• CN：11-2187/TH
  • ISSN：0577-6686
机械工程学报

›› 2010, Vol. 46 ›› Issue (16): 119-124.

• 论文 • 上一篇    下一篇

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疲劳裂纹扩展中停留机制的考察

熊缨   

  1. 浙江工业大学机械工程学院;浙江工业大学特种装备制造与先进加工技术教育部重点实验室;浙江省特种装备制造与先进加工技术重点实验室
  • 发布日期:2010-08-20

Analysis of Crack Nonpropagation Behavior during Fatigue Crack Growth

XIONG Ying   

  1. College of Mechanical Engineering, Zhejiang University of Technology Key Laboratory of Special Purpose Equipment and Advanced Processing Technology of Ministry of Education, Zhejiang University of Technology Zhejiang Provincial Key Laboratory of Special Purpose Equipment and Advanced Processing Technology, Zhejiang University of Technology
  • Published:2010-08-20

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摘要： 采用高精度局部柔度测量技术，对结构钢SM400进行两种阶梯式变载条件下的疲劳试验，考察疲劳裂纹扩展中迟滞回线的形态变化与裂纹停留的关系。基于循环载荷中柔度变化与裂纹开闭口以及裂纹尖端附近应力分布的关系，讨论不同载荷方式下裂纹停留的形成机制。结果表明，裂纹停留意味着循环加载过程中裂纹尖端既不形成拉伸塑性区，也不形成压缩塑性区。疲劳裂纹停留在最大载荷时的裂纹形态有“裂尖锐型”和“裂尖钝型”。基于最大载荷和最小载荷后残留在裂纹表面的拉伸变形层确定载荷FRCPG和FRPG，能够获悉在最大和最小载荷时出现塑性区引起裂纹扩展的等价波形，可用于随机载荷波形的计数，为发展工程结构的剩余寿命预测提供一种理论依据。

关键词: 不扩展裂纹, 迟滞回线, 裂纹开闭口, 疲劳裂纹扩展, 柔度

Abstract: Fatigue crack propagation tests are carried out under two types of block loading amplitude using a high-precision local compliance measurement. Relationship between the shape change of hysteresis loops and the nonpropagating crack is studied. Based on relationships of compliance change, crack opening/closure phenomena and elastic-plastic behavior near the crack tip in a loading cycle, the mechanism of crack nonpropagation is investigated. It is shown that the profile of nonpropagating crack tip may be cuspate or obtuse at the maximum load. Crack nonpropagation means that there is no tension plastic zone and no compressive plastic zone generated at the crack tip. The loads FRCPG and FRPG are defined according to the residual tension deformation layer in a load cycle, and the equivalence waveforms of crack propagation induced by the crack tip plastic zone at the maximum and minimum loads can be known and used for counting random load waveforms, thus providing a theoretical basis for forecasting the residual life of engineering structure.

Key words: Compliance, Crack opening/closure, Fatigue crack growth, Hysteresis loop, Nonpropagating crack

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