Study On Flexible Ultrasonic Phased Array And The Application In Non Destructive Testing

Flexible phased array ultrasonic testing technology is on the basis of flexible materials,then use multiple linear arrays transducer and rely on controlling each phase to achieve deflection and focus of sound field of the beam in irregular shape work-piece, so as to achieve the technology of the irregular shape work-piece internal defect detection. At present, the flexible phased array inspection system still exist many defects such as the big phase deviation and the low imaging resolution.Thus it become one of the hot research topic in recent years.Phase correction accuracy of phased array system is one of the important ways to improve the beam control ability and reduce the signal distortion, which directly affect the detection performance of the flexible ultrasonic phased array to defects.Scholars has made the detailed analysis and research in the flexible phase distortion problem of ultrasonic phased array system when they introduced the NDT especially the research background and current development situation of it.To reduce the phase offset estimation error and improve the precision of phase compensation,and put forward optimization scheme to flexible phased array inspection system, this article will study from the following aspects :(1) Starting from the theory of acoustic field of phased array system,construct transducer acoustic field model, analyze the phase time delay control theory of beam, and discuss the phase control precision problem.(2) Based on correlation analysis, this paper discuss and improve the related phase estimation method that commonly used,and propose compound related phase correction model based on adaptive threshold adjustment.According to MATLAB simulation results, that the compound related phase correction method associated with significantly is lower than that of single phase deviation estimation,which can obviously improve the precision of phase compensation. What’s more, the composite relative phase correction model based on threshold adjustment can be adaptive correction system in the iterative detection threshold, and increase the deviation estimation precision of calibration model.(3)Starting from the theory of wavelet analysis and in view of the composite phase correction model of noise relatedproblems, put forward that add poor level wavelet transform to compound related phase correction model. I also did the MATLAB simulation experiment. The results of the experiment show that the method can effectively suppress the influence of the noise in the calibration model and avoid the additional phase difference caused by general wavelet transform that further improve the precision of phase correction.(4)On the basis of flexible phased array structure characteristics,this paper studies the flexible arrays transducer positioning methods and effectiveness of the decision and using phase correction compensation mode.It also construct the adaptive flexible phased array ultrasonic testing system.The simulation research and defect detection experiments show that the system can enhance its focus ability, improve the efficiency of detecting defects and improve the flexible phased array imaging effect by iterative detection.