Fracture and Fatigue of Alloys Under Mixed-Mode Loading

9420511 Hirth本研究探讨了混合模式加载对金属合金断裂和疲劳行为的影响。一种高纯度钢和一种特殊的铝合金，其基线数据已经存在，是研究的重点。机械性能测量包括在混合模式I-II-III型载荷下的低周疲劳和断裂测试，具有多轴和非比例载荷条件。用扫描电镜和透射电镜对试样的变形和断裂行为进行了表征。理论建模包括一个连续的位错建模的开始失败的形式，一个本地化的剪切变形的平移和弯曲不连续的倾斜墙。理论工作采用有限元建模的裂纹扩展的损伤机制与模式II和模式III加载组件。这项研究在材料设计标准中具有根本的重要性，因为它建立了混合模式I-II-III载荷下断裂韧性退化的机制。它还研究了低周疲劳下的损伤，这种负载的作用。***

9420511 Hirth This research examines mixed-mode loading effects on the fracture and fatigue behavior of metal alloys. A high purity steel and a special aluminum alloy, for which base-line data already exist, are the focus of the study. Mechanical property measurements include low-cycle fatigue and fracture tests under mixed mode type I-II-III loading, with multiaxial and non proportional loading conditions. Deformation and fracture behavior are characterized by scanning electron microscopy and transmission electron microscopy. Theoretical modeling includes a continuation of dislocation modeling of the onset of failure in the form of a localized shear deformation by a translating and bowing discontinuous tilt wall. Theoretical work employs finite element modeling of crack propagation in terms of a damage mechanism associated with the mode II and mode III loading components. %%% This research is of fundamental importance in material design standards since it establishes the mechanism of degradation of fracture toughness under mixed-mode I-II-III loading. It also examines the role of such loading on damage under low-cycle fatigue. ***