Theoretical model for predicting stabbing resistance of soft body armor comprising fibrous composites

Soft body armor can effectively safeguard lives from stabbing attacks and they are mainly composed of fibrous composites. Currently, the evaluation of protective performance for soft body armor is mainly conducted by experiments or numerical simulations, with theoretical methods have been rarely mentioned. In this study, a spring-mass based theoretical model has been established to predict the stabbing resistant performance of a soft body armor comprising aramid with resin or unidirectional UHMWPE composites. The theoretical results agree well with the experimental results where the error in maximum impact force of the knife is within 3.2% and the displacement within 1.7%. The layers of penetration are also identical. By only inputting hardness and stiffness of the specimen, the theoretical model can efficiently provide the performance of a soft body armor composed of fiber composite material under different impact energy levels. With the aid of this theoretical model, one can optimize the composition of a soft body armor to achieve minimum weight and thickness in practical applications.