复合材料声发射信号传播特性试验研究

Experimental research for propagation of acoustic emission signals across composites

为了获取直升机动部件疲劳损伤声发射信号的传播特性,搭建了声发射数据采集系统,对直升机动部件常用碳纤维材料试件和蜂窝材料试件进行了传播特性断铅试验,利用谐波小波包分析了声发射信号在各个频带上的衰减特性,克服了传统小波包分析能量泄露、频带选取不灵活、不同层频率分辨率不同的缺点。研究结果表明:对于所研究两种试件,100～200 kHz频带的衰减特性与原始信号基本一致,可以代替原始信号进行定位和损伤识别研究,频率越高,衰减越快,衰减较大的无损检测场合,适合选择较低频率范围提取信号特征,对于所研究碳纤维材料试件,200 mm之后声发射信号衰减特性偏离理想衰减特性很大,限制了传统声发射源定位方法的应用。

To get the propagation property of fatigue damage acoustic emission signals across helicopter moving component,the data acquisition system of acoustic emission was set up,a series of experiments were carried out on carbon fiber composites sample and honeycomb sample,and AE signals were obtained from standard pencil lead break sources.Harmonic wavelet packet was used to analyze the attenuation characteristics of AE signals on different frequency bands,which overcome the shortcomings of traditional wavelet packet including energy leakage,inflexible frequency band selection and different frequency resolution on different levels.The results indicate that for the examination samples,the attenuation characteristics of 100 kHz to 200 kHz are agreement with the original signal,which can be used to fatigue damage location and identification instead of the original signal.The higher the frequency,the quicker the attenuation speed,and for the larger attenuation non-destructive testing occasion,lower frequency range is suitable for extracting signal characteristics.For the carbon fiber composites specimen,after 200mm propagation,the attenuation characteristics deviate from the ideal attenuation characteristics,limiting the application of traditional acoustic emission source location method.