Study On Ultrasonic Phased Array Full Matrix Capture Imaging Technique For CRH Wheel-Set

The currently existing train wheels ultrasonic nondestructive testing system are generally based on the techniques of conventional ultrasound and beamforming-based ultrasonic phased array with focusing and scanning methods. The output of these system is B-scan images which have low detection resolution. Ultrasonic phased array full matrix capture (FMC) method can provide the complete data set and completely reconstruct all of the detection information with total focusing method (TFM). The output image of FMC/TFM method has extremely high resolution but with low detection efficiency.Firstly, here we studied on amount of references and summarized the research progress and status of ultrasonic phased array FMC/TFM method. On the basis of this study, we developed the simulation software for FMC data set based on the theoretical model of ultrasound propagation in physical space and TFM principles. Then we in-depth analyzed the ultrasonic phased array focusing geometric model, and derived the expression for evaluating the minimum A-scan numbers which are required for detecting information reconstruction based on the definition of ultrasonic phased array performance indicator (API). Here we also developed the ultrasonic phased array full matrix capture software based on M2M Multi2000and its remote control server.On the basis of currently existing achievements of references, we firstly constructed the time-consuming model and analyzed the main factors which influencing the FMC/TFM efficiency. Then based on the simulation and acquisition software, we carry out a large number of simulation analysis and experimental verification for detection model. Firstly, we analyzed the factors which influencing the performance of FMC/TFM and the performance improvement for different depth detection with FMC/TFM. Furthermore, we analyzed the influence of random Gaussian white noise on the FMC/TFM detection method based on reasonable assumptions.A large number of experimental analysis and verification showed that the larger the aperture size, the higher the detection performance, and the fewer the number of array elements, the higher the FMC/TFM efficiency. Based on this conclusion, here we propose and validate a high resolution and high efficiency improved method based on increasing the effective aperture, which can greatly improve the FMC/TFM efficiency and maintain the excellent performance. For example, the API of FMC/TFM detection with a64elements array is0.3199, with the technology of increasing the effective aperture, the API of FMC/TFM detection with a3elements array is0.2204, and the TFM computing efficiency is greatly improved three orders of magnitude. Here, we use the improved FMC/TFM method for detecting the CRH wheel which containing artificial defects and the effectiveness has been verified.