An empirical strain rate-dependent constitutive relationship for glass-fibre reinforced epoxy and pure epoxy

Abstract

An investigation into the effect of strain rate on glass-fibre reinforced plastic (GFRP) and pure epoxy subjected to compressive loading has been conducted. Experimental results in this study were obtained by a hydraulically driven Instron Testing machine and a Split-Hopkinson Pressure Bar. The range of strain rates explored was between 5 × 10-4 sand 2500 s. A comparison between the behaviour of pure epoxy and GFRP reveals that both are strain rate sensitive, especially in the low strain rate regime. There is also a significant increase in the dynamic modulus as strain rate increases. It is shown that the stress-strain response under dynamic loading is not only a function of strain rate, but also of the strain state. An empirical equation incorporating both strain and strain rate terms is proposed and is found to adequately describe the stress-strain behaviour of both GFRP and pure epoxy for the range of loading rates studied. © 1995.