Reverse time migration damage morphology reconstruction algorithm based on laser ultrasonic circular sensing array

Abstract

In response to the quantitative detection needs of damage in large metal thin-walled structures, this paper uses laser ultrasonic detection technology to excite and collect ultrasonic waves, and improves the traditional reverse time migration imaging algorithm to achieve the goal of reconstructing damage morphology. By analyzing the acoustic scattering characteristics, the theoretical basis was provided for damage reconstruction based on circular sensing arrays, and algorithm improvements were made to the traditional time reversal based reverse time migration imaging technology(TR-RTM) in terms of scattered wave extraction and reconstruction accuracy evaluation. We have built a laser ultrasonic detection platform and achieved accurate reconstruction of regular damages such as circles, triangles, and squares based on array wavefield data. However, for irregular damages with dents and sharp corners, we can only reconstruct their approximate contours and analyzed the reasons that limit imaging accuracy. This study laid a theoretical and experimental foundation for the quantitative assessment of damage.