薄板声——超声检测信号的时频分析研究

Study on time-frequency analysis for acousto-ultrasonic testing signal in thin plates

本文以兰姆波的群速度-频厚积频散曲线为基础,采用基于短时傅立叶变换的时-频分析方法,对薄板中传播的声-超声信号进行了处理分析。对厚度为2 mm薄钢板的声-超声检测实验结果证实,在声-超声检测形式下激发的超声波的主要成分是多模式的兰姆波。与现有文献中介绍的基于时间域识别的薄板声-超声信号分析方法相比,时-频分析方法不仅可以很好地识别兰姆波模式,而且可对各模式波的能量成分进行分析。

Based on the curve of group velocity-frequency multiply thickness.The time-frequency analysis method based on short time Fourier transform is used for analysis of acousto-ultrasonic signal which propagates in thin plate.The result of acousto-ultrasonic testing experiment of the thin plates of 2mm in thickness makes clear that in the acousto-ultrasonic technique,the excited Lamb waves are multimode Lame waves.Compared with acousto-ultrasonic signal analysis in the thin plate which is based on time field,time-frequency analysis can not only recognize Lamb wave mode but also can analyze energy component of each wave mode.