Numerical modeling and experimental validation of fatigue damage in Cross-Ply CFRP composites under inhomogeneous stress states

Abstract

Composite materials made of fiber-reinforced plastics (FRPs) used in practice-relevant components are subjected to varying static and cyclic loads during their service life. In general, the loads acting on geometrically complex components generate inhomogeneous stress states, which have different effects on damage initiation and propagation. This contribution focuses on the numerical modeling of the fatigue damage evolution under inhomogeneous stress states using a bending test as an example. Firstly, a Finite-Element (FE) based Fatigue Damage Model (FDM) is extended for predicting the fatigue damage evolution under inhomogeneous stress states. To validate the numerical analysis, a suitable bending device is developed to perform experimental tests. In order to generate a complex and inhomogeneous stress state, the specimens are firmly clamped on both sides. Secondly, experimental investigations and detailed FE simulations of the bending tests are performed at different global stress ratios. Based on the number of load cycles, the deflection evolution of the bending specimens is obtained numerically (employing the FDM) as well as experimentally. Finally, the comparison of simulation results with experiments demonstrates the predictive capability and applicability of the extended FDM as an engineering tool.