An analytical model to predict back face deformation of hybrid soft body armors under ballistic impact

In the design of soft body armors for ballistic protection, the blunt trauma effect has to be taken into account and it is usually evaluated by the back face deformation (BFD). Most of the current research on blunt trauma is based on experiments and simulations, whereas the development of analytical models is still rare. This study develops an analytical model to predict BFD for a hybrid panel composed of modified aramid fabrics and Ultra-high molecular weight polyethylene (UHMWPE) unidirectional sheets, which is based on the two-stage damage evolution: shear plugging and tensile bulge. Firstly, the shear and tensile energy of the hybrid panel as well as the deformation energy of the clay were constructed. Secondly, the characteristic equations were developed according to the law of energy conservation and BFD could be obtained by solving the equations. The results of the analytical model were found to be in good agreement with experiments and FE simulations. With the assistance of the model, the effect of projectile geometry and optimized designs for hybrid panels have been studied.