Compression experiment and numerical evaluation on mechanical responses of the lattice structures with stochastic geometric defects originated from additive-manufacturing

Abstract The additive-manufacturing process generally fabricates lattices with geometries that depart from their as-designed counterparts and some inherent geometric imperfections exist within the fabricated lattice samples. In this paper, mechanical responses of the lattice structures with stochastic geometric defects originated from additive-manufacturing were examined. Here, X-ray Computed tomography (CT) was employed to capture the morphology and distribution of process-induced defects in order to study their role in the elastic response, damage initiation, and failure evolution under quasi-static compression. Testing results indicated that more geometric imperfections exist in the horizontal struts than in the diagonal or vertical struts. Then, extracted from the X-ray CT images, the process-induced defects (i.e. strut porosity, strut thickness variation and strut waviness) were introduced into the ideal finite element (FE) model for establishing the statistical FE model. A much more agreement is observed between the statistical FE model predicted results and experimental results. Finally, the roles of the single geometric defect on the mechanical responses and energy absorption of the lattices were investigated. It was indicated that strut thickness variation in the lattice structures has a larger impact in energy absorption than strut porosity or strut waviness.