In this paper, the low‐cycle fatigue characteristics of cold‐drawn steel were investigated under strain‐controlled uniaxial fatigue load. Cyclic softening was observed throughout fatigue life except for the initial relatively short period which exhibited cyclic hardening. Positive mean stress was found under fully reversed strain loading, indicating that there was a significant cyclic asymmetry. A modified local stress–strain method was proposed to estimate fatigue life of notched tension‐compression asymmetric material. In order to verify this method, fatigue experiments on two kinds of notched specimens with different notch radius were carried out under constant and block load spectrum. It was found that the modified local stress–strain method was more accurate than the traditional ones, the maximum relative error between predicted and experimental fatigue life was less than 6%.

中文翻译：

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局部应力应变法评估拉压非对称材料的疲劳寿命

本文研究了在应变控制的单轴疲劳载荷下冷拔钢的低周疲劳特性。在整个疲劳寿命中都观察到了循环软化，除了在最初相对较短的时间内显示出循环硬化。在完全反向的应变载荷下发现正平均应力，表明存在明显的循环不对称性。提出了一种改进的局部应力应变方法来估计缺口拉压非对称材料的疲劳寿命。为了验证该方法，在恒定载荷谱和块载荷谱下对两种不同缺口半径的缺口试样进行了疲劳试验。发现改良的局部应力应变方法比传统方法更准确，