微动疲劳裂纹萌生位置及形成方式研究

STUDY ON NUCLEATING LOCATION AND FORMATION OF FRETTING FATIGUE CRACKS

  • 摘要: 着重研究了微动桥足不同几何形状——方足(r = 0mm)及带不同半径r (0.3mm、0.6mm、0.9mm)对微动区接触应力的影响,用不同的r值模拟微动桥足在微动疲劳中的磨损状况。采用ANSYS有限元分析软件详细计算了接触表面的应力分布和磨损区、粘着区、滑动区及张开区的大小,进而讨论裂纹的萌生位置,并建立了不同的r大小即磨损状况与裂纹萌生位置的关系。同时针对方足微动桥/平面试件的接触几何,计算了不同名义接触压力分布形式对接触面上应力分布的影响。此外,还对方足微动桥/平面试件接触几何进行了三维有限元分析,证明了萌生裂纹通常是以多源方式同时出现。计算结果与实验结果吻合很好。

     

    Abstract: The influence of different geometry shapes of fretting-bridge foot (r = 0mm for rectangular and r = 0.3mm, 0.6mm, 0.9mm) on the distribution of contact stresses was mainly investigated. Using the different values of r to simulate the wear of the fretting-bridge foot, the distribution of contact stresses and the zone with wearing, sticking, sliding and opening on contact surface were calculated in details using finite element program ANSYS. After analyzing the nucleating locations of cracks, the relationship of different values of r, which represented wear, and nucleating locations of crack were established. For the contact geometry of a specimen contacting with a rectangular fretting bridge, the influence of distribution of nominal contact pressure on stresses of contact surface was also calculated. A three dimensional finite element method was used to analyze the contact stress distribution of a specimen contacting with a rectangular fretting bridge. The results show that several cracks usually nucleated simultaneously on the contact surface. The analysis results were in good agreement with the experimental ones.

     

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