Research On Modeling Of Phased Array Ultrasonic Field And Its Automatic Detection Technology

Phased array ultrasonic nondestructive testing technology can meet the needs of complex structures,near-end and near-surface defects detection applications,and reduce dead and blind areas effectively due to its ability of flexible beam synthesis and adaptive control.Moreover,its dynamic focusing ability greatly improves the performance of imaging detection.Therefore,this technology has become one of the hotspots of research and application in the field of non-destructive testing.However,after decades of development,despite the rapid development of phased array ultrasonic nondestructive testing technology,the technology needs to be further studied at the theoretical,technical and application levels with the continuous expansion of the scope of application and the diversification of industrial testing objects and requirements.In fact,the effective implementation of phased array ultrasonic nondestructive testing technology depends on the optimal design of transducer and the reasonable selection of beam synthesis parameters.And ultrasonic field modeling and its detection technology constitute the theoretical and application basis of the technology research.However,the current ultrasonic field modeling theory is mainly developed for homogeneous media,there are also some problems in the acoustic field detection and reconstruction methods,such as low automation,unfriendly characterization of test results.Based on above backgrounds and funded by the National Natural Science Foundation of China(NO.51675480),this study develops the research on modeling of phased array ultrasound field and its automated detection technology.While analyzing the research status and future trend of phased array ultrasonic nondestructive testing and ultrasonic field modeling and its detection method,elucidating the challenges and problems faced by related technologies,this study focuses on the theory of phased array ultrasound field modeling in laminated structures and the key technologies of ultrasound field characteristic parameters detection,visualization of ultrasound field distribution and so on.At the same time,using distributed architecture and modular design strategy,integrated with mechatronics technology,a set of ultrasound field detection system is developed.And relevant experiments have been carried out to verify the applicability and efficiency of the theories proposed by this study.The main contents of this paper include:Chapter 1 states the technological superiority and the research status of phased array ultrasonic nondestructive testing,clarifies the significance of research on ultrasound field modeling and its detection technology,analyses the problems of ultrasonic field modeling and its detection,then puts forward corresponding countermeasures.Finally,the research contents and chapters of the paper are arranged.Chapter 2 achieves theoretical modeling of phased array ultrasonic field.On the basis of modeling the ultrasonic field of rectangular single element by ray tracing method and defining the ultrasonic effect of interface in laminated structure,the theoretical modeling of phased ultrasonic field in homogeneous medium and laminated structure has been completed.And a simulation study has been carried out.Chapter 3 studies the optimization control of phased array beam and the automatic detection technology of its characteristic parameters.In order to optimize the directivity of phased array beams,the optimal control techniques based on delay superposition method and minimum variance method in feature space are realized respectively.Due to the latter can adjust the delay adaptively,it has higher imaging resolution than the former.At the same time,while measuring the basic data of ultrasonic field by hydrophone,synthesizing the phased array beam,using the strategy of beam feature points automatic searching,the automatic detection of characteristic parameters such as focal length,focal spot diameter and focal column length is realized.Chapter 4 develops a kind of phased array ultrasound field reconstruction and its visualization technology.Based on the interpolation pretreatment of two-dimensional ultrasonic field data,the spatial frequency domain model of phased array ultrasonic field is established by using angular spectrum method,and three-dimensional acoustic field reconstruction is realized.At the same time,Matching Cubes algorithm is used to extract the isosurface of the three-dimensional sound field to realize the visual representation of three-dimensional sound field with isosurface color mapped and transparency processed.Chapter 5 realizes the automatic detection system for phased array ultrasonic field while using distributed architecture and modular design strategy,completing the design and development of hardware and software modules,and using PXI bus as communication bridge.Besides,relevant experiments are carried out to verify the feasibility and validity of technology and system developed in this paper.Chapter 6 concludes the new developments resulted from this paper and discusses more possibility that can be explored in the future.