基于疲劳热响应的高强钢疲劳剩余寿命预测

为了在不破坏材料的情况下估算服役结构材料的使用寿命，尤其是估算承受过未知周次循环载荷（已受损）的材料剩余疲劳寿命，提出一种预测高强钢试件剩余疲劳寿命的方法。以300M钢为研究对象，在不同的循环应力水平下进行疲劳试验，所有的试验过程使用红外成像仪对试件进行全程温度监控，记录了试件在不同损伤阶段的受激温升斜率以构造包含金属疲劳热响应和疲劳寿命对应关系的“参考斜率曲面系”，并以此为依据估算剩余疲劳寿命。试验结果表明受激温升斜率与疲劳损伤状况，即试件的累计受载周次存在明显的线性关系。经试验验证，发现剩余寿命预测的误差不超过5%，说明该线性关系可作为估算剩余疲劳寿命的指标。

Remaining Fatigue Life Prediction of High-strength Steel Based on Thermal Response of Fatigue

To estimate the useful life of servicing structural material by nondestructive approach, especially to estimate the remaining fatigue life of specimen that have undergone unknown number of cycles of loading, a remaining fatigue life prediction method is proposed in this paper. Using 300M steel specimen to perform fatigue tests with different cyclic load amplitudes, the temperatures of all specimen are monitored by infrared thermography during the whole tests. The data of slopes of initial temperature rise caused by excitation load is recorded to construct the "reference slope surface series" which reflected the relation of the thermal response of specimen and fatigue life, this is the foundation for estimating remaining useful life of high-strength steel. The results show that slope of initial temperature rise caused by excitation load is linearly related to fatigue damage, that is, accumulated numbers of cycles of specimen. The experimental verification suggests that the error of this remaining fatigue life estimation is less than 5%; hence, this relation can be employed as an indicator for estimating remaining fatigue life.