Numerical simulations for composite structure with stress concentration (e.g.:hole, slit) have been conducted under simple loading (ex. tensile loading), but rarely have been conducted under combined loading. In this study, strength tests of plane specimen with a slit under combined loading (tension and shear) and observation were conducted. Furthermore, numerical simulations considering both in-plane and interlaminar failure were also conducted to investigate the failure mechanisms. Detail observation showed difference of failure mode according to loading pattern. Numerical simulations showed good agreement with failure mechanism. Furthermore, failure load was predicted in various loading patterns with practically sufficient accuracy by use of band broadening stress as compressive strength.
