Inter-Ply Slipping Behaviors and Kinetic Equation of Carbon Fiber-Reinforced Epoxy Prepregs for Hot Diaphragm Preforming

Wrinkles are urgent problems to be solved in the process of hot diaphragm preforming. Inter-ply slipping resistance is one of the causes of wrinkles. In this paper, based on the vertical inter-ply slipping test system, the inter-ply slipping behaviors of carbon fiber-reinforced epoxy resin composite prepregs were characterized. The mechanism of wrinkles caused by inter-ply slipping resistance was analyzed. According to the different characteristics expressed by the fiber and resin during the slip process, the inter-ply slipping behaviors of the prepregs were divided into three stages. The effect of temperature on the inter-ply slipping stresses was shown. The temperature will affect the viscosity of the prepregs. When the viscosity of the prepregs is low, the inter-ply slipping resistance will decrease. Based on the Coulomb friction law and the hydrodynamic equation, the inter-ply slipping kinetic equation of the prepregs was established. The inter-ply slipping kinetic equation was introduced into the ABAQUS main program by the 'vfriction' subroutine. The introduction of inter-ply slipping dynamics improved the accuracy of predicting the shape and position of wrinkles.