Finite element modelling of the compressive response of lattice structures manufactured using the selective laser melting technique

Previous work on lightweight energy-absorbing truss based structures has highlighted the potential of SLM-built lattices. Finite element models have been developed to predict the compressive response of lattice structures based on two simple architectures - a body-centred cubic structure (BCC) and a similar structure with vertical pillars (BCC-Z). Both 3D continuum and beam elements have been used to model the structures under quasi-static compressive loads. Key difficulties in modelling the lattice structures have been highlighted and possible solutions have been offered. The results from the FE models are compared to experimental data and have been shown to agree well. The collapse modes predicted by the FE models were also in agreement with the experimental observations. The stress distribution within the BCC unit cells at increasing levels of crush has been identified and shows the formation of plastic hinges in the struts near to the nodal regions. In the latter stages of this investigation, the unit cell geometry was modified in order to enhance the stiffness and yield stress under compressive loading conditions. Predictions made using both analytical and beam element FE models demonstrate that the stiffness and yield strength could be improved by varying the unit cell geometry. Further tests were carried out on modified lattice structures to verify the predictions.