Mechanical characterization of hyperelastic rubber materials used as protective layers for structures operating under high dynamic loading conditions

Abstract

This work proposes an original approach to determine the Mooney-Rivlin hyperelastic material model constants, thereby providing a better understanding of how rubber materials can be used as protective layers for structures operating under high dynamic loading conditions, such as impact or ballistic applications. The mechanical characteristics of two hyperelastic materials, SBR-65 rubber and PUR-85 rubber, with varying Shore hardness levels, have been analysed for the first time through quasi-static tensile and compression tests. Consequently, a set of dynamic compression tests has been conducted using a single-stage gas gun to study the mechanical behaviour of the two rubber materials at high-strain-rates and to formulate a dynamic model for numerical analysis using the finite element method. Dynamic stress-strain curves and associated dynamic mechanical parameters have been obtained for the two rubber materials. The experimental results indicate that hyperelasticity governs the mechanical properties of both materials, with notable variation in the dynamic response of rubber materials at high-strain-rates, revealing distinct time-dependent mechanical characteristics. At the same time, the study demonstrates that an increase in the Shore hardness of the rubber corresponds to an increase in the material’s yield stress. In a further step, a finite element analysis incorporating the Mooney-Rivlin constitutive model has been developed to simulate the mechanical response of hyperelastic materials under dynamic loading conditions. The numerical simulations closely match the experimental data, demonstrating the accuracy of the constitutive model in predicting the nonlinear mechanical behaviour of the two rubber materials under dynamic loading. This study also highlights the distinct functional roles of each material, showing that SBR-65 is well-suited as an energy-absorbing backing layer, while PUR-85 provides the stiffness and resistance required for use as a striking layer in ballistic protection systems.