Topology optimization for considering distortion in additive manufacturing

This paper proposes a topology optimization method that takes account of distortion induced by additive manufacturing (AM). AM is a free-form manufacturing technique in which the part is built in a layer-by-layer manner. In particular, laser powder bed fusion (LPBF) is one of the most widespread technologies for metal parts. However, LPBF is known to cause residual stress and distortion during fabrication, which adversely affects the mechanical properties and dimensional accuracy of the part. Therefore, predicting and avoiding the residual stress and distortion are critical issues. Our goal is to propose a topology optimization method that considers distortion in AM and an analytical model of AM suitable for incorporation into topology optimization. First, we propose an analytical model of the AM building process by LPBF, and formulate an optimization problem. Next, a topological derivative of the objective functional is approximately derived using an adjoint variable method and is utilized to update the level set function via a time evolutionary reaction-diffusion equation. Finally, two-dimensional design examples demonstrate the validations and effectiveness of the proposed optimization methodology.

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