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.

在与实践相关的组件中使用的由纤维增强塑料（FRP）制成的复合材料在其使用寿命期间会承受各种静载荷和循环载荷。通常，作用在几何形状复杂的零部件上的载荷会产生不均匀的应力状态，这会对损伤的产生和传播产生不同的影响。该贡献集中在以弯曲试验为例的非均匀应力状态下疲劳损伤演化的数值模型。首先，扩展了基于有限元（FE）的疲劳损伤模型（FDM），以预测非均匀应力状态下的疲劳损伤演化。为了验证数值分析，开发了一种合适的弯曲装置来进行实验测试。为了产生复杂且不均匀的应力状态，将样品牢固地夹在两侧。其次，在不同的总应力比下进行了弯曲试验的实验研究和详细的有限元模拟。根据载荷循环的次数，可以通过数值方式（采用FDM）以及通过实验来获得弯曲试样的挠度演化。最后，仿真结果与实验结果的比较证明了扩展FDM作为工程工具的预测能力和适用性。