On the Effect of the Cell Size and Beam Radius on the Compressive Strength and Residual Stresses of Ti-6Al-4V BCC Lattice Sandwich Structures Manufactured by L-PBF

Abstract

Lattice structures offer the possibility to obtain lightweight components with additional functionalities, improving their shock absorption and thermal exchange properties. Recently, a body-centered cubic (BCC) lattice structure has been used to fabricate metal lattice sandwich panels (MLSPs) for aerospace applications. MLSPs are made of two external skins and a lattice core and can be produced thanks to laser powder bed fusion technology (LPBF), which is characterized by its superior printing accuracy with respect to other additive manufacturing processes for metals. Since few studies can be found in the literature on Ti-6Al-4V MLSPs, further work is needed to evaluate the mechanical response of these panels. Moreover, due to their design complexity and to avoid a costly experimental campaign, numerical simulation could be used to encourage the industrial application of these structures. In this paper, different cell configurations were printed and tested in compression to study the influence of the cell’s geometrical parameters, i.e., the cell size and beam radius, on the mechanical response of MLSPs. Numerical simulations of the LPBF of these geometries were also carried out to understand how the residual stresses can be varied by varying the cell configuration. A geometrical evaluation was carried out to quantitatively express the influence of the beam radius and cell size on the resulting volume fraction, which strongly influences the mechanical behavior and residual stress profiles of MLSPs. From the analysis, we found that the C2-R0.35 sample resulted in the configuration with the highest compressive strength, while C3-R0.25 showed the lowest and most uniform residual stress profile.