板状结构Lamb波频散补偿与聚焦接收成像检测

对板状结构中Lamb波的频散和多模现象进行了理论分析,采用有限元仿真方法获取了Lamb波与缺陷作用后的回波信号,对信号进行聚焦接收处理,即在一定距离范围内利用导波频散特性对各个模式信号进行频散补偿,提取补偿后信号的幅值,结果表明当所得信号幅值最大时,所对应的补偿距离等于缺陷与换能器之间的实际距离.利用这一结论,提出了以...

Lamb wave dispersion compensation and imaging detection

The dispersion and multi-mode phenomena of Lamb waves in plate structures are analyzed theoretically, and the echo signals of Lamb waves acting on defects are obtained by finite element simulation method. To focus of the received signal, that is, the dispersion compensation of each mode signal is performed within a certain distance range using the dispersion characteristics of the guided wave, and the amplitude of the compensated signal is extracted. The results show that the compensation distance is equal to the actual distance between the defect and the transducer when the signal amplitude is the maximum. Based on this conclusion, a guided wave focusing imaging algorithm based on searching the peak value of the dispersion compensated signal is proposed. The effectiveness of this algorithm is verified in a 3D model plate. Compared with the guided wave imaging algorithm based on delay superposition, it can obtain high-precision defect images with less number of sensors. The proposed algorithm cleverly utilizes the dispersion and mode conversion characteristics of Lamb waves to detect and image defects, which shows the feasibility of the dispersion compensation imaging method for the defect detection of plate structures.