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本文根据应力—强度干涉模型的基本原理,推导并建立起对构件(材料)疲劳寿命进行可靠性分析的计算公式,并将该公式的应用过程编制成计算机程序。构件上由随机载荷引起的应力分布是由实测的载荷—时间历程经雨流计数、统计分析后得到的。采用二维随机变量的概率密度函数来描述,以便使交变载荷的均值和幅值的变化特征都得到充分的反映。构件的疲劳强度分布是由材料疲劳强度试验的结果经统计处理后,用两条拟合曲线来描述的。一条是中值S-N曲线,它给定了强度分布的基本形态:另一条是描述试验结果分散程度的标准差随应力变化的关系曲线,它给定了疲劳强度的分布范围。作者对7C-503型拖车车架进行了室内快速模拟疲劳试验,以验证本文的计算结果,以及本文建立的分析构件(材料)疲劳寿命可靠性的计算公式和计算程序的正确、可行性。
Based on the basic principle of the stress-strength interference model, this paper deduces and establishes the calculation formula of the reliability analysis of the fatigue life of the component (material), and compiles the application process of the formula into the computer program. The stress distribution on the component caused by random load is calculated by the rain flow after the actual load-time history is calculated. The probability density function of a two-dimensional random variable is used to describe so that the mean and magnitude of the alternating load are fully reflected. The fatigue strength distribution of the components is calculated by the statistical test of the fatigue strength of the material and is described by two fitting curves. One is the median S-N curve, which gives the basic form of the intensity distribution: the other is the plot of the standard deviation of the degree of dispersion in the test results as a function of stress, which gives the distribution of fatigue strength. The author carried out fast simulation fatigue tests on 7C-503 trailer frame in order to verify the calculation results and the correctness and feasibility of the calculation formula and the calculation procedure of the fatigue life reliability of the component (material).