Failure mechanism and size effect of new bioinspired sandwich under quasi-static load

A new additively manufactured bioinspired elytra-like interlocked sandwich (ABEIS) structure is fabricated using selective laser melting three-dimensional (3D)-printing technology. Six specimens of different sizes are designed. Flatwise compression (FC) and three-point bending (3 PB) quasi-static experiments are conducted. A corresponding finite-element model is established using Abaqus software. The Johnson-Cook constitutive model and fracture criteria are introduced. The damage parameters are obtained using dumbbell-shaped specimens. The test results indicate that the ABEIS has excellent mechanical performance, energy absorption, and designability. Analytical models under FC and 3 PB loads are established on the basis of the experimental results. The size effects are analyzed. Additionally, two-dimensional and 3D failure mechanism maps are obtained. Lastly, according to the maximum specific strength and minimum sandwich density, an optimization algorithm is designed for dual working conditions of compression and bending. The corresponding size ratios and specific strengths are determined for different density expectations.