The Signal Analysis Methods of Ultrasonic Guided Wave Propagation Modes in Thin Plate
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摘要: 根据兰姆波在薄板中传播的频散特性，针对超声检测中获取的检测信号，采用双重时间尺度对比的方式，对兰姆波模态进行分析。采用半解析有限元法绘制各向同性自由铝板中兰姆波频散曲线，选用合适的超声换能器获得兰姆波在铝板不同位置的多模态传播信号。在兰姆波整体传播时间尺度下，用二维傅里叶变换对全部数据进行分析，确定了其模态及能量分布，再经过滤波降噪，利用Hilbert-Huang变换分离并精确分辨单个信号内叠加的不同模态的时间尺度。结果表明，上述方法可以识别兰姆波导波模态并获得较高的时间分辨率。
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关键词:
- 兰姆波 /
- 信号处理 /
- 半解析有限元 /
- 二维傅里叶变换 /
- Hilbert-Huang变换
Abstract: In this paper, the modal analysis of Lamb wave was made according to the dispersion properties of its propagation in the thin plateby comparing the two time scales of the signal collected in ultrasonic testing. Based on the dispersion curves of Lamb wave drawn by semi analytical finite element method in the isotropic free aluminum,suitable ultrasonic transducers were selected to obtain modal signal propagation of Lamb wave in aluminum plate in different positions. In the overall time scale of Lamb wave, all the data were analyzed by two-dimensional Fourier transform and the modal and energy distribution would be identified. In the other time scale, the Hilbert-Huang transform was used to separate and distinguish the different modes accurately that were superimposed in a single signal after a reasonable filtering and noise reduction. The results show that we can analyze and compare the signal data of Lamb wave acquired from detection and identify the guided wave mode and get higher time resolution with the above method. -
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