导波检测金属构件疲劳裂纹的试验研究

Research on Experiment of Detection of Fatigue Crack for Metallic Components by Using Guided Waves

对于金属工程结构而言,疲劳裂纹是威胁结构完整性的关键问题之一,但是金属构件从疲劳裂纹萌生到发生断裂只发生很小的永久变形,很难事先察觉,是一种极其危险的破坏形式,因此对疲劳裂纹进行准确的定性和定量检测具有重要意义。介绍了用导波检测金属试样疲劳裂纹的试验研究,建立了四点弯曲试验装置,对试样施加疲劳载荷,PZT传感器表面安装在试样上,在疲劳试验中被用来激发和接收导波,利用连续小波变换从导波应力波信号中提取特征,表征疲劳裂纹的存在和扩展,同时采用数码相机对裂纹进行图形捕捉,通过试验结果对比表明所提出方法的适用性和有效性。试验结果表明,提出的检测方法能够准确、实时地检测出疲劳裂纹的存在。

For metal engineering structures,the fatigue crack was one of the key problems which threatened structural integrity.However,metal components only had small permanent deformation from fatigue crack initiation to fracture,which was difficult to detect in advance and was an extremely danger form of failure.Therefore,accurate qualitative and quantitative detection of fatigue crack was of great significance.It was introduced that the experimental research on detecting fatigue crack of metal sample by guided wave,and we established a four point bending test device,at the same time,applied fatigue load to the sample with PZT sensor surface installed on the sample.It was used to excite and receive guided wave in the fatigue test,and we extracted characteristics from guided wave stress wave signal by continuous wavelet transform including characterizing the existence and propagation of fatigue crack.At the same time,digital camera was used to do schematic capture for the crack.The experimental results comparison showed the applicability and effectiveness of the proposed method and the experimental results showed that the proposed detection method could detect the existence of fatigue cracks accurately and in real time.