Department of Mechanical engineering
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Item A mold insert case study on topology optimized design for additive manufacturing(2019) Ranjan, RajitThe Additive Manufacturing (AM) of injection molding inserts has gained popularity during recent years primarily due to the reduced design-to-production time and form freedom offered by AM. In this paper, Topology Optimization (TO) is performed on a metallic mold insert which is to be produced by the Laser Powder Bed Fusion (LPBF) technique. First, a commercially available TO software is used, to minimize the mass of the component while ensuring adequate mechanical response under a prescribed loading condition. The commercial TO tool adopts geometry-based AM constraints and achieves a mass reduction of ~50 %. Furthermore, an in-house TO method has been developed which integrates a simplified AM process model within the standard TO algorithm for addressing the issue of local overheating during manufacturing. The two topology optimized designs are briefly compared, and the advantages of implemeItem A physics-based topology optimization method for enhancing precision in metal am parts(TU Delft, 2022) Ranjan, RajitA physics-based topology optimization method for enhancing precision in metal am parts | TU Delft Repository TU Delft Library search Press enter to search in title/abstract in title/abstract in authors local_library Repository Title Metadata Abstract Files A physics-based topology optimization method for enhancing precision in metal am parts Conference paper (2022) Authors R. Ranjan Computational Design and Mechanics - Mechanical, Maritime and Materials Engineering Zhuoer Chen Chalmers University of Technology C. Ayas Computational Design and Mechanics - Mechanical, Maritime and Materials Engineering M. Langelaar Computational Design and Mechanics - Mechanical, Maritime and Materials Engineering Matthijs Langelaar Computational Design and Mechanics - Mechanical, Maritime and Materials Engineering A. van Keulen Mechanical Engineering Research Group Computational DesignItem Overheating control in additive manufacturing using a 3D topology optimization method and experimental validation(Elsevier, 2023-01) Ranjan, RajitOverheating is a major issue especially in metal Additive Manufacturing (AM) processes, leading to poor surface quality, lack of dimensional precision, inferior performance and/or build failures. A 3D density-based topology optimization (TO) method is presented which addresses the issue of local overheating during metal AM. This is achieved by integrating a simplified AM thermal model and a thermal constraint within the optimization loop. The simplified model, recently presented in literature, offers significant computational gains while preserving the ability of overheating detection. The novel thermal constraint ensures that the overheating risk of optimized designs is reduced. This is fundamentally different from commonly used geometry-based TO methods which impose a geometric constraint on overhangs. Instead, the proposed approach takes the process physics into account. The proposed method is validated via an experimental comparative study. Optical tomography (OT) is used for in-situ monitoring of process conditions during fabrication and obtained data is used for evaluation of overheating tendencies. The novel TO method is compared with two other methods: standard TO and TO with geometric overhang control. The experimental data reveals that the novel physics-based TO design experienced less overheating during the build as compared to the two classical designs. A study further investigated the correlation between overheating observed by high OT values and the defect of porosity. It shows that overheated regions indeed show higher defect of porosity. This suggests that geometry-based guidelines, although enhance printability, may not be sufficient for eliminating overheating issues and related defects. Instead, the proposed physics-based method is able to deliver efficient designs with reduced risk of overheating.