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一前言低循环疲劳与高周疲劳的主要区别在于前者以塑性变形为主,疲劳寿命主要由塑性变形控制,后者以弹性变形为主,疲劳寿命主要由应力控制,故加载速度对材料的变形行为、物理、化学、机械性能以及疲劳寿命的影响,前者远大于后者。所以,在关于低循环疲劳试验方法中,对加载频率必须作出相应的规定。文献中规定,当疲劳寿命N_f<10~3次时,加载频率f可采用(6～30)次/分;当N_f>10~3时,f取(60～120)次/分。另一些文献则建议f取(6～60)次/分。(12～300)次/分。而美国ASTME606-80规范中则限定试样在加载过程中,其温度的升高不超试2℃。由于过高的加载频率会影响疲劳试验结果,过低又会使
A preface The main difference between low cycle fatigue and high cycle fatigue is that the former is dominated by plastic deformation. The fatigue life is controlled mainly by plastic deformation. The latter is dominated by elastic deformation. The fatigue life is mainly controlled by stress. Therefore, Behavior, physics, chemistry, mechanical properties and fatigue life, the former is much larger than the latter. Therefore, in the low-cycle fatigue test method, the loading frequency must be made accordingly. The literature provides that when the fatigue life N_f <10 ~ 3 times, the loading frequency f can be used (6 ~ 30) times / min; when N_f> 10 ~ 3, f takes (60 ~ 120) times / min. Others suggest f take (6 ~ 60) times / min. (12 ~ 300) times / min. The United States ASTME606-80 norms in the limited sample loading process, the temperature rise does not exceed the test 2 ℃. Due to the high loading frequency will affect the fatigue test results, too low will make