production costs. In addition, HSM can improve the quality of finished products by reducing machining errors. In this study, samples produced with 316L powder in size of 10 × 10 × 5 mm using three different hatch spacings (60, 70, 80 µm) and building orientations (0°, 45°, 90°) were produced by L-PBF method, and HSM process was applied to these samples. In this context, the present study aimed to investigate the effects of porosity, microstructure and microhardness properties of 316L samples produced by L-PBF method using different hatch spacings and build orientations on cutting forces, surface roughness and burr formation in HSM. When the numerical values of the cutting forces were analyzed in both x and y directions, it was observed that the greatest cutting force occurred in the x direction. While the Fx force ranged from 6.23 to 9.35 N, the Fy force ranged from 4.88 to 8.27 N. It has been determined that as the build orientation increases at the same hatch spacing value, the cutting forces increase due to the increased porosity ratio.

Low cycle fatigue behaviour of additive manufactured maraging steel: Influence of build orientation and heat treatment

The effect of build orientation and heat treatment (solution treatment and aging) on low cycle fatigue (LCF) behaviour of additive manufactured (AM) maraging steel, processed via powder bed fusion, using laser beam (PBF-LB) was investigated in the present work. The build orientation has significant influence on LCF behaviour of AM maraging steel. Un-melted defects were found to be the most detrimental to fatigue life. Defects in 90° oriented samples were more damaging than those in 45° and 0° oriented samples. Heat treatment (HT) of the AM maraging steel was found to be very effective in enhancing the fatigue life by 8–10 times due to marked strengthening by precipitation of intermetallic precipitates and reduction in size and number of AM defects. SEM fractography showedthat surface and interior flaws increased susceptibility to crack propagation through the cross-section.

Effects of build orientation and strain rate on the tensile-shear behaviour of polyamide-12 manufactured via laser powder bed fusion

Laser powder bed fusion (L-PBF) of engineering thermoplastics is a well-established additive manufacturing technique. In this work, an experimental investigation of the tensile-shear behaviour of L-PBF processed polyamide-12 (PA12) is presented, with a particular focus on the concurrent effect of build orientation and rate dependency at strain rates ranging from 10−3 to 103s−1. Results show that the deformation behaviour features significant anisotropy at both low and high strain rates, while quasi-static ultimate strength in either tension or shear shows no dependence on the build direction. As the strain rate increases, the tensile strength is characterised by apparent positive rate dependence but remains insensitive to the build orientation; however the shear strength displays significant build orientation-dependent anisotropy, highlighted by the decreasing shear strength of specimens printed in the loading direction. Post-mortem scanning electron microscopy (SEM) demonstrates torn dimples with stretched filaments in quasi-static fractography, while cleavage facets with flake structures retrieved from high-rate loading. A fibrillar structure is observed from high-rate torsional loading indicating adiabatic decohesion during rapid crack propagation. These findings draw attention to the significant anisotropy of L-PBF PA12 parts in a high-rate loading regime and provide directions to improve the current L-PBF techniques.

Effect of build orientation in gloss, roughness and color of 3D-printed resins for provisional indirect restorations.

The purpose of this study was to evaluate the effect of build orientation of 3D-printed provisional resins (3DRs) on gloss (Gs), surface roughness (Sa), maximum profile valley depth (Rv), and color difference (∆E00). PMMA CAD/CAM blocks (Vita Temp/Vita) were sectioned and served as a Control. Four 3DRs (Cosmos-SLA/Yller, Cosmos-DLP/Yller, PriZma-Bioprov/Makertech, Nanolab/Wilcos) were obtained as discs (15-mm diameter, 2.5-mm thickness) in three orientations (0°, 45°, and 90°) using different 3D printers (Form 2/Formlabs, P30/Straumann, Hunter/Flashforge, W3D/Wilcos, respectively). Samples were then cleaned with isopropyl alcohol prior to post-curing in specific post-curing units. Half of the samples' surface was covered with an adhesive tape and submitted to 10,000 toothbrushing (TB) cycles. The Gs and Sa at the brushed and not brushed surfaces were evaluated with a glossmeter (Novo-curve) and a laser confocal microscope (OLS5000) (n=10), which also obtained the Rv and 3D representative images of the interface between not brushed and brushed surfaces. Electron microscopy images of the surface of some samples was also performed (n=3). On another set of samples (n=5), the coordinates of luminosity and color were obtained with a spectrophotometer (Easyshade V) at baseline and after 16.7h and 200h of UVB aging, to calculate the ∆E00 using CIEDE:2000 formula. Additionally, 3DRs photoinitiators were identified using a minispectrometer (USB2000+) (n=5). Data of Gs and Sa were submitted to three-way-, Rv to two-way-, and ∆E00 to mixed-ANOVA tests, followed by Tukey's test (α=0.05). For all variables, results from experimental groups were compared to control using Dunnett's test (α=0.05). Student's t-test was used to compare the control at different TB cycles (Gs, Sa) or aging periods (∆E00) (α=0.05). Build orientation of 3DRs did not influence any of the variables studied. The 10,000 TB cycles resulted in a decrease in Gs and increase in Sa for all resins tested. The control showed higher Gs after 10,000 TB cycles than Cosmos-SLA and Nanolab resins. Compared to all 3DRs, Control presented lower ∆E00 after 200h of UVB aging. All 3DRs presented higher ∆E00 than the clinically acceptable after 200h of UVB aging. Lucirin® TPO was identified in all 3DRs, although PriZma might also present other photoinitiators and Nanolab might present Irgacure 369. Alterations in build orientation are very useful and frequently performed in the day-today of 3D-printing, thus its effect in the optical properties and in the topography of 3D-printed restorations is very relevant. For the evaluated 3D-printed provisional resins, build orientation did not influence any of the variables studied (Gs, Sa, Rv, and ∆E00), even after toothbrushing cycles and UVB aging.

The mechanism behind the effect of building orientation and surface roughness on hydrogen embrittlement of laser powder bed fused Ti-6Al-4V

The interaction between hydrogen and laser powder bed fused (L-PBF) Ti-6Al-4V is investigated, in combination with the influence of (post-)processing parameters, i.e. the building orientation (horizontal vs. vertical) and the surface finish (as-built vs. polished). After an extensive characterisation of the intrinsic properties of the additive manufactured material (including porosity and specimen roughness), its interaction with hydrogen is thoroughly assessed via electrochemical hydrogen charging at room temperature. The stressed martensitic α’ microstructure shows beneficial properties against hydrogen assisted degradation. The higher effective surface area of the as-built material compared to the polished condition offers more opportunities for hydrogen absorption. Hydrogen uptake is also influenced by the orientation of the prior β grains, depending on the building orientation. Furthermore, porosities tend to accumulate hydrogen. Therefore, a flawless (sub)surface layer and a maximal density are essential for optimal safe use of L-PBF Ti-6Al-4V in hydrogen-rich environments.

Anisotropic fatigue performance of directed energy deposited Ti-6Al-4V: Effects of build orientation

Directed energy deposition (DED), an important branch of additive manufacturing technology, has unique processes that attribute to the fatigue performance anisotropy associated with the build orientation of DED materials. However, the mechanism of fatigue performance anisotropy still remains unclear due to multiple factors of the defect and microstructure, which has limited further application of DED materials. This paper investigates the effects of build orientation on the anisotropic fatigue performance of DED Ti-6Al-4V treated with stress relief annealing, specifically the impact of defects and microstructures on fatigue performance anisotropy. The defects in the fully dense DED Ti-6Al-4V are non-directional porosity defects with smooth morphology and high sphericity; the microstructures are mainly characterized by prior-β columnar grains, α colonies and basketweave structures. To represent fatigue performance anisotropy of the material, standard round bar specimens were sampled from three build orientations, i.e., X, Y and Z directions, where Z-direction represents the build direction. These specimens were subsequently subjected to constant amplitude high cycle fatigue tests at the same loading condition and room temperature. The fatigue test results showed that the logarithmic mean fatigue lives of the X- and Y-direction specimens were close to each other, but significantly longer than those of the Z-direction specimens. Fractography and EBSD tests were conducted to explain the causes of fatigue performance anisotropy, suggesting that microstructures are more likely to explain the anisotropy caused by the build orientation than the porosity defects, with crystallographic orientation and α colony being two critical factors.

Effect of Build Orientation on Metallurgical and Mechanical Properties of Additively Manufactured Ti-6Al-4V Alloy

Effect of Build Orientation on Metallurgical and Mechanical Properties of Additively Manufactured Ti-6Al-4V Alloy

The Effect of Infill Angle and Build Orientation on the Impact Strength and Production Time of Porous Infill Structure

In developing a lightweight structure, the density of the structure can be reduced by converting a solid structure to a porous infill structure. Previous research has investigated that a triangular infill structure has the highest impact strength compared to other infill patterns. However, the impact strength of this structure may still be improved by adjusting other parameters without extending the production time. This research goal is to investigate the effect of the build orientation and infill angle on the impact strength and the production time of the triangular infill structure. To achieve that goal, this research uses a 3D printing process to manufacture a triangular infill structure made of Polylactic Acid. Seven levels of infill angle and two levels of build orientation are used to find the effect. In this experiment, twenty-six Charpy Impact specimens are printed using the Fused Deposition Modelling machine. Each specimen is printed according to ISO 179 standards and tested using a GT-7045 impact testing machine to measure the impact strength of the specimen. The results of this experiment indicate that the resistance of the on-edge build orientation to the impact load is better than the flat build orientation. The on-edge build orientation type requires less printing time compared to the flat build orientation type for each infill angle. The use of a 45-degree infill angle exhibits the highest impact resistance. To achieve the shortest printing time, the 0-degree infill angle is recommended.

Effect of heat treatment and defects on the tensile behavior of a hot work tool steel manufactured by laser powder bed fusion

AbstractMicrostructure and tensile properties of a hot work tool steel manufactured via laser powder bed fusion (LPBF) were investigated. Specimens were built under two different orientations and subjected to two quenching and tempering heat treatments, featuring different austenitizing and tempering temperatures and the eventual presence of a sub‐zero step. Microstructural analyses revealed a homogeneous tempered martensite structure after both heat treatments, with the only distinction of a higher alloying segregation at a sub micrometric scale length in samples subjected to the highest tempering temperatures. Hardness and tensile tests indicated a negligible effect of building orientation on mechanical properties, but a significant influence of heat treatment parameters. The treatment featuring the lower tempering temperatures and the sub‐zero step resulted in higher hardness, tensile strength, and elongation, attributed to a lower martensite tempering and alloying segregation. Tensile fracture occurred via crack initiation and unstable propagation from large LPBF defects in all the investigated conditions.

Effect of building orientation and fibre type on the mechanical behaviour of additively manufactured ABS matrix composites

ABSTRACT Additive manufacturing of fibre-reinforced composites show high potential for fabrication of next-generation lightweight complex structural parts. In this study, the effects of building orientation and fibre type, i.e. carbon fibre (CF), and glass fibre (GF), on the mechanical properties of acrylonitrile butadiene styrene (ABS) composites fabricated by fused deposition modelling (FDM) were investigated. The mechanical properties, namely, tensile strength, elastic modulus, hardness, and toughness, were analyzed for flat, on-edge, and upright building orientations. Results revealed that building orientation significantly influences several mechanical properties; in-plane (flat and on-edge) orientations produced the best mechanical properties, whereas upright orientations produced the worst. However, building orientation had little effect on material hardness. Further, compared to the elastic modulus and tensile strength of pure ABS, those of CF-reinforced ABS (CF–ABS) increased by 800% and 500%, respectively, and those of GF-reinforced ABS (GF–ABS) increased by 400% and 400%, respectively, proving that reinforcing ABS with either CF or GF improves the tensile properties. The impact energy of CF–ABS (0.5 J) was lower than that of GF–ABS (1.1 J) because of the brittleness of CF. Fracture surface analysis was performed via scanning electron microscopy (SEM) which gave insight to the nature and mode of fracture of the failed specimens. The most common defects on the printed specimens were void formation, fibre pullout, and poor bonding between fibre and matrix.

Influence of build orientation and aging on corrosion behaviour of 18Ni300 maraging steel produced via Powder Bed Fusion using Laser Beam (PBF-LB)

Conventional maraging steel corrodes uniformly but additive manufactured (AM) maraging steel can corrode differently, depending upon the angle of exposure of build layers to the corrosive media. The primary objective of this investigation is to examine the effect of build orientation and solution aging treatment (HT) on the corrosion behaviour of the AM maraging steel and to compare with that produced through the conventional route of casting and hot rolling. In this investigation, corrosion behaviour of maraging steel samples produced by Powder Bed Fusion using Laser Beam (PBF-LB), with different build orientations of 0°, 45°, and 90°, was investigated in a 3.5% NaCl solution. Corrosion resistance of the as-built (AB) samples was found to increase with decrease in the angle of inclination and related to structural heterogeneity and grain boundary density. However, corrosion resistance of the AB samples was decreased following heat treatment (solutioning and aging) and was controlled by precipitation of intermetallic phases and reversed austenite generation. While there was dominance of protective oxide layer of TiO2 in the AB and conventional sample, this oxide layer was not observed on the heat treated (HT) samples. Further, a marked difference was observed in pitting corrosion of the AB and HT samples.

Effect of build orientation on tribological and flexural properties of FDM-printed composite PLA parts

In the study, parts are fused deposition modeling–printed using polylactic acid filaments filled with copper, brass, bronze, tungsten, and carbon fiber. Wear and three-point bending tests are applied to FDM-printed specimens and it is yielded that on-edge oriented specimens had higher flexural strength while flat orientation contributed to wear resistance. Wear tracks are examined, and mostly abrasive wear is detected in the dry sliding condition while adhesive, fatigue and abrasive wear is observed in the wet sliding condition. Brass-filled polylactic acid specimens showed highest flexural strength and flexural modulus with 46.73 MPa and 1.53 GPa, respectively. Besides, the most wear resistant filler is determined as tungsten for dry and wet sliding conditions.