Dynamic Characterization of Compliant Materials Using an All Polymeric Split Hopkinson Bar

High strain rate response of engineered plastics and synthetic foams are becoming increasingly relevant and important for the design and development of automobile exterior and interior systems. The Split Hopkinson Bar (SHB) technique has been routinely used for measuring high strain rate properties of high strength materials. Attempts to use this technique to determine the high strain rate behavior of compliant materials, such as plastics, rubbers, and foams, suffer from limitations on the maximum achievable strain and from high noise-to-signal ratios. In this paper an All Polymeric Split Hopkinson Bar (APSHB) is introduced, which overcomes these limitations. Polymeric pressure bars have a closer impedance match between the pressure bars and specimen materials, thus providing both a low noise-to-signal ratio data, and a longer input stress pulse for maximum achievable strains exceeding 100%. The strain gage data are analyzed incorporating viscoelastic behavior of the polymeric pressure bars. High strain rate (10² s^-1- 2×10³ s^-1) compression data on Polycarbonate, elastomer, and polyurethane foam are presented.