Predicting strength of a unidirectional composite containing interface crack

Abstract

In this paper, both analytical Bridging Model and numerical GMC (Generalized Method of Cells) and HFGMC (High-Fidelity Generalized Method of Cells) are applied to analyze failures of a unidirectional (UD) composite with a cracked fiber and matrix interface. Interconnecting the internal stresses in the matrix with those in the fiber by a bridging tensor, the difference between Bridging Model and GMC/HFGMC is in the bridging tensors and the method of determining them. The stress concentration factors (SCFs) of the matrix in the composite before and after the cracked interface are calculated upon the different bridging tensors. Based on the true stresses resulted from the different bridging tensors and the SCFs, off-axial tensile strengths of UD composites are predicted. A total number of 9 different prediction schemes are made. The predicted results are compared with the experimental data of carbon, aramid, and flax fiber composites prepared and measured by ourselves. It is found that the predictions based on the Bridging Model equations provide overall the best agreement with the experiments.