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工程设计学报
Chinese Journal of Engineering Design  2010, Vol. 17 Issue (6): 435-438    DOI:
    
Prediction on probability distribution of fatigue life under spectrum loading
 WU   Ying, XIE  Li-Yang
School of Mechanical Engineering & Automation, Northeastern University, Shenyang 110819, China
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Abstract   In order to analyze fatigue life distribution under random loading, a new fatigue life distribution prediction model was established. Using rainflow method, the range and mean of random load were regarded as two random variables in two-dimensional fatigue load spectrum which was gained by rainflow method. Joint probability density function of two-variables was built up on the statistical analysis of load histories. Based on the definition of Miner cumulative damage theory, the causes of scattering of the cumulative damage were analyzed. The function of constant amplitude median Sa - Sm - N surface was established. According to statistical property analysis of Miner cumulative damage rule, probability distribution of fatigue life based on two-dimensional load spectrum was predicted. When the probability distribution of the cumulative damage was known, the fatigue life distribution could be predicted. Furthermore, component reliability at any pointed time could be available. In the end, an example of application was presented. The result shows that the above method is quite effective in prediction of the distribution of fatigue reliability analysis for engineering structures．

Key words： two-dimensional load spectrum      constant amplitude median Sa - Sm - N surface      Miner‘s rule      probability distribution of fatigue life     
Published: 28 December 2010
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WU Ying
XIE Li-Yang
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WU Ying, XIE Li-Yang. Prediction on probability distribution of fatigue life under spectrum loading. Chinese Journal of Engineering Design, 2010, 17(6): 435-438.

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https://www.zjujournals.com/gcsjxb/     OR     https://www.zjujournals.com/gcsjxb/Y2010/V17/I6/435


随机载荷作用下疲劳寿命分布预测模型

为了研究构件在随机载荷下的疲劳寿命分布,建立疲劳寿命分布预测模型.应用雨流计数法,将随机载荷-时间历程处理成以载荷幅值和均值为随机变量的二维联合概率密度函数,得到构件的二维疲劳载荷谱.从Miner累积损伤的定义出发,分析了累积损伤分散性的来源.以此为基础,通过建立等幅疲劳中值 Sa - Sm - N 曲面,提出了基于二维载荷谱的疲劳寿命分布预测模型,当累积损伤的概率分布已知时,可以估算出构件的疲劳寿命分布,进而得到零件在任一时刻的可靠度.最后,给出了一个具体应用实例.结果表明所提出的疲劳寿命分布预测方法具有较好的工程实用价值.

关键词： 二维疲劳载荷谱,  等幅中值 Sa - Sm - N 曲面,  Miner线性累积损伤准则,  疲劳寿命分布 
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