Inherent strain homogenization for fast residual deformation simulation of thin-walled lattice support structures built by laser powder bed fusion additive manufacturing

Abstract

Numerical simulation of residual deformation in metallic components with dense lattice support structures by the laser powder bed fusion (L-PBF) additive manufacturing process has been a significant challenge due to the very high computational expense in performing both finite element meshing and analysis. In this work, the modified inherent strain method is extended to enable efficient residual deformation simulation of l-PBF components with lattice support structures. The asymptotic homogenization method is employed to obtain the equivalent mechanical properties including the anisotropic elastic modulus and inherent strains given the topological configuration and laser scanning strategy of the thin-walled lattice support structures. A key finding is that the in-plane homogenized inherent strain values decrease with increasing volume density, which can be attributed to the directional dependence of inherent strains for the AM-processed material. Based on the homogenized mechanical properties and inherent strains, the thin-walled lattice support structures can be considered to be an effective solid continuum so that the simulation can be accelerated significantly to obtain residual deformation. Good accuracy of the homogenized mechanical property and inherent strains is validated by comparing the simulated residual deformation with experimental deformation measurement of several lattice structured beams of different volume densities. Efficiency of the proposed method is also demonstrated through numerical examples to have 80 % reduction in number of elements and nearly 10x speedup in computing time. In addition, the scalability of the proposed method is also verified through application to a complex L-PBF component fabricated with thin-walled support structures.