A direct micromechanical approach toward the development of quadratic stress gradient failure criteria for textile composites

Based upon previous results of direct micromechanical method (DMM) analysis of the representative volume element (RVE) of a plain-weave textile composite, two methods for predicting failure envelopes are presented: a parametric ellipse-fitting scheme, and a 27-term quadratic stress-gradient failure criterion. Both include the consideration of micro level stress gradients and effectively predict failure in agreement with the DMM. The parametric ellipse-fitting method was found to agree with DMM results to within a few percent. The quadratic failure criterion was found to agree within 9.3%, but the method is more robust in its ability to predict failure for complex loading cases.