The Effect of Notch Constraint on Low-Cycle Fatigue

缺口约束对低周疲劳的影响

• 批准号: 8702110
• 负责人: William Sharpe
• 金额: $ 26.27万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-06-01 至 1990-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8702110&HistoricalAwards=false
• 关键词: Effect; Notch; Constraint; Low; Cycle

Modern technology requires that certain mechanical components (in air- breathing jet engines or nuclear reactors, for example) be subjected to a limited number of cycles at very high loading. Failures in these components begin at stress concentrations; however, very little is known about the effects of the constraint of the surrounding material on localized low-cycle fatigue. The objective of this research is to use a novel, realtime, interferometric strain measuring technique to begin to fill this gap. Strain will be measured over a very short gauge length at the root of stress concentrations for a variety of materials and loading conditions. The research will: evaluate the effect of constraints on the cyclic Neuber relation which is currently used in design of mechanical components; provide design guidance, on an empirical basis, which will permit a more intelligent estimate of the effects of the local stress/strain state on low-cycle fatigue; generate previously unobtainable data which will be valuable to those evaluating or developing theories for predicting localized cyclic behavior.

现代技术要求某些机械部件（例如喷气发动机或核反应堆）在非常高的负荷下进行有限次数的循环。这些部件的失效始于应力集中；然而，人们对周围材料约束对局部低周疲劳的影响知之甚少。本研究的目的是使用一种新颖的、实时的、干涉应变测量技术来填补这一空白。对于各种材料和加载条件，应变将在应力集中的根部测量很短的测量长度。研究将：评估约束对目前用于机械部件设计的循环Neuber关系的影响；在经验基础上提供设计指导，这将允许更智能地估计局部应力/应变状态对低周疲劳的影响；生成以前无法获得的数据，这些数据将对那些评估或发展预测局部循环行为的理论有价值。