Experimental and numerical investigation of very high cycle fatigue of high performance fibre-reinforced plastics

该项目研究了玻璃纤维增强塑料和碳纤维增强塑料在超过10 E +8载荷循环的高循环次数下的疲劳行为。已经开发了两种不同的测试概念，现在可用于综合测试系列。一个概念是基于共振激励;第二个原则是利用4点弯曲测试。这两个概念结合了几个在线监测技术来分析疲劳过程（热成像，模态退化，显微镜，刚度退化的测量）。该项目的主要目的是全面调查低应力水平下的疲劳现象，从而实现长寿命周期。合作伙伴的目标是合理的损伤参数，这些参数是可测量的，适用于理论考虑。实验策略是首先分析简单层合板（单向，交叉铺层）的机理。然后，这些知识将被转移，并用于表征平衡的多层层压板的疲劳。此外，特殊的VHCF相关的影响，如裂纹萌生在开始和裂纹停止在疲劳寿命后期将进行检查。同时，开发了一种理论方法，用于模拟疲劳过程和寿命周期评估。

The project investigates the fatigue behavior of glass fiber-reinforced plastics and carbon fiber-reinforced plastics at very high cycle numbers beyond 10E+8 load cycles. Two different test concepts have been developed and are now available for comprehensive test series. One concept is based on a resonance excitation; the second principle utilizes a 4-point-bending test. Both concepts are combined with several online monitoring techniques to analyze the fatigue process (thermography, modal degradation, microscopy, measurement of stiffness degradation). The primary aim of the project is the comprehensive investigation of the fatigue phenomena at low stress levels leading to a long life cycle. The partners aim for reasonable damage parameters which are gaugeable and applicable for theoretical considerations. The experimental strategy is to firstly analyze the mechanisms of simple laminates (unidirectional, cross ply). Then, this knowledge will be transferred and used to characterize the fatigue of balanced multi-layer laminates. Additionally, special VHCF-relevant effects such as crack initiation in the beginning and crack arrest in the late fatigue life will be examined. In parallel, a theoretical approach is developed for simulating the fatigue process and for life cycle assessment.