转子叶片的外物损伤及疲劳寿命试验研究

为了研究外物损伤(FOD)对叶片疲劳寿命的影响,用能量等效落锤冲击钛合金TC4(Ti-12Al-4A)板试件侧边,模拟转子叶片进气边受到小硬物颗粒冲击时引起的外物损伤,观测冲击后产生的缺口变形特点及缺口尺寸与冲击能量的关系,试验结果表明:冲击产生的缺口深度,随冲击能量的增大而增加,成非线性关系。在不同循环应力下,对外物损伤试件进行了脉动循环应力疲劳试验,试验结果指出,进气边的FOD显著降低叶片的疲劳寿命,损伤试件寿命与无损情况寿命的比值随循环应力的提高而增大;存在与FOD对应的循环应力极限,当工作应力较低时可以不考虑冲击损伤的影响。

Experimental study on foreign object damage and fatigue life of rotor blades

In order to investigate the influence of foreign object damage(FOD) on fatigue life,energy-equivalent impact tests for the sides of TC4(Ti-12Al-4A) plate specimens were used to model the FOD of leading edges of rotor blades.The tests show that the depth of impact notch non-linearly increases with the increase of impact energy on unit thickness.The stress-controlled fatigue tests for the damaged specimens have been carried out.The experimental results indicate that the FOD of leading edges can decrease fatigue life of blades significantly.The ratios of the damaged specimen life to the predicted undamaged specimen life become larger when increasing circulatory stresses.For a given damage there is a limit of circulating stress,and the effect of FOD may not be considered if the active stress is lower than the limit.