Butterfly lattice materials for controllable multi-stage energy absorption

Energy absorption properties of cellular materials have gained increasing interest due to their superior performance and immense design space. This paper introduces a novel lattice material with a Butterfly configuration that has controllable multi-stage crushing behavior and high specific energy absorption capacity. A theoretical model is developed to predict the plateau stress, elastic modulus and critical strain of each stage, in order to obtain the multi-stage stress-strain curve. Compression experiments and the finite element modelling are also carried out to validate the theoretical model. Theoretical and experimental results show that the Butterfly lattice material has more than two crushing stages and a specific energy absorption property comparable to the traditional stretching-dominated lattice material. Finally, effects of topology configuration, cell number, and geometrical parameter on the energy absorption behavior are analyzed. It is found that the length of the vertical beam dramatically influences the plateau load and deformation behavior of each stage.