Research On Phased Array Ultrasound TFM Imaging Method Based On Defect Scattering Characteristic

Ultrasonic phased array can synthesize different beams for defect imaging detection by setting different delay rule, and it has the characteristics of large scanning range and high detection accuracy, which is one of the most promising applications of ultrasonic nondestructive testing technology. With the development of hardware technology, phased array ultrasonic testing system has been developed rapidly, but the development of signal processing technology is relatively slow, which makes the phased array detection signal has not been effectively used. The main reason is the lack of effective synthesis of the sound beam propagation model, lack of understanding of the interaction between ultrasonic and defects.Aiming at these problems, this paper established a finite element propagation model of phased array ultrasonic testing, using the finite element model to research the scattering field distribution characteristics of different phased array ultrasonic beam interaction with typical defect, and analyzed the defect scattering characteristics on the influence of phased array ultrasonic imaging testing.On the basis of the phased array ultrasonic interaction with typical defect, the full matrix capture(FMC) process is simulated by finite element method, and the full matrix data of the defect of phased array ultrasonic testing is obtained. According to the principle of the total focusing imaging method(TFM), the phased array ultrasound TFM imaging software is designed, TFM imaging was performed on two typical defects. Moreover, the TFM imaging results of different defects and the effect of defect scattering on TFM imaging is compared and studied.Based on TFM imaging, extracted defect scattering coefficient matrix from full matrix data, compared to the chart of partial scattering coefficient matrix of different defect, proposed a defect recognition method based on the partial scattering information, and analyzed the relation between partial scatting coefficient matrix and full scattering coefficient matrix. Finally, the TFM imaging results of different defects is verified by experiments.