【摘要】 实际工程中的结构件往往具有多个不确定因素,包括材料、几何、载荷等。这些不确定因素导致构件的局部应力应变响应和疲劳寿命响应具有随机性。因此对低周疲劳分析中的局部应力应变法进行了概率分析。通过基本随机变量将诺伯法中的循环应力应变曲线(迟滞回线)和诺伯公式表示为概率曲线,基本随机变量反映了构件的不确定因素。通过建立近似拟合多项式的方法,求得局部应力应变的随机响应。将应变寿命曲线视为概率曲线,采用随机累积损伤理论,通过同样方法得到疲劳寿命的随机响应。算例表明结果与蒙特卡罗模拟的结果十分接近。该方法是一个简单有效的疲劳寿命概率分析方法。更多还原

【Abstract】 The components in practical engineering are always of uncertainties from material, geometry, loading, etc. The uncertainties result in the randomness of local stress, local strain and fatigue life. In this paper the probabilistic analysis of local stress and strain in low cycle fatigue is performed. The cycle stress-strain response (hysteresis loops) and the Neuber formula are both treated as probabilistic curves with random variables in Neuber method. The uncertainties of material, geometry, loading, etc., are characterized by random variables. Polynomials are constructed to evaluate the random local stress and local strain. The cyclic strain-life relation is treated as probabilistic curve. In the same way, the random characteristic value of fatigue life is obtained with the random theory of fatigue damage accumulation. An example is given. It is shown that the results in the example are agreeable to those from Monte Corlo simulation, indicating that the present method is simple and efficient.更多还原