Ballistic Performance Prediction of Three-Layered Thermoplastic Laminates

This paper presents semi-empirical expressions for predicting the ballistic performance of three-layered thermoplastic laminates made up of polycarbonate (PC) and polymethyl methacrylate (PMMA) in closed forms, and also to verify the predictions by a series of ballistic impact tests. In the analysis, a normal impact of a steel ball projectile impinging on and passing through a three-layered laminate is described using an energy balance equation, from which semi-empirical expressions for predicting the residual velocity and the ballistic limit velocity are derived in the closed forms. The expression for the ballistic limit velocity thus obtained includes those of individual plates composing the laminate and interface coefficients depending on the layer structure and the bonding conditions between two adjacent plates. The predictions are verified by a series of ballistic impact tests carried out on the four kinds of three-layered laminates, and the effects of the stacking sequences and interfacial bonding conditions on the ballistic performance are examined