抄録
Accumulation of microscopic damage, which occurs in fiber-diameter scale, causes failure of carbon fiberreinforced plastics. Therefore, accurate evaluation of microscopic damage is important to predict failure of structure made from composite materials. In this study, effect of macroscopic nonlinear behavior and failure criteria for prediction of initial matrix cracking are investigated using a multiscale approach which consists of macroscopic scale and microscopic scale analyses. On the macroscopic analysis, laminate is modeled as a homogeneous body, and comparison between elastic and elasto-plastic constitutive laws is performed to explore effect of nonlinear behavior on microscopic damage. On the microscopic analysis, the 3D periodic unit cell (PUC) analysis considering microscopic structure of the material is conducted using the strain history obtained from the macroscopic analysis as external force. The multiscale approach is applied to tensile tests of unidirectional laminates under off-axis loading, and initial cracking strains of each loading condition are predicted. Several failure criteria are employed for matrix resin in the PUC analysis, and are compared each other to reveal important factors of failure prediction in CFRP laminates. Comparison of stress states at failure shows that hydrostatic stress plays an important role in failure prediction.
