scholarly journals Stable honeycomb structures and temperature based trajectory optimization for wire-arc additive manufacturing

2020 ◽  
Author(s):  
Martin Bähr ◽  
Johannes Buhl ◽  
Georg Radow ◽  
Johannes Schmidt ◽  
Markus Bambach ◽  
...  
Keyword(s):  
Additive Manufacturing ◽  
Trajectory Optimization ◽  
Tool Path ◽  
Honeycomb Structure ◽  
Mixed Integer ◽  
Voronoi Tesselation ◽  
Integer Linear Programming Problem ◽  
Mathematical Problems ◽  
Wire Arc Additive Manufacturing

Abstract We consider two mathematical problems that are connected and occur in the layer-wise production process of a workpiece using wire-arc additive manufacturing. As the first task, we consider the automatic construction of a honeycomb structure, given the boundary of a shape of interest. In doing this, we employ Lloyd’s algorithm in two different realizations. For computing the incorporated Voronoi tesselation we consider the use of a Delaunay triangulation or alternatively, the eikonal equation. We compare and modify these approaches with the aim of combining their respective advantages. Then in the second task, to find an optimal tool path guaranteeing minimal production time and high quality of the workpiece, a mixed-integer linear programming problem is derived. The model takes thermal conduction and radiation during the process into account and aims to minimize temperature gradients inside the material. Its solvability for standard mixed-integer solvers is demonstrated on several test-instances. The results are compared with manufactured workpieces.

scholarly journals DECOMPOSITION ALGORITHM FOR TOOL PATH PLANNING FOR WIRE-ARC ADDITIVE MANUFACTURING

2018 ◽  
Vol Vol.18 (No.1) ◽  
pp. 96-107 ◽  
Author(s):  
Lam NGUYEN ◽  
Johannes BUHL ◽  
Markus BAMBACH
Keyword(s):  
Additive Manufacturing ◽  
Path Planning ◽  
Computer Aided Design ◽  
Tool Path ◽  
Heuristic Method ◽  
Support Material ◽  
Build Time ◽  
Cad Models ◽  
Aided Design ◽  
Wire Arc Additive Manufacturing

Three-axis machines are limited in the production of geometrical features in powder-bed additive manufacturing processes. In case of overhangs, support material has to be added due to the nature of the process, which causes some disadvantages. Robot-based wire-arc additive manufacturing (WAAM) is able to fabricate overhangs without adding support material. Hence, build time, waste of material, and post-processing might be reduced considerably. In order to make full use of multi-axis advantages, slicing strategies are needed. To this end, the CAD (computer-aided design) model of the part to be built is first partitioned into sub-parts, and for each sub-part, an individual build direction is identified. Path planning for these sub-parts by slicing then enables to produce the parts. This study presents a heuristic method to deal with the decomposition of CAD models and build direction identification for sub-entities. The geometric data of two adjacent slices are analyzed to construct centroidal axes. These centroidal axes are used to navigate the slicing and building processes. A case study and experiments are presented to exemplify the algorithm.

scholarly journals Analysis of the Machining Process of Titanium Ti6Al-4V Parts Manufactured by Wire Arc Additive Manufacturing (WAAM)

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 766 ◽  
Author(s):  
Fernando Veiga ◽  
Alain Gil Del Val ◽  
Alfredo Suárez ◽  
Unai Alonso
Keyword(s):  
Additive Manufacturing ◽  
Arc Welding ◽  
Machine Tools ◽  
Optimal Strategies ◽  
Machining Process ◽  
Manufacturing Processes ◽  
Plasma Arc Welding ◽  
Traditional Manufacturing ◽  
Wire Arc Additive Manufacturing

In the current days, the new range of machine tools allows the production of titanium alloy parts for the aeronautical sector through additive technologies. The quality of the materials produced is being studied extensively by the research community. This new manufacturing paradigm also opens important challenges such as the definition and analysis of the optimal strategies for finishing-oriented machining in this type of part. Researchers in both materials and manufacturing processes are making numerous advances in this field. This article discusses the analysis of the production and subsequent machining in the quality of TI6Al4V produced by Wire Arc Additive Manufacturing (WAAM), more specifically Plasma Arc Welding (PAW). The promising results observed make it a viable alternative to traditional manufacturing methods.

scholarly journals Regional Control and Optimization of Heat Input during CMT by Wire Arc Additive Manufacturing: Modeling and Microstructure Effects

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1061
Author(s):  
Furong Chen ◽  
Yihang Yang ◽  
Hualong Feng
Keyword(s):  
Additive Manufacturing ◽  
Deposition Rate ◽  
Thermal History ◽  
Heat Input ◽  
Great Influence ◽  
Input Process ◽  
Cooling Process ◽  
Average Grain Size ◽  
Wire Arc Additive Manufacturing

Wire arc additive manufacturing (WAAM) of aluminum-magnesium (Al–Mg) ER5356 alloy deposits is accomplished by cold metal transfer (CMT). During the process, the temperature change of the alloy deposits has a great influence on molding quality, and the microstructure and properties of alloy deposits are also affected by the complex thermal history of the additive manufacturing process. Here, we used an inter-layer cooling process and controlled the heat input process to attempt to reduce the influence of thermal history on alloy deposits during the additive process. The results showed that inter-layer cooling can optimize the molding quality of alloy deposits, but with the disadvantages of a long test time and slow deposition rate. A simple and uniform reduction of heat input makes the molding quality worse, but controlling the heat input by regions can optimize the molding quality of the alloy deposits. The thermophysical properties of Al-Mg alloy deposits were measured, and we found that the specific heat capacity and thermal diffusivity of alloy deposits were not obviously affected by the temperature. The microstructure and morphology of the deposited specimens were observed and analyzed by microscope and electron back-scatter diffraction (EBSD). The process of controlled heat input results in a higher deposition rate, less side-wall roughness, minimum average grain size, and less coarse recrystallization. In addition, different thermal histories lead to different texture types in the inter-layer cooling process. Finally, a controlled heat input process yields the highest average microhardness of the deposited specimen, and the fluctuation range is small. We expect that the process of controlling heat input by model height region will be widely used in the WAAM field.

scholarly journals Towards Intelligent Monitoring System in Wire Arc Additive Manufacturing: A Surface Anomaly Detector on a Small Dataset

2021 ◽  
Author(s):  
Yuxing Li ◽  
Haocheng Mu ◽  
Joseph Polden ◽  
Huijun Li ◽  
Lei Wang ◽  
...  
Keyword(s):  
Image Processing ◽  
Additive Manufacturing ◽  
Monitoring System ◽  
Processing System ◽  
Image Processing System ◽  
Layer Deposition ◽  
Anomaly Detector ◽  
Precision Assessment ◽  
Wire Arc Additive Manufacturing

Abstract Rapid developments in artificial intelligence and image processing have presented many new opportunities for defect detection in manufacturing processes. In this work, an intelligent image processing system has been developed to monitor inter-layer deposition quality during a Wire Arc Additive Manufacturing (WAAM) process. Information produced from this system is to be used in conjunction with other quality monitoring systems to verify the quality of fabricated components. It is tailored to identify the presence of defects relating to lack-of-fusion and voids immediately after the deposition of a given layer. The image processing system is built upon the YOLOv3 architecture and through moderate changes on anchor settings, achieves 53% precision on surface anomaly detection and 100% accuracy in identifying the fabricated components’ location, providing a prerequisite for high precision assessment of welding quality. The work presented in this paper presents an inter-layer vision-based defect monitoring system in WAAM and serves to highlight the feasibility of developing such intelligent computer vision systems for monitoring the WAAM process for defects.

Novel Honeycomb Infill Fabrication Pattern for Additive Manufacturing

2019 ◽  
Author(s):  
AMM Nazmul Ahsan ◽  
Triston Ihrke ◽  
Bashir Khoda
Keyword(s):  
Additive Manufacturing ◽  
Tool Path ◽  
Physical Stability ◽  
Honeycomb Structure ◽  
Voxel Size ◽  
Compression Load ◽  
Build Time ◽  
Manufacturing Applications ◽  
Traditional Pattern ◽  
Traditional Counterpart

Abstract In additive manufacturing (AM), porous structures are often used as infills to reduce the build time and cost. However, providing physical stability to the skin and mechanical integrity to the object is a functional requirement for any infill pattern. Prismatic closed cells, i.e. honeycomb structure, are often used as infill in AM parts. These cells are periodic in nature and uniform in density. In this research, a new fabrication pattern for honeycomb infill is proposed for additive manufacturing applications. The proposed pattern can accommodate controllable variational honeycomb infill while maintaining continuity with relative ease. First, the honeycomb unit cell geometry is defined for uniform and non-uniform voxel size. A continuous tool-path is then designed to achieve the honeycomb structure. Finally, the structures are fabricated with the variational and uniform pattern and are then compared to the traditional pattern using compression testing. The results show that the proposed designs perform better under compression load and can absorb more energy compared to the traditional counterpart.

scholarly journals Energy-Efficient UAV Communication with Multiple GTs Based on Trajectory Optimization

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Yu Xu ◽  
Lin Xiao ◽  
Dingcheng Yang ◽  
Laurie Cuthbert ◽  
Yapeng Wang
Keyword(s):  
Trajectory Optimization ◽  
Low Cost ◽  
High Mobility ◽  
Optimization Techniques ◽  
Mixed Integer ◽  
Flight Trajectory ◽  
Special Cases ◽  
Standard Linear ◽  
Standard Linear Programming

Wireless communications with unmanned aerial vehicles (UAVs) is a promising technology offering potential high mobility and low cost. This paper studies a UAV-enabled communication system, in which a fixed-wing UAV is deployed to collect information from a group of distributed ground terminals (GTs). Considering the requirements for quality of service (QoS) (i.e., the throughput of each GT is above a given threshold) and GT scheduling, we maximize the energy efficiency (EE) of the UAV in bits/Joule by optimizing the UAV’s flight trajectory. In this paper, a mixed integer nonconvex optimization problem is formulated. As that is difficult to solve, we divide the formulated problem into two subproblems and apply standard linear programming (LP) and successive convex optimization techniques. We further propose an efficient iterative algorithm that jointly optimizes GT scheduling and the UAV’s trajectory. Moreover, we set two special cases as benchmarks to measure the performance of the proposed design. The numerical results show that our proposed design achieves much better performance than the other two benchmark designs.

scholarly journals A Multiaxis Tool Path Generation Approach for Thin Wall Structures Made with WAAM

2021 ◽  
Vol 5 (4) ◽  
pp. 128
Author(s):  
Matthieu Rauch ◽  
Jean-Yves Hascoet ◽  
Vincent Querard
Keyword(s):  
Additive Manufacturing ◽  
High Performance ◽  
Tool Path ◽  
Tool Path Generation ◽  
Path Generation ◽  
Thin Wall ◽  
Process Data ◽  
Technical Data ◽  
Wall Structures ◽  
Wire Arc Additive Manufacturing

Wire Arc Additive Manufacturing (WAAM) has emerged over the last decade and is dedicated to the realization of high-dimensional parts in various metallic materials. The usual process implementation consists in associating a high-performance welding generator as heat source, a NC controlled 6 or 8 degrees (for example) of freedom robotic arm as motion system and welding wire as feedstock. WAAM toolpath generation methods, although process specific, can be based on similar approaches developed for other processes, such as machining, to integrate the process data into a consistent technical data environment. This paper proposes a generic multiaxis tool path generation approach for thin wall structures made with WAAM. At first, the current technological and scientific challenges associated to CAD/CAM/CNC data chains for WAAM applications are introduced. The focus is on process planning aspects such as non-planar non-parallel slicing approaches and part orientation into the working space, and these are integrated in the proposed method. The interest of variable torch orientation control for complex shapes is proposed, and then, a new intersection crossing tool path method based on Design For Additive Manufacturing considerations is detailed. Eventually, two industrial use cases are introduced to highlight the interest of this approach for realizing large components.

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