Research On Phased Array Imaging Based On Capacitive Microelectromechanical Ultrasonic Transducer

Ultrasound phased array imaging detection technology is a new non-destructive testing technology which has been developed and widely used in recent years.Its basic principle is to apply different delay excitation to the array elements according to a certain sequence to make their emitted sound beams interfere and overlap,so as to control the change of sound beams and get the image display of the internal defect information of the measured workpiece.It is very obvious in the industrial field.Advantages.In this paper,based on the capacitive Micro-Electro-Mechanical ultrasonic transducer(CMUT)phased array scanning imaging technology,the related algorithms for optimization of acoustic field beam,beam deflection focus and array performance are studied.Based on Field II,the simulation analysis is carried out,and the test scheme is designed.The focusing algorithm is verified by phased array system.This paper mainly studies the following aspects:1.Based on the principle of phased array imaging detection technology,a lot of experiments have been done on its transmission and reception process.The display mode of phased array imaging,the deflection,focusing and focusing deflection of synthetic beam are studied.The control variable method is used to simulate the effect of the number of elements,deflection angle,width and spacing of the elements on the sound field of the phased array probe.2.The sound field model of phased array is studied.According to Huygens principle,the sound field model of ultrasonic beam can be overlaid by point radiation sound field characteristics based on spatial impulse response.The function expression from point source transducer to array sound field is given,and the sound field distribution function of any shape and size array transducer is verified.3.A sector focusing algorithm is designed and tested with a phased array flaw detector.Experiments show that the algorithm can achieve sector focusing scanning of-30 ?30,step by step of 2.4.The array sparse optimization algorithm is studied.The array is sparsely designed,and the signal-to-noise ratio of the scanned image is optimized by genetic algorithm(GA).Based on Field II,the continuous defect points are scanned and simulated.The scanning image can obtain the maximum information under the minimum redundancy and has good side lobe characteristics.The optimized array image signal-to-noise ratio is about 4.9db,and the array is sparse,which greatly improves the scanning efficiency of phased array.5.The simulation of one-dimensional linear c MUT imaging process verifies that the fixed-point focusing and fan-shaped focusing scanning algorithms studied in this paper can obtain clear scanning images of defect information.