The consideration of realistic load assumptions is important for the fatigue design of highly stressed nodular cast iron components for wind energy application. Especially in case of overloads causing elastic–plastic deformation, residual stresses may have a strong impact on fatigue life. In strain-controlled fatigue tests with constant and variable amplitudes, the influence of overloads on lifetime was investigated. During fatigue testing, the transient material behavior, cyclic hardening, cyclic relaxation of the residual stresses, and quasi-static creep effects of the EN-GJS-400-18-LT was recorded and evaluated. To quantify the influence of the transient material behavior on the calculated lifetime, fatigue analyses are carried out with the strain-life approach, both with and without consideration of the transient material behavior. The results show that conservative damage sums are derived if the transient material behavior, especially the relaxation of tensile residual stresses, is neglected.

中文翻译：

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使用应变寿命方法在球墨铸铁疲劳评估中考虑变幅载荷下的瞬态材料行为

考虑实际载荷假设对于风能应用的高应力球墨铸铁部件的疲劳设计很重要。特别是在过载导致弹塑性变形的情况下，残余应力可能对疲劳寿命产生很大影响。在具有恒定和可变幅度的应变控制疲劳试验中，研究了过载对寿命的影响。在疲劳测试期间，记录和评估 EN-GJS-400-18-LT 的瞬态材料行为、循环硬化、残余应力的循环松弛和准静态蠕变效应。为了量化瞬态材料行为对计算寿命的影响，使用应变寿命方法进行疲劳分析，无论是否考虑瞬态材料行为。