A numerical method of fatigue life prediction of statically indeterminate truss structure based on gray model was established herein. This paper analyzed principles in dealing with the order of logarithm times, and determined right order of times to predict fatigue lifetime. Then it amended the definition of the critical parameters identifying failure elements, so that the choices of bounded parameters were more accurate. Before the search of main fatigue failure modes, this paper added the critical failure internal stress criterion, reducing the calculation of recognition algorithms for identifying failure modes. Based on the improved grey model(GM), it estimated the Weibull distribution function, and calculated different safe lifetimes of truss structure system under different reliability degrees. The numerical example of 10 truss structure shows the validity of the numerical method established. 

statically indeterminate truss structure, logarithm principle, grey model, Weibull distribution, fatigue life prediction

以超静定桁架结构为研究对象，提出了一种基于灰色预测模型（GM）的预测桁架结构疲劳寿命的数值方法。分析了对数阶次处理的原则，确定了适合桁架结构疲劳寿命预测的阶次;修正了临界失效元件识别参数的定义，使约界参数的选择更加精确;在主要疲劳失效模式搜寻前增加了临界失效内力判据，减小了识别失效模式算法的计算量;应用改进的灰色预测模型估计威布尔分布函数，预测出不同可靠度下的桁架结构疲劳安全寿命。所提供的十杆桁架结构的算例证明了该数值方法的有效性。

 

超静定桁架结构, 对数准则, 灰色预测模型, 威布尔分布, 疲劳寿命预测