Efficient characterization of mechanical nonlinearity in triaxially braided composites by a novel unit cell

A range of nonlinear factors were investigated based on a novel unit cell model with a reduced domain to characterize the mechanical nonlinearity exhibited by braided composites in this study. These factors include geometric nonlinearity , nonlinear shear behaviour, plasticity within the matrix and transverse fibre direction, as well as failure and damage evolution. This novel size-reduced unit cell for braided composites, based on non-orthogonal translational symmetry principles, has been developed to streamline the analysis and tackle convergence challenges. This novel size-reduced unit cell is formulated by leveraging geometric features , as well as the symmetry and anti-symmetry of relative displacement boundary conditions . In order to evaluate the efficacy of these unit cells in characterizing elastic and strength properties , a benchmark study was conducted. The results demonstrate that the novel size-reduced unit cell has the ability to reliably predict the stiffness and strength responses of the 2D3A braided composite at the mesoscale . The unit cell’s predictions, which include nonlinear stress–strain curves, modulus, and strength, exhibit a robust analytical performance and a satisfactory agreement with experimental results.