High strain rate response of epoxy in tensile and shear loading

Abstract

Epoxy type E-862 has been tested in tension and shear over a wide range of strain rates from 10 -4 to 700 s -1 . Experiments at strain rates of up to 2 s -1 have been conducted with a hydraulic testing machine, and tests at strain rates above 300 s -1 have been conducted using the split Hopkinson bar technique. The results show that the epoxy is very sensitive to the rate of deformation. A stiffer material response (increase in modulus) is observed with increasing strain rate in both tension and shear loadings. The maximum stress also increases with increasing strain rate. The maximum shear stress at a strain rate of 700 s -1 is roughly twice the maximum stress at a strain rate of 10 -4 s -1 . In the tensile tests a smaller increase in the maximum stress is observed. This, however, might be due to the existence of a hydrostatic stress component that causes a premature fracture of the specimens.