Compression behavior of lattice structures produced by selective laser melting: X-ray tomography based experimental and finite element approaches

The compression behavior of hollow architectured structures obtained by additive manufacturing was investigated in this work. Two face-centered cubic structures with the same shape and repetitive pattern but different struts and nodes thicknesses were produced using the selective laser melting (SLM)technique. Deformation of the structures under compression was imaged by in-situ and ex-situ X-ray tomography scanning. The initial state of the structure was scanned using the stitching tomography method to capture detailed 3D images illustrating both the macroscopic hollow structure and local microporosity in the nodes and struts. A 3D image-based conformal finite element model was then built for the simulation of the compression test using Gurson-Tvergaard-Needleman (GTN) porous plasticity and a new procedure allowing to inform the local porosity of each element directly from high resolution tomography. Simulations considering a homogeneous matrix with an average initial porosity everywhere were compared to the new heterogeneous model. A fairly good agreement was found between the heterogeneous model and experiments especially in the prediction of fracture location