Modeling the transverse tensile and compressive failure behavior of triaxially braided composites

The complex failure behavior of triaxially braided composites under in-plane transverse load conditions is investigated through quasi-static experiments and meso-scale finite element (FE) simulations. A three-dimensional (3D) progressive damage model for the fiber tows is integrated with a cohesive model for the interfaces to simulate the initiation, accumulation and propagation behavior of damage in braided composites. The mesoscale FE model predicts well the global stress-strain responses, and the predicted strain distribution contours compare well with the experimental results captured by digital image correlation. The fully validated FE model is subsequently adopted to investigate the failure mechanism of a triaxially braided composite under transverse tensile and compressive loads. Numerical parametric studies are implemented to evaluate the effect of interface strength on the effective properties of the material and to identify the appropriate definition of through-thickness boundary conditions in the meso-FE simulation. The model presented in this study shows fairly good accuracy in predicting the failure behavior of a triaxially braided composite under different loadings, and it can be further employed to study the mechanical performance of similar materials.