Residual stiffness residual strength coupled model of composite laminates

A coupled model of residual stiffness-residual strength was presented under the assumption that the strength and stiffness of the laminates are degraded in fatigue process due to the same damage modes at the same time. A relationship between the damage defined by residual stiffness and that defined by residual strength was set up. The coupled model was validated by the experimental results of three kinds of laminates with different stacking sequences. The results show that the residual stiffness model and residual strength model presented in this paper are applicable to describe the stiffness and strength degradation rules. The strength degradation rule can be easily determined by only a few specimens based on this coupled model. And the parameter in the strength degradation model can be regarded as a material constant.