Understanding the critical role of boundary conditions in meso-scale finite element simulation of braided composites

A reasonable boundary condition for the meso-scale finite element (FE) simulation of textile composites is necessary for model validation against experiments, which is sometimes over-simplified for saving computation time. This paper examines the influence of boundary conditions on the global stress–strain response and deformation pattern, as well as the local damage and failure characters, through systematically comparison studies of numerical results against experimental results under different loading conditions. The results suggest that reasonable application of periodic boundary conditions can effectively improve the calculation efficiency, and the employment of symmetric boundary conditions along the loading direction will cause the undesired strain concentration and premature damage at the loading edges of the model. Besides, extra constraints along the thickness direction may restrain the normal out-of-plane deformation of the braided composites and thereby cause an overestimation of the transverse strengths. Graphical abstract: [Figure not available: see fulltext.].