Bioinspired functionally graded gyroid sandwich panel subjected to impulsive loadings

Gradual and localised changes in mechanical properties can be achieved by functionally graded cellular structures with the aim to improve structural performance. Gyroid belongs to a class of cellular structures that naturally inspired continuous non-self-intersecting surfaces with controllable mechanical properties. In this work, dynamic compression on functionally graded gyroid and sandwich composite panels constructed from functionally graded gyroid core and metallic facets are numerically investigated and compared to evaluate the dynamic behaviours when subjected to extreme loadings. The Finite Element Analysis (FEA) is employed to characterises the deformation of proposed structures considering the rate-dependent properties, elastoplastic response and nonlinear contact. The Johnson-Cook model is utilised to capture the rate-dependent dynamic responses of the gyroid panels. The numerical model is then validated with experimental results under quasi-static compression. Owing to the symmetry, only a quarter of the gyroid panel is modelled using shell elements, which significantly reduces the computational cost. A series of studies are conducted to demonstrate the influences of different functionally graded cores on the blast resistances of gyroid composite panels. Reaction forces and critical stresses extracted from underneath protected structure are assessed. Gyroid sandwich structures clearly demonstrate unique dynamic crushing responses, impact energy mitigation & dissipation mechanisms, which leads to enhancement of the blast resistance