Generation of deposition paths and quadrilateral meshes in Additive Manufacturing

Wang Rui1*, Zhang Haiou1, Wang Guilan2, Tang Shangyong2, Li Runsheng1

1State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan 430074, PR China

2State Key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan 430074,PR China

Abstract

In wire arc welding Additive Manufacturing (WAAM), filling paths have a strong influence on the deformation of fabricated part. Many researchers employ FEM to analyze the effects of different filling strategies. However, they mainly majored in regular simple path (e.g. line and circle).This paper presents the method to generate meshes in deposition region of complicated path which can be used in FEM. First, the contour offset path and skeleton path is introduced. Then, the deposition region of each path is created by offsetting the paths inward and outward. Afterwards, quadrilateral meshes are constructed within each region. Deposition region is approximated by meshes. Keyword: deposition path, deposition region, quadrilateral meshes

Introduction

Additive Manufacturing (AM), or Rapid Prototyping (RP), has rapidly been developed in recent decades. Different from the traditional material subtract manufacturing method, it fabricates part layer by layer. In AM field, Wire and arc based Additive manufacturing has attracted more and more attention of researchers and institutions. Compared to AM with powder as feed stock material [Sing[1], Ding[2], Ding[3]] or laser as energy source [Ding[4]], the wire and arc AM has a lot of advantages, such as high material utilization, simple and inexpensive equipment and high production efficiency[Gu [5], Wang[6]]. The filling path plays an important role in AM process. It directly influences the geometric accuracy and mechanical property of fabricated part. There are two major basic filling patterns: raster scanning path and equal distance contour offset path [Ding D[7]]. Raster scanning path generation algorithm is very simple and efficient. But it scans in the same direction that would cause stress concentration leading to warping. Furthermore, the tool needs to cross the cavity frequently for part with holes. And the contour has a low accuracy because the raster path starts and ends in contour. Equal distance offset path generation algorithm iteratively offsets the outer contour of layer polygon by a fixed distance until filling the whole interior domain. This method change filling direction gradually (but still same in segment part) in each path which

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Reviewed Paper

can decrease stress concentration. Contrast to raster path, the offset path is continuous in contour that it can improve the surface accuracy. However, the contour offset algorithm is very complex and time consuming. G.Q. Jin [8] combines the two type of path. In the contour, the contour offset path is adopted to ensure the accuracy, and the zigzag raster path with the best slope degree is employed in the interior to achieve minimum manufacture time. Y Yang [9] gets the contour offset path through the interior recognition and complex self-intersection and sharp corner treatment. DS Kim [10] generates contour offset path based on Voronoi Diagram which do not needs self-intersection treatment. Y.Ding [Ding [11]] mapped the revolved overhanging structures to a plane base and filled the contours by offsetting the medial axis until the whole contour is covered. This method initially provided a solution for AM building overhanging structures in 8-axis system. Apart from the pattern of filling path, the deposition sequence determined by the paths also affects the part property in fabrication process. Sattari-Far I [12] studied the welding distortions in pipe-pipe joints of AISI stainless-steel type caused by different deposition sequence. A.H. Nickel [13] investigated two different deposition direction of raster pattern and two different deposition sequence of offset pattern. The FE analysis of four deposition sequence of multi-pass single-layer was performed by M P Mughal [14]. In the thermal analysis of welding process using FEM analysis software (e.g. ANSYS), the “birth and death” method is a key point because the activate order of elements represents the real deposition sequence. In many researches, only a few simple paths, such as segment, rectangle and circle, are considered and the activate order is decided manually. However, it is hard to do so for complex paths and elements.

Generation of deposition region

In production of complex thin wall parts, the wire arc welding additive manufacturing (WAAM) technology can substantially improve manufacturing efficiency. Contour offset paths, a common type of deposition path used in WAAM, are simple polygons derived from slice contours by inward offsetting. The method proposed in this study uses Voronoi diagram to create a contour offset path. For a given set of points and edges in a plane, a Voronoi diagram partitions the plane into regions, with each region including one point or one edge in its interior [Aurenhammer [15]]. These points and edges are called point sites or edge sites, and the regions are called Voronoi cells. For any point in a cell, its distance to the site associated with it is shorter than its distance to any other site. The boundaries of the Voronoi cells, i.e. the lines separating the regions, are referred to as Voronoi edges. For planar slice contours, sites are vertices and edges of polygons, and cell boundaries are made up of vertex angle bisectors, perpendiculars to edges at their endpoints, lines lying equidistant between parallel edges, and parabolas between points and segments. All line segments constituting the inner and outer contours offset within their own Voronoi cells and are joined to each other at their endpoints. This avoids dealing with

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contour intersections and self-intersections and thereby allows for efficient generation of a contour offset path based on Voronoi diagram. Figure 1 shows arbitrary slice contours. Figures 2 and 3 show the corresponding VD and contour offset path.

Fig.1. two slice contours

Fig.2. the Voronoi diagram of contours

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(a) all deposition paths (b) one of the deposition paths

(c) all deposition paths (d) one deposition path Fig.3. Deposition paths based on Voronoi diagram (purple outer polygons are

slice contours, the red&yellow inner polygons are deposition paths) In addition to contour offset path, skeleton is often extracted from VD as filling

paths, especially for a part whose wall thickness is smaller than the width of a single weld bead. The skeleton is a part of the Voronoi diagram. The algorithm proposed in this study provide two types of skeletons: skeleton derived from a single contour (bisectors of the edges in one polygon) and the skeleton derived from different contours (bisectors of edges in two polygons), as shown in Figure 4.

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Fig.4. skeleton (medium purple) and contours (black)

In WAAM, filling paths determine the position and sequence of energy input and

thus have a great influence on the deformation and stress state of fabricated part. The finite element method (FEM) is usually employed to analyze the distortion, temperature, and stress experienced a part during deposition. This method requires meshing of the real deposition region of the path. Deposition region refers to the ring-shaped region occupied by the material deposited from the melted wire. In this paper, a given deposition path is used as the input data, and the Voronoi algorithm is applied again to offset the path inward and outward separately, in the same manner as in the path generation process. Then two simple polygons are created as the outer and inner contours. The offset distance is half the effective width of a single deposition path, which depends on actual process parameters. Later, a bounding box is used to determine the inclusion relation between the outer and inner contours. The region enclosed by the two contours represents the effective deposition region. The vertices of the outer contour are ordered anti-clockwise, while those of the inner contour are ordered clockwise. Therefore, as the wire moves along the outer contour, the interior domain is on the left-hand side, while as the wire moves along the inner contour, the interior domain is on the right-hand side.

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Fig.5. Path (red polygon) and its deposition region contours (purple polygons)

As described above, the deposition region of a single path is defined by two

polygons whose shapes are similar to the path’s. The size of cells within the deposition region can be modified by adjusting the lengths of line segments during discretization of the region. In the method proposed in this study, offset polygons (including paths and the contours defining the deposition region) are constructed from line segments and arcs based on VD. The size of cells can be adjusted by discretization of line segments and arcs and specific parameters can be input by users.

The proposed method does not directly discretize the deposition region. Instead,

it discretizes the original path before offsetting so that discrete deposition contours can be naturally obtained after offsetting the path inward and outward. In addition, the arcs of the path need to be discretized into line segments. The purpose is to convert the path into a simpler polygon and thereby facilitate VD construction and path offsetting. Line segments can be discretized into several short segments with a given length or into a preset number of segments. Arcs can be discretized into segments with a given arc length or central angle. The vertices in the final discrete path are classified into three types: original vertices (0), points on line segments between their endpoints (1), and points on arcs between their endpoints (2). These vertices are denoted by V0, V1, or V2, with the integer identifiers (0, 1, and 2) indicating their attributes, i.e. types, as shown in the figure below.

0

0

0

1 11 2

22

Fig.6. Types of points (0 - end points of line segment or arc, 1 - points in line

segment, 2 - points in arc)

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After discretization of line segments and arcs, the discrete points on line segments between their endpoints automatically offset, generating discrete points on the line segments constituting the deposition contours. Most of the discrete points on the inner contour are paired with those on the outer contour. Then any two pairs of points on the contours can form a quadrangle. The resulting discrete points on the offset contours have the same attributes as their source points on the original path. These points are denoted by V0 or V1.

In the VD offset method, an arc will be generated when a convex vertex of a

polygon offsets outward or a concave vertex offsets inward. In this study, an offset arc can be generated by offsetting a vertex V0 or V2. An offset arc generated from a vertex V0 needs to be discretized; the length of the resulting segments depends on the discrete length or central angle of the arc. The two endpoints of the offset arc are designated V0 while other discrete points on it are designated V2. If an offset arc is derived from a vertex V2, it is just approximated by a line segment connecting its two endpoints, which are denoted by V2. As mentioned above, vertices V2 on the path are continuous and form arcs. Offsetting these arcs also produces arcs approximated by discrete segments. However, it is necessary to further discretize these arcs in order to obtain cells with desired sizes. Since these offset arcs are concentric with their source arcs on the path, the radius of each offset arc is its source arc’s radius plus the corresponding offset distance. The further discretization is also based on a preset arc length or central angle

The discretization of original path enables automatic generation of discrete

points on the contours during offsetting, thereby reducing the amount of calculation. Most quadrilateral cells in the mesh generated are obtained by combining triangles without complex calculation.

Fig.7. Discrete contours

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Quadrilateral mesh in deposition region

This section describes how to generate a finite element mesh in the effective

deposition region. A mesh normally comprises quadrangles, which are derived from triangles, and a small number of triangles. Based on the discrete polygons (offset contours), a Delaunay triangulation is constructed to mesh the polygons. The triangles in the triangulation share vertices with the polygons, as shown in the figure below.

Fig.8. Triangle meshes

Based on attributes of vertices, the triangles in a triangle mesh can be divided into several types as follows:

(1) For a triangle having vertices V1, V1, and V1, it is classified as T0 if the three

vertices lie on two contours; if they are distributed on the same contour, it is classified as T4;

(2) For a triangle having vertices V2, V2, and V2, it is classified as T1 if its vertices lie on two contours; if they are on the same contour, the triangle type is T5;

(3) For a triangle having vertices V0, V2, and V2, its type is T2 if its vertices are distributed on two contours; otherwise, its type is T6;

(4) Other triangles have their vertices coinciding with the vertices of the contours and link two line segments, or a line segment and an arc. These triangles are called link triangles and denoted by T3

Triangles T0, T1, T2, and T3 all have only two adjacent angles.

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0

0

2

3

3

Fig.9. triangle types

Next, triangles can be combined into quadrangles using the method below: (1) Randomly select a triangle with types T0, T1, and T2 as the start triangle.

Then set the start triangle as _current and set quadrilateral index, _qidx, as 0; (2) Traverse the adjacent triangles of _current, and store triangles T0, T1, T2, and

T3 that have not been visited in the candidate triangle container, _candidates; (3) If _candidates is empty, go to (8); (4) If the attribute of _current is T2, set _current as degenerate quadrangle and

store it in the mesh container. Then assign the quadrangle’s index to corresponding triangles.Set the current triangle as the combine triangle and go to (7);

(5) Each candidate triangle can combine with _current into a quadrangle. Find the quadrangle whose interior angles have the minimum standard error and then set the corresponding candidate triangle as _combine;

(6) If the attribute of _combine is different from that of _current, go to (4); otherwise, store this quadrangle in the mesh container;

(7) Traverse the adjacent triangles of _ combine and set a triangle T0, T1, T2, or T3 that has not been visited as the new _current. After that, go to (2); and

(8) Traverse unhandled triangles and find its adjacent quadrilateral. If the quadrilateral is a triangle (degenerate), directly merge it with this degenerated quadrilateral. If it is real quadrilateral, split the quadrilateral into a quadrangle and a triangle and then combine this two triangle (unhandled one and split one).

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for each triangle in triangles

classified triangles

START

If the type of unvisited triangle if 0,1,or 2

current = triangle

for each unvisited adjacent triangle of current

store triangle in candidates

If the type of triangle is 0,1,2 or 3

If candidates is empty

If type of current triangle is 2

store current in meshes for each triangle in candidates

select a suitable triangle as a combine triangle

If type of combine triangle is equal to type

of current triangle

merge combine and current to a quadrilateral, and store in the

meshes

set combine triangle to be current

YES

YES NO

NO

YES

YES

NO

for each unvisited adjacent triangle of combine triangle

If the type of triangle is 0,1,2 or 3

set the triangle as new current triangle

for each unvisited triangles

YES

NO

Merge the triangle into its adjacent quadrilateral END

Fig.10. Flowchart of generating meshes

Fig.11. Quadrilateral meshes (blue) and path

At last, the mesh cells are ordered based on sequence of points in the path, in

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order to ensure that the sequence of the cells is consistent with the deposition sequence. Therefore, in the FEM analysis, the activation sequence of elements can be determined easily without any calculation.

Conclusion

In this study, the contour offset path and skeleton path are created for the fabrication of thin wall part using WAAM technology. On the purpose of learning the deformation and stress distribution of part caused by the deposition path, the method of meshing in the real deposition region is introduced. The meshes in the deposition region mainly consist of quadrilateral meshes and also there exists little triangles sometimes. In the future work, the optimization of deposition path based on the FEM analysis is the primary aim.

References [1] Sing, Swee Leong, et al. "Laser and electron‐beam powder‐bed additive

manufacturing of metallic implants: A review on processes, materials and designs." Journal of Orthopaedic Research 34.3 (2016): 369-385.

[2] Ding, Yaoyu, James Warton, and Radovan Kovacevic. "Development of sensing and control system for robotized laser-based direct metal addition system." Additive Manufacturing 10 (2016): 24-35.

[3] Ding, Yaoyu, and Radovan Kovacevic. "Feasibility study on 3-d printing of metallic structural materials with robotized laser-based metal additive manufacturing." JOM 68.7 (2016): 1774-1779.

[4] Akbari, M., Ding, Y., & Kovacevic, R. (2017, June). Process Development for a Robotized Laser Wire Additive Manufacturing. In ASME 2017 12th International Manufacturing Science and Engineering Conference collocated with the JSME/ASME 2017 6th International Conference on Materials and Processing (pp. V002T01A015-V002T01A015). American Society of Mechanical Engineers.

[5] Jianglong Gu, Baoqiang Conga, Jialuo Dinga, et al. WIRE+ARC ADDITIVE MANUFACTURING OF ALUMINIUM [J].Solid Freeform Fabrication Proceedings, 2014.

[6] Wang F, Williams S, Colegrove P, et al. Microstructure and Mechanical Properties of Wire and Arc Additive Manufactured Ti-6Al-4V[J]. Metallurgical & Materials Transactions Part A, 2013, 44(2):968-977.

[7] Ding D, Pan Z, Cuiuri D, et al. A practical path planning methodology for wire and arc additive manufacturing of thin-walled structures[J]. Robotics and Computer-Integrated Manufacturing, 2015, 34(C):8-19.

[8] Jin G Q, Li W D, Gao L. An adaptive process planning approach of rapid prototyping and manufacturing[J]. Robotics and Computer-Integrated Manufacturing, 2013, 29(1):23-38.

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[9] Yang Y, Loh H T, Fuh J Y H, et al. Equidistant path generation for improving scanning efficiency in layered manufacturing[J]. Rapid Prototyping Journal, 2002, 8(1):30-37.

[10] Kim D S. Polygon offsetting using a Voronoi diagram and two stacks[J]. Computer-Aided Design, 1998, 30(14):1069-1076.

[11] Ding, Yaoyu, Rajeev Dwivedi, and Radovan Kovacevic. "Process planning for 8-axis robotized laser-based direct metal deposition system: A case on building revolved part." Robotics and Computer-Integrated Manufacturing 44 (2017): 67-76.

[12] Sattari-Far I, Javadi Y. Influence of welding sequence on welding distortions in pipes[J]. International Journal of Pressure Vessels & Piping, 2008, 85(4):265-274.

[13] Nickel A H, Barnett D M, Prinz F B. Thermal stresses and deposition patterns in layered manufacturing[J]. Materials Science & Engineering A, 2001, 317(1-2):59-64.

[14] Mughal M P, Mufti R A, Fawad H. The mechanical effects of deposition patterns in welding-based layered manufacturing[J]. Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture, 2007, 221(10):1499-1509.

[15] Aurenhammer F. Voronoi diagrams—a survey of a fundamental geometric data structure[C]// ACM COMPUTING SURVEYS. 1991:345-405.

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WelcomeTitle PagePrefaceOrganizing CommitteePapers to JournalsTable of ContentsMaterialsScanning Strategies in Electron Beam Melting to Influence Microstructure DevelopmentRelating Processing of Selective Laser Melted Structures to Their Material and Modal PropertiesThermal Property Measurement Methods and Analysis for Additive Manufacturing Solids and PowdersPrediction of Fatigue Lives in Additively Manufactured Alloys Based on the Crack-Growth ConceptFatigue Behavior of Additive Manufactured Parts in Different Process Chains – An Experimental StudyEffect of Process Parameter Variation on Microstructure and Mechanical Properties of Additively Manufactured Ti-6Al-4VOptimal Process Parameters for In Situ Alloyed Ti15Mo Structures by Laser Powder Bed FusionEfficient Fabrication of Ti6Al4V Alloy by Means of Multi-Laser Beam Selective Laser MeltingEffect of Heat Treatment and Hot Isostatic Pressing on the Morphology and Size of Pores in Additive Manufactured Ti-6Al-4V PartsEffect of Build 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Z Printing: A New Approach to Increasing 3D Printed Part StrengthA Mobile 3D Printer for Cooperative 3D PrintingA Floor Power Module for Cooperative 3D PrintingChanging Print Resolution on BAAM via Selectable NozzlesPredicting Sharkskin Instability in Extrusion Additive Manufacturing of Reinforced ThermoplasticsDesign of a Desktop Wire-Feed Prototyping MachineProcess Modeling and In-Situ Monitoring of Photopolymerization for Exposure Controlled Projection Lithography (ECPL)Effect of Constrained Surface Texturing on Separation Force in Projection StereolithographyModeling of Low One-Photon Polymerization for 3D Printing of UV-Curable SiliconesEffect of Process Parameters and Shot Peening on the Tensile Strength and Deflection of Polymer Parts Made Using Mask Image Projection Stereolithography (MIP-SLA)Additive Manufacturing Utilizing Stock Ultraviolet Curable SiliconeTemperature and Humidity Variation Effect on Process Behavior in Electrohydrodynamic Jet Printing of a Class of Optical AdhesivesReactive Inkjet Printing Approach towards 3D Silcione Elastomeric Structures FabricationMagnetohydrodynamic Drop-On-Demand Liquid Metal 3D PrintingSelective Separation Shaping of Polymeric PartsSelective Separation Shaping (SSS) – Large-Scale Fabrication PotentialsMechanical Properties of 304L Metal Parts Made by Laser-Foil-Printing ProcessInvestigation of Build Strategies for a Hybrid Manufacturing Process Progress on Ti-6Al-4VDirect Additive Subtractive Hybrid Manufacturing (DASH) – An Out of Envelope MethodMetallic Components Repair Strategies Using the Hybrid Manufacturing ProcessRapid Prototyping of EPS Pattern for Complicated Casting5-Axis Slicing Methods for Additive Manufacturing ProcessA Hybrid Method for Additive Manufacturing of Silicone StructuresAnalysis of Hybrid Manufacturing Systems Based on Additive Manufacturing TechnologyFabrication and Characterization of Ti6Al4V by Selective Electron Beam and Laser Hybrid MeltingDevelopment of a Hybrid Manufacturing Process for Precision Metal PartsDefects Classification of Laser Metal Deposition Using Acoustic Emission SensorAn Online Surface Defects Detection System for AWAM Based on Deep LearningDevelopment of Automatic Smoothing Station Based on Solvent Vapour Attack for Low Cost 3D PrintersCasting - Forging - Milling Composite Additive Manufacturing ThechnologyDesign and Development of a Multi-Tool Additive Manufacturing SystemChallenges in Making Complex Metal Large-Scale Parts for Additive Manufacturing: A Case Study Based on the Additive Manufacturing ExcavatorVisual Sensing and Image Processing for Error Detection in Laser Metal Wire Deposition

ApplicationsEmbedding of Liquids into Water Soluble Materials via Additive Manufacturing for Timed ReleasePrediction of the Elastic Response of TPMS Cellular Lattice Structures Using Finite Element MethodMultiscale Analysis of Cellular Solids Fabricated by EBMAn Investigation of Anisotropy of 3D Periodic Cellular Structure DesignsModeling of Crack Propagation in 2D Brittle Finite Lattice Structures Assisted by Additive ManufacturingEstimating Strength of Lattice Structure Using Material Extrusion Based on Deposition Modeling and Fracture MechanicsControlling Thermal Expansion with Lattice Structures Using Laser Powder Bed FusionDetermination of a Shape and Size Independent Material Modulus for Honeycomb Structures in Additive ManufacturingAdditively Manufactured Conformal Negative Stiffness HoneycombsA Framework for the Design of Biomimetic Cellular Materials for Additive ManufacturingA Post-Processing Procedure for Level Set Based Topology OptimizationMulti-Material Structural Topology Optimization under Uncertainty via a Stochastic Reduced Order Model ApproachTopology Optimization for 3D Material Distribution and Orientation in Additive ManufacturingTopological Optimization and Methodology for Fabricating Additively Manufactured Lightweight Metallic MirrorsTopology Optimization of an Additively Manufactured BeamQuantifying Accuracy of Metal Additive Processes through a Standardized Test ArtifactIntegrating Interactive Design and Simulation for Mass Customized 3D-Printed Objects – A Cup Holder ExampleHigh-Resolution Electrohydrodynamic Jet Printing of Molten Polycaprolactone3D Bioprinting of Scaffold Structure Using Micro-Extrusion TechnologyFracture Mechanism Analysis of Schoen Gyroid Cellular Structures Manufactured by Selective Laser MeltingAn Investigation of Build Orientation on Shrinkage in Sintered Bioceramic Parts Fabricated by Vat PhotopolymerizationHypervelocity Impact of Additively Manufactured A356/316L Interpenetrating Phase CompositesUnderstanding and Engineering of Natural Surfaces with Additive ManufacturingAdditive Fabrication of Polymer-Ceramic Composite for Bone Tissue EngineeringBinder Jet Additive Manufacturing of Stainless Steel - Tricalcium Phosphate Biocomposite for Bone Scaffold and Implant ApplicationsSelective Laser Melting of Novel Titanium-Tantalum Alloy as Orthopedic BiomaterialDevelopment of Virtual Surgical Planning Models and a Patient Specific Surgical Resection Guide for Treatment of a Distal Radius Osteosarcoma Using Medical 3D Modelling and Additive Manufacturing ProcessesDesign Optimisation of a Thermoplastic SplintReverse Engineering a Transhumeral Prosthetic Design for Additive ManufacturingBig Area Additive Manufacturing Application in Wind Turbine MoldsDesign, Fabrication, and Qualification of a 3D Printed Metal Quadruped Body: Combination Hydraulic Manifold, Structure and Mechanical InterfaceSmart Parts Fabrication Using Powder Bed Fusion Additive Manufacturing TechnologiesDesign for Protection: Systematic Approach to Prevent Product Piracy during Product Development Using AMThe Use of Electropolishing Surface Treatment on IN718 Parts Fabricated by Laser Powder Bed Fusion ProcessTowards Defect Detection in Metal SLM Parts Using Modal Analysis “Fingerprinting”Electrochemical Enhancement of the Surface Morphology and the Fatigue Performance of Ti-6Al-4V Parts Manufactured by Laser Beam MeltingFabrication of Metallic Multi-Material Components Using Laser Metal DepositionA Modified Inherent Strain Method for Fast Prediction of Residual Deformation in Additive Manufacturing of Metal Parts 2539Effects of Scanning Strategy on Residual Stress Formation in Additively Manufactured Ti-6Al-4V PartsHow Significant Is the Cost Impact of Part Consolidation within AM Adoption?Method for the Evaluation of Economic Efficiency of Additive and Conventional ManufacturingIntegrating AM into Existing Companies - Selection of Existing Parts for Increase of AcceptanceRamp-Up-Management in Additive Manufacturing – Technology Integration in Existing Business ProcessesRational Decision-Making for the Beneficial Application of Additive ManufacturingApproaching Rectangular Extrudate in 3D Printing for Building and Construction by Experimental Iteration of Nozzle DesignAreal Surface Characterization of Laser Sintered Parts for Various Process ParametersDesign and Process Considerations for Effective Additive Manufacturing of Heat ExchangersDesign and Additive Manufacturing of a Composite Crossflow Heat ExchangerFabrication and Quality Assessment of Thin Fins Built Using Metal Powder Bed Fusion Additive ManufacturingA Mobile Robot Gripper for Cooperative 3D PrintingTechnological Challenges for Automotive Series Production in Laser Beam MeltingQualification Challenges with Additive Manufacturing in Space ApplicationsMaterial Selection on Laser Sintered Stab Resistance Body ArmorInvestigation of Optical Coherence Tomography Imaging in Nylon 12 PowderPowder Bed Fusion Metrology for Additive Manufacturing Design GuidanceGeometrical Accuracy of Holes and Cylinders Manufactured with Fused Deposition ModelingNew Filament Deposition Technique for High Strength, Ductile 3D Printed PartsApplied Solvent-Based Slurry Stereolithography Process to Fabricate High-Performance Ceramic Earrings with Exquisite DetailsDesign and Preliminary Evaluation of a Deployable Mobile Makerspace for Informal Additive Manufacturing EducationComparative Costs of Additive Manufacturing vs. Machining: The Case Study of the Production of Forming Dies for Tube Bending

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