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| Reliability analysis of fatigue propagation life for crack emanating from adjacent hole with non-normal random parameters |
| ZHANG Yan-Lin1, ZHANG Yi-Min1, ZHANG Yan-Fang2, JIN Ya-Juan1 |
| 1.School of Mechanical Engineering & Automation, Northeastern University, Shenyang 110004, China; 2.Department of Mathematics, Institute of Disaster Prevention Science and Technology, Sanhe 065201, China |
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Abstract Stress concentration often occurs along holes of mechanical components, and many cracks emanating from these holes. Predict crack propagation behavior emanating from these holes so as to assess the residual life and to avoid catastrophic failure. Because of geometrical dimensions, material properties and mechanical loads are often random variables; crack growth behavior is a random process. Probability fatigue is more meaningful to structural safety. Considering material properties and loads as non-normal random parameters, reliability analysis method of fatigue crack propagation life based on Paris-Endogan theory and maximum circumferential stress criterion was presented using stochastic finite element method, fourth moment method and Edgeworth series. Fatigue crack propagation life of a plate subjected to constant distributed stress at up & down edges with a crack emanating from a hole in the plate was analyzed. The crack path was simulated. From the results, the crack propagation rate at the initial stage is slow comparing with that at the final stage of crack growth. The reliability of crack propagation life and the residual strength of the plate are gradually decreasing along with the crack growth. The proposed method is meaningful to the reliability analysis for fatigue life of mechanical components.
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Published: 28 December 2010
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非正态参数圆孔间裂纹扩展寿命的可靠性分析
机械设备不可避免地存在许多圆孔结构,孔边是应力集中多发区域,许多裂纹发源于孔边,因此研究孔边裂纹扩展寿命对结构的疲劳寿命评定具有重要的实际意义.工程实际中结构尺寸、材料特性、载荷等因素常常具有不确定性,裂纹扩展过程是一个随机过程,研究随机裂纹扩展更加符合工程实际.以材料属性和载荷为随机变量,采用Paris-Erdogan 公式计算裂纹扩展寿命,裂纹扩展方向采用最大周向应力准则,在随机有限元法的基础上,结合计算可靠度的四阶矩法、Edgeworth级数展开,提出随机参数服从任意分布时的结构疲劳裂纹扩展寿命可靠度的计算方法.研究了参数服从任意分布时平板上两圆孔之间的疲劳裂纹扩展寿命可靠性相关问题,模拟了裂纹扩展路径,得到裂纹扩展寿命可靠度随裂纹扩展的变化趋势,从结果看出裂纹扩展速率不断加快，可靠度随着裂纹扩展逐渐降低，结构的剩余强度逐渐变小.新方法对孔边产生的裂纹扩展寿命可靠性分析具有一定的理论意义.
关键词：
疲劳寿命,
孔边裂纹,
非正态随机参数,
四阶矩法,
可靠性
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