• CN:11-2187/TH
  • ISSN:0577-6686

›› 2001, Vol. 37 ›› Issue (11): 1-6.

• 论文 •    下一篇

应变疲劳可靠性分析的现状及展望

赵永翔   

  1. 西南交通大学机械工程研究所
  • 发布日期:2001-11-15

ON THE STRAIN-BASED FATIGUE RELIABILITY ANALYSIS

Zhao Yongxiang   

  1. Southwest Jiaotong University
  • Published:2001-11-15

摘要: 未来是应用塑性变形知识解决结构失效问题的时代,应变疲劳可靠性分析是其中重要问题之一,它在90年代才引起注意,文献很少。现有方法假设Coffin-Manson循环应变—寿命(CSL)关系中的疲劳强度和塑性系数为独立随机变量,强度和塑性指数为常数,实际上它们都是拟合试验数据的相关随机变量。因此,只适于缺乏试验数据时的近似分析。试验揭示了材料的循环应力一应变(CSS)响应存在很大分散性。考虑这一分散性和CSL与CSS关系中材料常数的相关性,建立新的方法是未来值得研究的基础课题。建立考虑平均应变/应力影响和多轴方法,使之应用于工程实践是值得进一步研究的重要课题。

关键词: 可靠性, 疲劳, 平均应变/应力效应, 随机循环应力—应变响应, 应变分析

Abstract: It is coming of age to apply the fundamental knowledge of plastic deformation dealing various failures of engineering structures. One of topical problems is issue of strain-based fatigue reliability analysis to consider the intrinsic scattering of fatigue damage. Up to now, limited studies have been made in this issue since 1990s. They all almost derived their approaches by assuming that the fatigue strength and ductile coefficients are independent random variables and the fatigue strength and ductile exponents are constants in the Coffin-Manson cyclic strain-life (CSL) relation. Actually, these material constants should be dependent random variables coming from fits of test CSL data by the relation. Therefore, the existent approaches are only feasible for the approximation when the test data are not available. In addition, a worthy note problem is the random cyclic stress – strain (CSS) responses of engineering material revealed by Zhao et al’s experiment. A fundamental forward project is to establish a strain-based method, which can take into account the random responses and treat the material constants in the CSL and CSS relations as dependent random variables. On basis of this method, an important further forward project is to extrapolate the method into the cases of non-symmetrical and multi-axial CSS conditions to be suitable for engineering practice.

Key words: Fatigue, Mean strain/stress effect, Random cyclic stress-strain responses, Reliability, Strain analysis

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