Mechanical properties of an epoxy-based adhesive under high strain rate loadings at low temperature environment

The tensile properties of an epoxy-based adhesive subject to high strain rate loadings at low temperatures were studied. Tensile split Hopkinson bar incorporating with an environmental chamber was utilized to conduct tensile property tests. Mechanical Parameters, like strength, Young's Modulus, strain to failure and fracture energy at low temperatures (−20°C and −40 °C) with different strain rates were investigated. The results show that at room temperature (RT), the strength and stiffness both increase significantly with the increase of strain rate. However, the increment of strength at low temperatures is insignificant. Interestingly, at RT and −20 °C, strain to failure increase with the increase of strain rates. From the stress-strain curves, strain softening phenomenon at high strain rates are observed at RT and −20 °C.This could be explained by the localized temperature rise in the specimens when the strain rate reaches high. At −40 °C, strain to failure decreases with the increase of strain rate and strain softening disappears. The larger temperature difference between the environment and the localized temperature rise in the specimens may reduce the strain softening phenomenon. Effects of high strain rate on tensile properties of epoxy adhesive at low temperatures are different from that on polyurethane-based adhesive in the literature.