Experimental analysis and numerical modelling of microcrack induced delaminations under cyclic loading with load reversals

该项目的目的是发展一个深刻的理解的损伤过程中的分层增长的纤维增强聚合物层压板（FRP）的基础上现有的内部纤维失效在循环加载与负载反转。通过对加载过程中相关损伤过程的分析和量化，阐明了载荷大小和方向对FRP层合板分层扩展的影响。在实验工作的基础上，详细的数值模拟的宏观和介观水平上开发的DCB和ENF的分层过程中，以及在层压板实验允许一个有目的的分析。因此，脱层长度相关的断裂模式，这不能通过实验实现的分析，是可能的。因此，分析了标准化裂纹扩展研究（DCB，ENF等）确定的特征值是否与标准化裂纹扩展研究（DCB，ENF等）确定的特征值一致。可以转移到嵌入层。此外，调查提供了大量的实验结果，在FRP层合板在面内载荷下的脱层过程，从而创建一个合适的分析和数值模型的发展的基础。它的研究在何种程度上现有的数值损伤模型（如内聚区的方法）允许可靠和有效的建模周期性分层增长和如何介观模拟结果可以用于宏观模拟的连续介质力学。

The aim of the project is to develop a profound understanding of the damage process during delamination growth in fibre-reinforced polymer laminates (FRP) based on existing inter fibre failures during cyclic loading with load reversals. By analysing and quantifying the relevant damage processes during loading, the influence of the level and direction of the applied load on delamination growth in FRP laminates is clarified. Based on the experimental work, detailed numerical simulations on a macro- and mesoscopic level are developed which allow a purposeful analysis of the delamination process in DCB- and ENF- as well as in laminate experiments. Thus, the delamination length-dependent analysis of the fracture modes, which cannot be implemented experimentally, is made possible. Consequently, it is analysed whether characteristic values determined by standardised crack propagation investigations (DCB, ENF etc.) can be transferred to embedded layers. In addition, the investigations provide extensive experimental results on the delamination process in FRP laminates under in-plane loading and thus create a basis for the development of suitable analytical and numerical models. It is investigated to what extent existing numerical damage models (e.g. cohesive zone approaches) allow reliable and efficient modelling of cyclic delamination growth and how the mesoscopic simulation results can be used for macroscopic simulations in terms of continuum mechanics.