A novel material degradation model for unidirectional CFRP composites

A novel material degradation model (MDM), which is an essential component of progressive damage models for failure analysis of composite structures, is proposed based on the representative volume element (RVE) method. In this model, a material degradation rule accounting for seven failure modes in a modified Hashin-type failure criterion is proposed. This rule determines the mechanical parameters that are degraded when a failure occurs. The degradation factors of these parameters are calculated from the RVE models for perfect and damaged materials corresponding to the seven failure modes, which are based on the fundamental properties of transverse isotropic fibers and isotropic matrix. To verify the proposed method, the calculated MDMs are used in the progressive failure analyses of open-hole laminates made of three types of CFRP composites under tensile and compressive loadings. Furthermore, the failure analyses of four kinds of double-lap single-bolted joint structures with various layups and geometry dimensions are also conducted under tensile loading. The numerical predictions of failure loads, failure patterns and load-displacement curves are compared to the experimental results. Good agreement between the model predictions and the experimental results demonstrates the effectiveness of the proposed MDM for the progressive damage analyses of open-hole laminates and composite bolted joints. (C) 2017 Elsevier Ltd. All rights reserved.