In order to study the law of mechanical component's reliability and sensitivity under the condition of load actting many times and reduce manufacturing costs by modifying component de-sign parameters according to the sensitivity ,a reliability model was built by combining the proba-bilistic perturbation method ,the moment method and considering the times of load acting .The reliability sensitivity of mechanical component with arbitrary distribution parameters on the con-dition of known first four moments of basic random variables was studied ,applying the probabi-listic perturbation method and the Edgeworth series technique ,combining the order statistic theo-ry to study the influence of load action time on the reliability and sensitivity calculation .Calcula-tion results of the reliability by this model were different from the traditional models .Consider-ing the times of load action ,the reliability values were different under different times of load ac-tion .A bolt was taken as an example to get the reliability variation with the increase in the times of loads .T he reliability and reliability sensitivities of the mean and variance of the random varia-bles were studied .The curves of reliabilities and sensitivities were obtained .Law with the role of the times of load action was that the reliability decreased as the times increased with a monotonic trend ,the reliability value was minimum when the times of load action was maximum . The curves of reliabilities of variables mean and variance had different trend .Among w hich the big-gest influence factor effect on the reliability with time was the diameter mean and variance of bolt .With the time increase ,the bolt cross-section diameter became the dominating factor affect the reliability of the bolt .%为了研究载荷多次作用时，机械零部件的可靠度及可靠性灵敏度变化规律，从灵敏度角度修改零件的设计参数，降低制造成本，建立一种可靠性模型结合了随机摄动法、Edgeworth级数技术，并考虑了载荷的作用次数。摄动法和Edgeworth级数可以在基本随机参数的前4阶矩已知的情况下，研究具有任意分布参数的机械零件的可靠性灵敏度设计问题，顺序统计量理论考虑了载荷作用次数在可靠度和灵敏度计算中的影响。使用这种模型计算出的可靠度会随着载荷作用次数而变化，这与静态的可靠度计算方法存在差别。以某一型号的螺栓为算例，应用此模型计算了其可靠度、随机变量均值和方差的可靠性灵敏度。由提出的方法得到了可靠度和可靠性灵敏度值及其随载荷作用次数变化的曲线。可靠度及可靠性灵敏度随载荷作用次数变化的规律是：载荷作用次数增加，可靠度值降低，变化趋势单调；载荷作用次数达到最大时，可靠度达到最小；随机变量均值和方差的灵敏度随载荷作用次数变化出现不同的变化趋势，其中螺栓截面直径的均值和方差灵敏度随载荷作用次数的变化最大，随作用次数的增加，螺栓截面直径的参数将对螺栓的可靠性起主要的决定作用。
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