Computational modelling of strut defects in SLM manufactured lattice structures

Abstract

Addition of manufacturing defects to computational models of 3D-printed lattice structures enable improved simulation accuracy. A computational model of a cellular structure based on finite element method (FEM) analysis, often starts from defect-free computer-aided design (CAD) geometries to generate discretised meshes. Such idealised CAD geometries neglect imperfections, which occur during the additive manufacturing process of lattice structures, resulting in model oversimplification. This research aims to incorporate manufacturing defects in the strut elements of a lattice structure, thereby enhancing predictive capabilities of models. In this work, a method of generating CAD AM representative strut models is proposed. The models are generated from micro-computer tomography (μCT) analysis of SLM fabricated struts. The proposed additive manufacturing (AM) representative strut FE model's axial stiffness and critical buckling load is compared to idealised- and μCT- based FE models, with significant error reduction over idealised strut models. The AM representative strut models are then used to generate full lattice FE models and compared with manufactured and idealised FE models. The AM representative FE lattice models show greater correlations toward experiment and more realistic deformation behaviours. Overall, the methodology used in this study demonstrates a novel approach to representing struts in FE models of AM fabricated lattice structures.