Shear Behavior of Glass-Reinforced Systems at Low Temperatures

Abstract

Uniaxially reinforced composites exhibit nonlinear load displacements when loaded in shear, even at very low temperatures. The nonlinearity can be attributed to both elastic and plastic deformation. Information on nonlinear and plastic strain can be obtained by closely analyzing data from low-temperature shear tests. This paper describes the nonlinear elastic and plastic deformation resulting from solid-rod torsion tests at low temperatures. Nonlinear elastic and plastic strain was measured as a function of shear stress to detect the onset of irreversible deformation. At both 77 and 4 K, nonlinear strain measurements also showed finite strain differences among various composite materials, including unique strain variations of different epoxy resin systems. A third-order stress-strain relationship for predicting yield strength was investigated.