安-24飞机延寿疲劳试验中裂纹临界长度和扩展寿命的计算

Evaluation of Crack Growth Life and Critical Length of The AN-24 Aircraft under Life-Extending Fatinue Test

在飞机结构疲劳试验中,正确地给出裂纹的临界长度和扩展寿命是圆满完成疲劳试验,并保证损伤后的飞机能够通过剩余强度试验的关键环节。本文采用能量释放率法计算了安-24飞机延寿疲劳试验中主要裂纹的应力强度因子.并确定了临界长度和扩展寿命。这为适时结束安-24飞机疲劳试验,进行l审j余强度试验提供了理论分析依据,这里所给出的确定裂纹临界长度和扩展寿命的分析方法,对飞机结构疲劳试验和剩余强度试验有较高的参考价值;同时,这种分析方法对服役飞机出现裂纹后正确确定检测周期也具有一定参考价值。

In the fatigue test of an aircraft structure,the correct evaluation of crack critical length and growth life is the key to that the fatigue test is successfully completed and the damaged aircraft can be subjected to residual strength test.In this paper the stress intensity factors of generated chief cracks in the AN-24 aircraft subjected to life-extending fatigue test are evaluated by using the energy release rate,and the critical length and growth life of every chief crack are determined,thus providing a basis for theoretical analysis of how opportunely to terminate the AN-24 aircraft fatigue test and how to initiate the residual strength test.The analytical approach developed in this paper and used for evaluation of the crack critical length and growth life is of great,referential value to the aircraft structure fatigue test and residual intensity test.In addition,this analytical approach is of certain referential value to the determination of monitoring proofing cycle of the in-service aircraft structure with cracks.