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研究了一种基于压电传感器阵列和主动Lamb波的结构损伤成像方法,有助于克服Lamb波在板结构中、特别是在复合材料板结构中存在的频散、多种模式及模式转换的现象给结构健康监测带来的困难。分析了结构多损伤散射信号的时间反转聚焦原理,在此基础上提出了一种基于Shannon复数小波和时间反转聚焦的信号合成成像方法。该方法中,确定Lamb波响应信号的到达时刻是信号能够准确聚焦的关键因素之一。提出了利用Shannon复数小波变换计算Lamb波响应信号到达时刻的方法。在碳纤维复合材料板结构上对整套信号合成成像方法进行了验证。研究结果表明,该方法能够有效地对同一个监测区域中的多个损伤进行成像定位。相对于30 cm×30 cm的监测区域,定位误差不超过2 cm。该方法有助于结构健康监测技术的工程应用。
A structural damage imaging method based on piezoelectric sensor array and active Lamb wave is studied, which can help to overcome the dispersion of Lamb wave in the plate structure, especially in the structure of the composite plate, various modes and mode switching Phenomena pose structural health monitoring difficulties. The principle of time-reversal focusing of multi-damage scattering signals is analyzed. Based on the analysis, a signal synthesis imaging method based on Shannon complex wavelet and time-reversal focusing is proposed. In this method, determining the arrival time of the Lamb wave response signal is one of the key factors that can accurately focus the signal. A method to calculate the arrival time of Lamb wave response signal using Shannon complex wavelet transform is proposed. The whole set of signal synthetic imaging method was verified on the carbon fiber composite plate structure. The results show that this method can effectively locate multiple lesions in the same monitoring area. Relative to 30 cm × 30 cm of the monitoring area, the positioning error does not exceed 2 cm. This method contributes to the engineering application of structural health monitoring techniques.