A Failure Criterion Evaluation for Composite Materials

Recently research has been presented on the use of off-axis tensile tests which have nearly uniform stress states along the specimen gage lengths. The uniformity of the stress state is achieved by optimizing the amount of tab clamping and selectively locating the point about which the clamps rotate. The procedure uses the linear finite-element method. However, the off-axis specimens generally exhibit nonlinear response under axial loading. This nonlinear behavior herein is analytically approximated by applying the load incrementally. Predicted and experimentally determined responses of off-axis specimens are compared. To determine the load-carrying capacity of the specimens, a criterion which is a function of both stresses and strains is used.