Damage and failure of ductile metals under non-proportional loading paths: Experiments, modeling and numerical simulations

当前轻量化结构工程的发展对废旧材料提出了很高的要求。因此，详细了解它们的行为是必要的，以便能够在预期的载荷条件下对结构部件或复杂的创新轻质结构的载荷能力、安全性和使用寿命进行数值预测。在这种情况下，系统的研究与可重复的实验，特别是非比例加载路径覆盖所有相关的应力状态是必要的。因此，用平面双轴加载的金属试样进行实验，以便能够在不同的非比例加载条件下检测不同的损伤和破坏机制，以及在大范围的应力状态下直至最终断裂。此外，还将在微观层面上进行数值模拟，以确定无法通过实验确定的与应力状态和应力历史相关的参数。基于实验和数值结果，提出了一种连续损伤破坏模型，用于数值分析非比例加载条件下延性金属的变形和破坏行为。本研究项目的主要目标是建立一套具有非比例加载路径的双轴实验，用于在结构和航空工程或汽车工业等实际学科的安全性分析和使用寿命预测中检测不同应力历史的失效机制。

Current developments in lightweight structural engineering require high demands on used materials. Therefore, detailed knowledge of their behavior is necessary to be able to numerically predict loading capacity, safety and service life of structural components or complex innovative lightweight structures for expected loading conditions. In this context, systematic investigations with repeatable experiments especially for non-proportional loading paths covering all relevant stress states are necessary. Thus, experiments with flat biaxially loaded metal specimens will be performed to be able to detect different damage and failure mechanisms for different non-proportional loading conditions and for a wide range of stress states up to final fracture. Furthermore, numerical simulations on the micro-level will be carried out to develop parameters depending on the stress state and the stress history which cannot be determined by experiments. Based on experimental and numerical results a continuum damage and failure model will be proposed to numerically analyze the deformation and failure behavior of ductile metals under non-proportional loading conditions. Main goal of this research project is to establish a set of biaxial experiments with non-proportional loading paths used for detection of failure mechanisms for different stress histories in analysis of safety and service life prediction in practical disciplines like structural and aviation engineering or car industry.