Investigations into the mechanical properties of TA6V Dode-Thin lattice sandwich beams fabricated by powder bed laser beam melting process

Abstract

This paper compares the results of a theoretical approach, finite element analysis (FEA) and mechanical tests of monolithic TA6V Dode-Thin lattice core sandwich structures manufactured by powder bed laser beam melting process. An analytical approach to evaluate the mechanical properties of one Dode-Thin strut is briefly presented. The strut is then replaced by an equivalent beam whose cross-section is a solid circle. Various finite element (FE) models are used to calculate the effective mechanical properties of a defect-free structure and compared to the analytical results of beam theory. Besides the calculations, different experimental tests and measurements are carried out to measure the stiffness of the sandwich beams. These experiments show that both theoretical and numerical predictions significantly overestimate the stiffnesses. The discrepancies between the models and the as-built components are mainly due to geometrical imperfections and internal defects (porosity) caused by the AM process. Optical observations and X-ray computed tomography (CT) are then performed to determine the actual cross-sectional properties of the struts. Finally, this study provides the engineer with a simple method to replace a Dode-Thin strut with an equivalent beam of solid circular cross-section, and to define the equivalent 3D-orthotropic material with homogenized mechanical properties. Another contribution of this work is the insight into the as-built physical parameters to improve the correlation between models and experimental data.