Damage of fibre reinforced plastics caused by the inner multiaxial stress state owing to thermal, hygrothermal and multiaxial mechanical loads

本研究建议的一般假设是，纤维增强塑料（FRP）的疲劳行为只受复合材料各层内的局部应力的影响。尽管这些局部应力可能有不同的原因，如机械负荷或温度和湿度的变化，但其影响-疲劳-仍然是可比的。因此，假定局部应力的原因不影响其效果。该项目旨在研究frp在机械、热和湿热载荷作用下的性能。根据研究假设，应进行广泛而完善的实验方案。所有的实验都集中在了解frp的逐渐损伤，这将在微观尺度上使用适当的测量系统来解决。不同的内部局部应力状态通过外部负载（多轴机械、热、湿热）的特定控制和组合以及使用不同堆叠顺序和层厚的各种层压板来再现。所有层压板都严格分为兴趣层和纯支撑层。作为实验的补充，分析和数值计算将确定材料内部的应力重新分布。由于项目的规模，必须有两个合作机构。

It is a general hypothesis of this research proposal that the fatigue behavior of fibre reinforced plastics (FRP) is exclusively influenced by local stresses within the individual layers of the composite. Although these local stresses may have different causes, such as mechanical loads or a change in temperature and humidity, the effect - fatigue - still is comparable. It is therefore assumed, that the cause of local stresses does not influence their effect. The project is to investigate the behavior of FRPs exposed to mechanical, thermal and hygrothermal loads. In accordance with the research hypothesis an extensive and well-tuned experimental program shall be conducted. All experiments focus on understanding gradual damaging of FRPs, which will be resolved on a microscale using adequate measuring systems. Different inner local stress states are reproduced by specific control and combination of outer loads (multiaxially mechanical, thermal, hygrothermal) and by the use of various laminates, which differ in stacking sequence and layer thickness. All laminates are strictly divided in layers of interest and purely supporting layers. Complementary to the experiments, analytical and numerical calculations will determine stress redistribution within the material. Due to the project s extent two collaborating institutes are mandatory.