An analytical constitutive model for progressive damage analysis of three‐dimensional braided composites

This study investigates the progressive damage behavior of three‐dimensional (3D) braided composites using a new analytical constitutive model. The composite microstructure is represented by yarns and an out‐of‐yarn matrix. The progressive damage behavior of yarns is modeled by a 3D Linde failure criterion, and that of the out‐of‐yarn matrix is modeled by an extended Drucker–Prager criterion. A bridging model is used to establish stress and strain relations between fiber and polymer matrix. Thus, the constitutive model of 3D braided composites is developed in the form of a system of analytical equations, and a numerical solution for the equation set is provided in this study. The elastic modulus, the strength constants, and the stress–strain behavior of 3D braided composites under tension and shear are computed by the model, and the results are consistent with the finite element results and the experimental data. The nonlinear damage behavior of 3D braided composites under unidirectional tension, compression, and shear is analyzed. The composite materials show repeated stiffness degradations during damage evolution because of successive failures of different compositions. Damage behavior depends significantly on the stress states and braiding structures of the composites. Braiding angle and fiber volume fraction mainly influence the mechanical properties of the composites, but barely affect the failure modes and tendencies of stress–strain curves. POLYM. COMPOS., 39:4188–4204, 2018. © 2017 Society of Plastics Engineers