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从预压应力循环对疲劳寿命影响的角度研究了疲劳损伤效应。预压应力循环造成试样缺口附近的显微硬度增加和位错密度增高,同时导致损伤和增强两方面效应。经历过载系数0.85～1的预压应力循环5×10~4～10~5次以后,缺口试样的弯曲疲劳寿命提高50～60％。当预压应力循环5×10~5次以后,损伤效应占主导地位,疲劳寿命接近或低于未经预压缩循环的试样。当预压应力循环的过载系数为1.2～2.0时,其增强效应降低。
The fatigue damage effect is studied from the perspective of the effect of preload stress cycling on fatigue life. Pre-stressing cycles result in increased microhardness and increased dislocation density near the notch, resulting in both damaging and enhancing effects. The bending fatigue life of notched specimens increased by 50 ~ 60% after undergoing 5 × 10 ~ 4 ~ 10 ~ 5 cycles of prestressing stress cycle with overload coefficient of 0.85 ~ 1. When the pre-stress stress cycle 5 × 10 ~ 5 times, the damage effect dominates, the fatigue life is close to or lower than the sample without pre-compression cycle. When the overload stress coefficient of the preload cycle is 1.2 ~ 2.0, the enhancement effect decreases.