Assessment of strut discontinuities in additively manufactured lattice structures using thermoelastic stress analysis

Additively manufactured lattice structures present several advantages to engineering applications through their lightweight properties and efficient load transfer pathways. Structural damage during fatigue loading to components with integrated lattices, however, can result in strut discontinuities that impede their mechanical properties. In-situ identification of discontinuities in lattice structures is necessary to ensure the robustness of structural performance. The assessment of such discontinuities can be difficult, whereby methods of optical analysis present a viable technique to evaluate structural behaviour. This work utilises thermoelastic stress analysis (TSA) as a method to rapidly identify strut discontinuities in lattice structures and assess the resultant alteration in load transfer pathways. TSA scans were performed on lattice tensile specimens under cyclic loading and calibrated using strain gauge rosettes, which were compared to numerical models obtained using the finite element (FE) method. Several lattice topologies were investigated with various tensile loading magnitudes to assess the applicability of the TSA method for several stress ranges and load transfer pathways. TSA was found to be an effective method for both qualitative and quantitative analyses of discontinuities in the lattice specimens, which agreed with the FE models. Furthermore, the TSA scans showed the change in load transfer pathways through stress redistribution, highlighting the evolution of critical lattice members and identifying potential failure sites. This approach of rapid stress assessment can be applied to the design and in situ failure analysis of lightweight aerospace and spacecraft structures under dynamic loading conditions.