Fatigue crack growth monitoring using high-frequency guided waves
Fatigue crack growth monitoring using high-frequency guided waves
复制标题
DOI：
10.1177/1475921713498532
复制
发表时间：
2013-09-01
影响因子：
6.6
通讯作者：
Fromme, Paul
中科院分区：
文献类型：
--
作者：
Masserey, Bernard;Fromme, Paul
飞机维修中的一个常见问题是紧固件孔处由于应力集中而产生的疲劳裂纹。高频导波允许对结构的关键区域进行结构健康监测，并可使用非接触式激光干涉仪进行高精度测量。研究了用标准瑞利楔形换能器激励并沿结构传播的一种具有良好灵敏度的高频导波检测微小缺陷的方法。铝合金拉伸试件紧固件孔边的疲劳裂纹扩展是由结构的循环载荷引起的。对裂纹长度进行了光学监测，并与预期扩展速率的断裂力学计算结果进行了良好的相关分析。利用非接触式激光干涉仪对疲劳损伤引起的导波信号的变化进行了监测和量化。测量结果表明，该方法对疲劳损伤的早期检测和对紧固件孔处疲劳裂纹扩展的监测具有良好的灵敏度。利用三维有限差分程序对高频导波的传播和散射进行了数值模拟。随着疲劳裂纹面积的增加，超声信号的实测值和预测值之间有很好的一致性，原则上可以近似确定缺陷的大小。
A common problem in aircraft maintenance is the development of fatigue cracks at fastener holes due to stress concentration. High-frequency guided ultrasonic waves allow for the structural health monitoring of critical areas of a structure and can be measured with high accuracy using a noncontact laser interferometer. The use of a specific type of high-frequency guided ultrasonic wave that has good sensitivity for the detection of small defects, excited using a standard Rayleigh wedge transducer and propagating along the structure, has been investigated. Fatigue crack growth at the side of a fastener hole in a tensile, aluminum specimen was induced by cyclic loading of the structure. The crack length was monitored optically and showed good correlation with fracture mechanics calculations of the expected growth rate. The changes in the guided wave signal due to the fatigue damage were monitored using a noncontact laser interferometer and quantified. The measurements show a good sensitivity for the early detection of fatigue damage and for the monitoring of fatigue crack growth at a fastener hole. The propagation and scattering of the high-frequency guided ultrasonic wave has been simulated numerically using a three-dimensional finite difference code. Good agreement was found between the measured and predicted changes of the ultrasonic signal for the increasing fatigue crack area, allowing in principle for the approximate sizing of the defect.