Multi-Load Optimization of Support Structures for Minimizing Part Deformation in Laser Powder Bed Fusion

Abstract

Support structures act as primary conduits for heat flow in laser powder bed fusion (LPBF). Truss-type supports have proven to be a good choice for LPBF, with no metal powder entrapment and ease of removal. In this paper, we propose a framework for optimizing truss supports, subject to part deformation constraints.  In a typical LPBF build process, the supports evolve leading to time-varying thermal and structural loads.  Therefore, the proposed framework uses a multi-load strategy to optimize support. Equivalent structural loads (ESLs) are computed using the inherent strains induced at each deposition layer. Parts and supports are analyzed in tandem to compute the structural deformation at the end of each build layer. The optimal width of each support truss member is obtained through multi-load coupled optimization, subject to constraints on the nodal deformation to avoid recoater collision and desired geometric accuracy.  Numerical results demonstrate a reduction in part deformation when optimized supports are used.

Keywords: Laser powder bed fusion, truss support structures, optimization, part deformation, inherent strain