In-plane shear investigation of 3D surface-core braided composites

In-plane shear properties of three-dimensional (3D) surface-core braided composite are investigated by numerical simulation and experimental tests. Based on RVE models, the mechanical responses under in-plane shear load and the basic shear properties related to braiding parameters are predicted by using finite element method. Numerical results indicate that two groups of surface-cores possess distinct sensitivities to shear loads and identify the main load bearing components. In-plane shear tests are conducted to compare the effects of surface cuttings on the mechanical properties of present material and 3D 4-directional braided composite. The experimental data reveal that the cuttings degrade the shear moduli and strengths of the two materials to varying degrees. 3D surface-core braided composite can effectively restrain the decline of shear properties caused by cuttings. Scanning electron microscopy (SEM) is used to identify the distinct damage mechanisms of tested materials.