A constituent-behavior-motivated model for damage in fiber reinforced composites

The aim of the work is to predict the onset and the progression of damage in the continuous fiber reinforced composite laminates taking into consideration the different mechanical behavior of the constituents in the composite under different loading conditions. The stresses in the constituents are obtained using a representative volume element (RVE) approach. Finite element analysis is carried out to extract the stresses in the constituents and the overall effective properties of the composite material. To consider the realistic behavior of the matrix of the composite material, a modified Drucker-Prager failure criterion is used. Direct test data on the individual constituents are used in this approach to model the failure of each of the constituents separately using the extracted stresses in the individual constituents. Failure envelope plotted for a unidirectional fiber reinforced composite material using the proposed model clearly shows that the initiation of damage is different in different constituents of the composite material. This is more realistic compared to the popularly used macroscopic criteria such as Tsai-Wu criterion. Propagation of failure in fiber reinforced composite is captured using a simple progressive damage model. It is also found that the hexagonal RVE has more predictive capabilities than the square RVE since the average distance between the fiber may play a major role in the strength prediction of composites.