Influence of layer architecture and constituent selection on the quasi-static and cyclic fracture mechanical behavior of metallic laminate materials.

从实验文献中得知，定义界面处的材料不均匀效应可以对层合金属复合材料的疲劳寿命产生积极的影响。另一方面，现有的数值模型可以定量地预测不同性质界面附近裂纹尖端驱动力的分叉、分层和屏蔽效应。然而，目前还不可能预测界面不同性质对层合板循环裂纹扩展的影响，因此，本研究的总体目标是研究界面不同性质对循环加载和准静态加载下金属层合板断裂力学行为的不同影响，并确定相应的材料体系、层合板结构和加载侧影响因素以及相关的损伤机制。此外，LMC界面增韧机制对损伤过程的影响将通过独特的GK-REM的现场实验来确定。在此基础上，建立了考虑各影响变量对断裂力学行为影响的交叉材料解析模型。基于该模型，将推导出断裂力学优化的层合板设计，并随后制造和研究以验证该模型，重点是不同性能与层合板结构之间的相互作用。除了界面处的强度梯度和弹性模量梯度的影响外，还将系统地研究层状结构的变化，如界面密度和层厚度对断裂力学行为的影响。为了研究界面上不同性能的影响，采用ARB工艺专门制造不同的LMC和双金属，然后在准静态或循环加载下研究它们的断裂力学性能。这使得可以单独或结合地详细了解影响断裂力学行为的变量，并由此得出优化的材料设计。

It is known from experimental literature that defined material inhomogeneity effects at interfaces can have a positive effect on the fatigue life of laminated metallic composites (LMCs). On the other hand, existing numerical models can quantitatively predict crack bifurcation, delamination and shielding effects of the crack tip driving force near individual interfaces with dissimilar properties. However, it is currently not possible to predict the effects of dissimilar properties at interfaces on cyclic crack propagation in LMCs, based on which a quantitative fracture mechanics model description could be derived.Therefore, the overall objective of this research project is to investigate the different effects of dissimilar properties at interfaces on the fracture mechanical behavior under cyclic as well as under quasi-static loading and to identify the corresponding material system-, laminate architecture- and loading-side influencing factors as well as associated damage mechanisms of metallic laminates. In addition, the effects of toughening mechanisms at interfaces in LMCs on the damage processes will be identified by means of in-situ experiments in the unique GK-REM. On this basis, an analytical cross-material model is to be developed that takes into account the synergetic interaction of the various influencing variables on the fracture mechanical behavior. Based on this model, a fracture-mechanically optimized laminate design will be derived and subsequently manufactured and investigated to validate the model.The focus is on the interaction of dissimilar properties with the lamellar architecture. The influences of the variation of the lamellar architecture, such as the interfacial density and the layer thickness, on the fracture mechanical behavior will be systematically investigated in addition to the effects of strength gradients and gradients in the elastic modulus at the interfaces. In order to investigate the influence of the dissimilar properties at the interfaces, different LMCs and bimetals are to be specifically produced by means of the ARB process, which are then investigated under a quasi-static or cyclic loading with regard to their fracture mechanical properties. This makes it possible to understand the influencing variables on the fracture-mechanical behavior in detail, both in isolation and in combination with each other, and to derive an optimized material design from this.