On the evaluation of in-situ mechanical properties of an additively manufactured BCC lattice

Additive manufacturing enables for fabrication of complex lattice materials with superior strength-to-weight ratios. These lattice structures are made from small struts that are difficult to test individually and whose responses may be size-dependent. In the present work, the mechanical response of a BCC lattice was studied when subjected to in-situ compression, i.e., monitored via Digital Volume Correlation (DVC). Backtracking was implemented in the DVC procedure to account for geometric imperfections generated by the manufacturing process. Displacement fields were measured via DVC and then employed in a Finite Element Model Updating (FEMU) procedure to calibrate the parameters of the constitutive law. Numerical simulations with the calibrated parameters were found to be in good agreement with experiments. The lattice material had a lower strength than that reported in the literature and measured with ex-situ tensile tests. This difference is attributed to size effects; this work demonstrates that they can be accounted for and that a single in-situ test is sufficient to calibrate such material properties.