Analysis of mechanical properties of lattice structures with stochastic geometric defects in additive manufacturing

Abstract

The lattice structure manufactured by additive manufacturing has geometric defects, which makes geometric shapes different from initial design. This research aims to incorporate stochastic geometric defects into the strut elements of a lattice structure to enhance predictive capabilities of simulation and analyze the influence of difference defects on mechanical properties. Here, X-ray computed tomography (CT) was used to extract the shape and distribution of process-induced defects. The X-ray CT images showed more geometric defects in horizontal struts than diagonal struts or vertical struts. Then, the geometric defects which are strut thickness variation and strut waviness were statistically quantified and considered into the ideal finite element model (FEM) to create the statistical FEM. Comparing the ideal FEM with the statistical FEM, it turns out that the statistical FEM was closer to experimental results. In addition, influence of different geometric defects in different struts on mechanical properties of the lattices were investigated. It indicated that strut thickness variation had more significant effect than strut waviness and thickness variation of diagonal strut had the greatest influence in difference direction.