Fracture and Fatigue of Alloys Under Mixed-Mode Loading

混合模式加载下合金的断裂和疲劳

• 批准号: 9420511
• 负责人: John Hirth
• 金额: --
• 依托单位: Washington State University
• 依托单位国家: 美国
• 项目类别: Continuing grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-04-15 至 1998-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9420511&HistoricalAwards=false
• 关键词: Fracture; Fatigue; Alloys; Under; Mixed

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. ***

[9420511] Hirth本研究考察了混合模式加载对金属合金断裂和疲劳行为的影响。研究的重点是一种高纯度的钢和一种特殊的铝合金，它们的基线数据已经存在。力学性能测量包括混合模式I-II-III型加载、多轴和非比例加载条件下的低周疲劳和断裂试验。通过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。理论建模包括以平移和弯曲的不连续倾斜壁的局部剪切变形的形式对破坏开始的位错建模的延续。理论工作采用了基于II型和III型加载构件损伤机制的裂纹扩展有限元模型。该研究建立了I-II-III混合模式加载下断裂韧性退化的机理，对材料设计标准具有基础性意义。它还研究了这种载荷在低周疲劳下对损伤的作用。＊＊＊