板状结构中多损伤的时间逆转成像评价研究

Identification of Multi-defects in Plate-like Structure Based on Time-reversal

基于Mindlin板理论,采用微扰方法分析得到超声导波与板状结构微损伤相互作用的散射波场,并利用有限元方法模拟研究含损伤的板状结构中激光超声导波场。构建散射波的传递矩阵,采用时间逆转损伤成像评价结构微损伤。将时间逆转损伤成像结果与超声相控阵成像结果进行比较。结果表明,相比于传统的超声相控阵损伤成像,时间逆转成像方法灵敏度高,能对板中的多损伤精确识别,且损伤成像精度更精细。

Based on Mindlin plate theory,the scattered wave fields of the interaction between ultrasonic guided wave and the micro damages in the plate-like structure are analyzed by means of the small perturbation method. The ultrasonic guided wave in the plate-like structure with damages generated by a pulsed laser is researched by the finite element method（ FEM）. The transmission matrix of scattered waves is rebuilt,and the images of mini structural damages obtained by the time reversal imaging method are evaluated. The time-reversal imaging method is more sensitive in terms of the reconstructed damage images than the traditional phased array imaging method,offering both accurate identification of multi-damages in the plate-like structure and higher resolution images of damages.