Ultrasonic Phased Array Technique And Acoustic Field Study Of Cylindrical Scatterer In Isotropic Solid

As a new nondestructive testing technology,ultrasonic phased array technology has developed rapidly in recent years.The deflection and focusing of wave beam can be realized flexibly.It can get rid of the limitation of component shape and has the advantages of convenient operation,wide scan range and real-time imaging.Thus it can be widely used in medical,industrial,component testing,aerospace,marine,rail and pipeline detection.But for internal defects of complex components,serious acoustic scattering will be a challenge for imaging detection.The phased array technique is applied in this paper to the study of scattered field caused by cylinder in solid and carried out some work.First ultrasonic phased array technique is compared with synthetic aperture technique,and the transient acoustic field with phased array transmitting signal blocked by defect is obtained by set up an emulational model for air bubble embedded in steel structure.Signal is transmitted and received by the same probe of line array in turn which yield to the principle of synthetic aperture and the total acoustic field dealt with a delay processing and array stack is obtained.And then a series of acoustic field signals which focused on both sides of defect are collected by changing focus position.These signals are ruled by beam path location to map a three-dimensional sound pressure figure and an imaging for the realization of air bubble location.This paper puts forward a method that phased array technique is applied to the scattered field study caused by cylindrical objects.The classical elastic cylinder scattering theory solution is given under the plane wave incidence and verified by a simulation model.And then the scattered field distributions are obtained under the line array transmitting and the deflection and focusing function of phased array and compared with the theory solution.These results show that the intensity of acoustic field is increased under the phase array transmitting,and the distribution of scattered acoustic pressure can be improved which makes acoustic field more smoother.Finally phase array technique is applied to the scattered field of two cylinder.Finally a preliminary study of scattered field for inhomogeneous medium in solid is carried out with phased array technique.A solid medium model filled with tiny scatterers is constructed by Waterman's homogeneous medium model and the multiple scattering theory.The scattered acoustic distribution under different volume fraction of scatterer is maped by this model.And then the characteristics of scattered waves is analyzed by studying the scattered longitudinal and transverse waves from the forward,backward,lateral direction resulted from different materials.