ISSN   1004-0595

CN  62-1224/O4

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近场动力学框架下钢轨疲劳裂纹萌生预测的数值方法研究

Numerical Method for Predicting Rail Fatigue Crack Initiation with Peridynamic Theory

  • 摘要: 经典连续介质力学在求解由裂纹引起的不连续问题时,会出现数学构架失效的情况. 为克服这一难题,基于近场动力学理论,构建铁路钢轨疲劳裂纹萌生的数值预测方法,可实现钢轨疲劳裂纹萌生寿命与位置的预测. 当未出现疲劳裂纹时,通过与经典连续介质力学模型的结果对比,验证近场动力学模型的正确性和适用性. 分析了车轮全滑动、黏着-滑动和无摩擦三种状态对钢轨疲劳裂纹萌生的影响规律,结果表明:车轮由全滑动向无摩擦转变的过程中,裂纹萌生位置由钢轨表层转移到内部,裂纹萌生所需的荷载循环次数由0.45×107次增至2.05×107次,可见车轮滚滑状态会影响裂纹的萌生位置,并且较大的切向接触应力会显著降低钢轨的疲劳裂纹萌生寿命.

     

    Abstract: The mathematical framework of classical continuum mechanics fails when sovling discontinuity problems caused by cracks. In order to overcome this problem, a numerical prediction method for rail fatigue crack initiation was proposed based on the peridynamic theory. The crack initiation life and position of the rail can be predicted using this method. When there were no fatigue cracks, the correctness and applicability of the peridynamic model were verified by comparison with the results of the classical continuum mechanical model. The effects of three wheel states including full sliding, stick-sliding and frictionless on the fatigue crack initiation of the rail were analyzed. The results showed that during the transition of the wheel state from full sliding to frictionless, the crack initiation position transferred from the surface of the rail to the interior, and the number of load cycles required for crack initiation increased from 0.45×107 to 2.05×107. It can be seen that the rolling-sliding states of the wheel affected the location of crack initiation, and the large tangential contact stress significantly reduced the fatigue crack initiation life of the rail.

     

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