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试验揭示了核工程材料１Ｃｒ１８Ｎｉ９Ｔｉ不锈钢管道焊缝金属的循环应力─应变响应存在很大分散性。意味着任何外载，即使恒幅条件，将产生随机应变加载史。为保证设计分析的安全性，引入了称为“概率循环应力─应变曲线”的表征方法。应用线性回归技术和极大似然法原理，给出了概率曲线及其置信限的估计方法。以经过验证的良好假设分布──正态分布模拟循环应力幅的随机性。概率曲线表征为均值和均方差循环应力─应变幅曲线的形式。任意可靠度下的分析可方便地根据正态分布函数完成。材料低周疲劳试验结果分析说明了方法的有效性。
The experiment revealed that the cyclic stress-strain response of the weld metal of 1Cr18Ni9Ti stainless steel pipe for nuclear engineering material is very dispersive. Means any external load, even if the constant amplitude conditions, will have a random strain history. To ensure the safety of design analysis, a characterization method called “probability cyclic stress-strain curve” has been introduced. The linear regression technique and the principle of maximum likelihood method are used to estimate the probability curve and its confidence limits. Proven good distribution of hypotheses - the normal distribution simulates the randomness of cyclic stress amplitude. The probability curves are characterized as mean and mean square error cyclic stress-strain curves. Analysis at any level of reliability can easily be done using a normal distribution function. The analysis of low-cycle fatigue test results shows the effectiveness of the method.