The nonlinear mechanical behavior of plain woven composites under off-axis tension: A multiscale investigation considering yarn reorientation

The plain woven composites exhibit a nonlinear large deformation under off-axis tensile loading, which differs much from the linear elastic small deformation under axial tensile loading. In essence, the fiber yarns shall rotate to the load direction as the off-axis tensile force is applied. This paper is dedicated to attaining an in-depth understanding on the off-axis mechanical behavior of plain woven composites. To that end, a multiscale model that accounts for the fiber reorientation is developed. It couples the interactions among macroscopic structure, mesoscopic weave constitutive model and microscopic constituent failure mechanisms. The state variables are defined to trace the orientation of the fiber yarns and build the corresponding fiber yarn frames. The constitutive relations of yarns, incorporating in-plane shear nonlinearity, are established under the respective frames to ensure that the constitutive tensors are oriented along the fiber direction. In addition, the 3D digital image correlation technique is utilized to monitor the off-axis tensile test for the sake of validation. A good agreement is found between the multiscale model and the experimental test. The proposed multiscale model is expected to benefit further the structural design and optimization of plain woven composites under multiaxial complex loading.