A Direct Micromechanical Approach toward the Development of Quadratic Stress Gradient Failure Criteria for Textile Composites

ABSTRACT: 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. KEY WORDS: textile composites, strength, finite element analysis