压力容器受低周疲劳裂纹萌生寿命的可靠性分析

由于压力容器构件的不确定因素,造成了构件局部应力应变响应和疲劳寿命具有随机性。通过将循环迟滞回线,应变寿命曲线表示为概率曲线,并考虑累积损伤的随机性,反映了构件的不确定性。使用Taylor多项式计算局部应力应变的均值和方差,并求出构件疲劳萌生寿命的均值和方差。计算了一定可靠性下的疲劳萌生寿命,得出在一定使用寿命时,结构的可靠度曲线。算例表明,它在疲劳寿命的可靠性估计中的应用及其工程意义。

Probability Analysis of Pressure Vessel's Crack Initiation Life due to Low Cycle Fatigue

The uncertainties of pressure vessel result in the randomness of local stress, local strain and fatigue life. Hysteresis loops and stress-strain are treated as probabilistic curves, random fatigue damage accumulation is also considered to demonstrate the uncertainty of the component. Taylor Polynomials are constructed to calculate the mean value and variance of local stress and local strain. The mean value and variance of component fatigue life is also obtained. The fatigue life under a certain reliability and the component reliability curve is gained. An example is given to show that the probabilistic method for local stress and strain has a good engineering significance in fatigue life analysis.