Coupled Topology and Process Optimization in Powder Bed Fusion Additive Manufacturing
Published: 2024
Publication Name: Proceedings of SAMPE 2024
Publication URL: https://doi.org/10.33599/nasampe/s.24.0104
Abstract:
Large thermal-gradient additive manufacturing (AM) processes, such as powder bed fusion (PBF), exhibit process-dependent microstructures and properties that are not captured by traditional topology optimization (TO) design methods. The process-agnostic functionality of TO excludes valuable process-structure-property relationships from optimum design search and raises doubts about the validity of TO results when manufactured. This work addresses these shortcomings by implementing a coupled topology and process optimization algorithm for PBF AM. The algorithm augments a density-based TO search technique with the PBF process simulation model developed by AlphaSTAR Corporation to calculate as-solidified porosity. Mean porosity and volumetric energy density are utilized as objective criteria in a sequentially-coupled process optimization step that seeks optimum manufacturing parameters for a given TO solution. Isotropic elastic moduli are derived via a Mori-Tanaka homogenization scheme, and the resultant material property distribution is utilized to pose a new process-informed TO design problem. This procedure continues iteratively until discrepancies between as-designed and as-manufactured performance are minimized. For traditionally symmetric TO design solutions, the designs presented in this work are parameter-dependent and exhibit asymmetry in the build direction. Critically, a numerical comparison of process-agnostic and process-informed TO solutions shows performance improvements of up to 46 % achieved by the algorithm.