Computer modelling of residual stress & distortion for additively manufactured metal parts

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2022-11-28

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Polat, Yusuf Alptuğ

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Selective Laser Melting is a promising manufacturing technique which has been developed significantly in recent years. Additive nature of the process and selective fusion of metal powders enables manufacturing of complex geometries with minimum material wastege. However, residual stress formation during build stage of Selective Laser Melting process have negative effect on part mechanical properties and service life. Existence of residual stresses may lead to crack formation, part distortion and may reduce fatigue life eventually causing part failure. Although residual stress is released to some extent by post-process heat treatment, distortion occurs and allowable part tolerances may not be satisfied. For this reason, strong understanding of the mechanisms of residual stress and deformation is required in order to mitigate the detrimental effects of problems in question. Hovewer, the complex multiphysics characteristics of SLM process make it difficult to tailor the process parameters and overcome manufacturing issues; besides, long process time of the process and wastege of raw material make the experimental or trial-error solution approaches unfeasible. At this point numerical simulation techniques offer an applicable practice for the understanding, prediction and mitigation of residual stress and distoriton problem. In this study, modelling and simulation apporaches for residual stress and distortions for SLM process as well as subsequent heat treatment of 17-4 PH Stainless Steel are evaluated. Validation of simulation results are practiced with both CMM and contour residual stress measurement technique.

Subject Keywords

Additive manufacturing, Selective laser melting, Finite element method, Integrated computational materials engineering, Modelling & simulation, Residual stress & distortion

URI

https://hdl.handle.net/11511/101794

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

Y. A. Polat, “Computer modelling of residual stress & distortion for additively manufactured metal parts,” M.S. - Master of Science, Middle East Technical University, 2022.