用比值法计算非对称循环加载下金属材料的疲劳损伤

Using specific value method to calculate fatigue damage of metallic materials under unsymmetric cycled loading

提出了在非对称循环加载下,描述金属材料弹塑性材料行为的损伤演变速率方程式和各个历程与不同损伤量Doi相对应寿命Noi的估算式,其方法是采用以塑性应变幅同弹性应变幅的比值Δεp/Δεe作为载荷参量,以常用的材料常数作为材料参数。新计算式计算结果与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、方便工程应用、节约人力、时间和资金有着实际意义。

Under an unsymmetric cyclic loading,the damage evolution rate equations for describing the behaviour of metallic materials and elastoplastic materials and the evaluation formulae of life N oi corresponding to different amount of damage D oi in every course have been advanced.Its method is regarding the specific value Δ ε p /Δ ε e of plastic strain range to elastic strain range as the load parameter,and taking the commonly used material constant for the parameter of material.The result of calculation are identical with the result calculated by Landgraf's equation,and the calculating precision is more rigorous.This will make practical significance upon the avoidance of excessive and repeated fatigue tests,the convenionce of engineering application and the economization on manpower,time and fund.