Abstract: A periodic cubic spline and corresponding calculate method are put forward for describing the tow path of 2D triaxial braided composites. Based on this spline, a method for solving the main material direction of tow element is obtained. The parametric curve of cross-section with asymmetrical lens-shape is created. And twist deformation of cross-section along the tow path is considered. Based on domain superposition method and cutting method, a finer and parameterized unit cell mesh model of 2D triaxial braided composites is obtained. An anisotropic damage model is built based on Murakami damage theory. The evolvement of damage model is controlled by equivalent displacements. For considering interface phase damage evolution, a unit cell model with interface phase is presented. The strength and the whole process of damage initiation, propagation and catastrophic failure of 2D triaxial braided composites with 45°braiding angle under axial or transverse tensile loading are simulated in detail. The predicted numerical results correlate well with the experimental results presented in the published literature.

Key words: 2D triaxial braided composites, domain superposition technique, progressive damage, strength prediction