断裂性能试验及裂纹扩展寿命分析

Crack Growth Life Predictions Based on Fracture Property Test

通过断裂性能试验确定了某型直升机部件金属材料的断裂韧性和裂纹扩展门槛值，采用多元线性回归方法拟合得到裂纹扩展速率方程的材料常数。采用不同的裂纹分析方法进行了损伤容限分析。研究结果表明：对此型直升机部件的金属材料来讲，应力强度因子变程门槛值对应的应力比上截止限取0．7是合理的；低于安全疲劳极限的小载荷对裂纹扩展寿命有较大影响，尤其是按安全疲劳极限截除小载荷对裂纹扩展寿命的影响是非常显著的，当截除标准低于0．8倍的安全疲劳极限时，裂纹扩展寿命的差别不是很显著。

The accuracy of three damage tolerance analysis methods in determining the crack growth times for the helicopter fracture spectra from the helicopter main rotor were investigated. The results showed that the load less than the safe fatigue limit had an important effect on crack growth time, the load less than 80% of the safety fatigue limit could not be taken into the spectrum because the crack growth life was almost unchangeable when the truncation criterion less than 80%, and it was reasonable for the material that the cut-off stress ratio for the threshold stress intensity factor range was set 0.7