Prediction of Resin Region Strength Failure in Carbon Fiber Reinforced Composites

ABSTRACT Resin, as an isotropic material, has been the subject of extensive research on its damage mechanisms and failure criteria, evolving with the deepening investigation into the failure conditions of isotropic materials. However, traditional failure criteria based on the plastic/brittle dichotomy theory are insufficient to uniformly characterize the hydrostatic stress response and its regulatory effects under both tensile and compressive conditions. To address this limitation, the present study, grounded in the principle of stress invariants and fundamental energy concepts, proposes a failure criterion for homogeneous isotropic materials that distinguishes between tensile and compressive failure modes. The proposed criterion employs uniaxial tensile strength, compressive strength, and pure shear strength as the fundamental parameters, and experimental validation demonstrates its good consistency and high predictive accuracy. Moreover, tensile, compressive, and shear tests were conducted to obtain the mechanical properties of pure resin and T800/EC230R unidirectional composite laminates. By integrating the resin failure strength criterion under various temperature conditions, a progressive damage finite element method was employed to analyze the mechanical response of resin‐based composites under thermal loading. The results indicate that the proposed failure criterion achieves high accuracy in predicting structural strength, thereby providing a clear and comprehensive mathematical framework for the engineering design and theoretical analysis of composite materials.