Abstract
Bio-inspired cellular structures are being used for armor design for human safety. During highly dynamic phenomena such as impact and shock loading, these structures absorb energy by plastic deformation, hence minimizing injuries. Numerical approach employed for impact and ballistic simulations is well established for medium-range strain rates between 400 and 700 per second. However, under shock loading, the structure undergoes deformation with strain rates ranging 1000 to 5000 per second as it involves rampant interaction of shock waves with structures. For numerical modelling of such phenomenon, ConWep and MM-ALE simulation techniques are used effectively. In ConWep, the shock loads applied on structures are empirically derived and extrapolated from the experiment which is suited for higher scaled distances. The interaction between eulerian and lagrangian mesh is defined using MM-ALE approach by using FSI (Fluid-structure interaction) coupling. Intuitively, these methodology are stable for a far-field analysis but have shown inconsistency in predicting the behaviour for close to contact detonation scenarios. Current study investigates a deformable hybrid sandwich structure (such as cellular sandwich structures) subjected to such close-range scenario using non-cellular modelling techniques. The cellular structure is defined using an equivalent material model by implementing continuum orthotropic properties, considering lagrangian mesh to ameliorate the computational time. Hydrocodes based finite element scheme employed in LS-DYNA for investigating specific energy absorption (SEA) and force transmission through the structure during the deformation. Study aids in minimizing computational time and modelling complexities particularly in case of near-field detonation scenario. It is observed that the compression pattern in cellular structure is different for a near-field scenario when compared with the far-field scenarios.
