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提出了在非对称循环加载下描述材料弹塑性材料行为的损伤演变速率方程式与各个历程与不同损伤量 Doi相对应的寿命 Noi估算式。其方法是采用以塑性应变幅同弹性应变幅之比值Δεp/Δεe 作为应力应变参量 ,以常用的材料常数作为材料参数。而且 ,还提出了与常用材料常数、平均应力与平均应变、加载临界历程长短有着函数关系的综合性材料常数的新概念。此外 ,以汽车的某一零件为例 ,计算了它的疲劳损伤。其计算结果与 Landgraf方程式计算结果一致 ,且计算精度较高。这对避免过多而重复的疲劳试验 ,对方便工程应用 ,对节约人力、时间和资金有着实际意义。
The damage evolution rate equation describing the behavior of the material elastoplastic under asymmetric cyclic loading and the Noi estimation formula of the life expectancy corresponding to different damage quantities Doi are proposed. The method uses the ratio of plastic strain amplitude to elastic strain amplitude, Δεp / Δεe, as the stress-strain parameter, and the commonly used material constant as the material parameter. In addition, a new concept of generalized material constants, which have a function relationship with the constants of common materials, average stress and average strain, and the critical length of loading, has also been proposed. In addition, a part of the car, for example, calculated its fatigue damage. The calculated results are consistent with the Landgraf equation and the calculation accuracy is high. This is to avoid excessive and repeated fatigue test, to facilitate engineering applications, to save manpower, time and money have practical significance.