模态声发射技术在构件疲劳裂纹检测中的应用

疲劳裂纹的萌生和扩展是机械零件在变载荷作用下的主要失效形式,在变载荷下出现疲劳裂纹的同时往往伴随着弹性波的扩散,以迅速释放其内部积累的应变能。使用近几年来得到迅速发展的模态声发射技术真实地获取疲劳裂纹的声发射波形,使接收到的声发射信号较完整地反映了声发射源的物理状态。在波形分析中采用参数分析法提取声发射波形特征,建立模态声发射参数和裂纹扩展速度之间的数学关系。由于综合采用了多种技术的优点进行信号分析、处理,因此根据声发射信号特征得到的结果将更加逼近实际状态。

Detecting Acoustic Emission Signals from Fatigue Crack Propagation

The origination and propagation of fatigue crack in mechanical elements under variable load is the main type of most failures. At the same time, this process is always accompanied by transmitting of elastic stress waves and rapid setting free of thd accumulated energy in the interior of the structure. In the paper, the modal acoustic emission(MAE) thchnique rapidly developed in recent years, is properly introduced to more precisely acquire the actual AE signal waveform, which can be trusted to truly reflect the real physical state of the AE sources in the structure. Then in analysis of the signal waveform of the detected crack, the technique based on AE parameters is used to extract waveform features and thus, to correlate AE parameters with crack propagation velocity. On the basis of both MAE technique and parameter analysis method, it can be said that the obtained result is to be more accurate than traditional AE technique in practical test.