Study On Micro Damage Detection Of Metal Materials By Electromagnetic Ultrasonic-Eddy Current Method

Based on the eddy current testing and electromagnetic ultrasonic transducer several complementary advantages of both,to combine two kinds of detection technology.The combination of two kinds of detection,used to detect defects in different parts,to achieve complementary advantages,improve the reliability of the detection.In this paper,the electromagnetic ultrasonic-eddy current testing technology is taken as the object for theoretical simulation analysis and experimental research.(1)The basic theory of electromagnetic ultrasonic wave detection and eddy current testing based on impedance analysis is studied.The technical parameters,application characteristics and detection range of electromagnetic ultrasonic and eddy current are analyzed.On the basis of theoretical research,the probe structure can meet the electromagnetic ultrasonic and eddy current testing simultaneously were developed and the function and influencing factors of the integrated probe are analyzed.(2)Using finite element simulation software to establish the model of composite detection,and the feasibility of the electromagnetic ultrasonic and eddy current testing are analyzed.In order to improve the signal strength and reduce the electromagnetic wave,the design method of orthogonal test is used to optimize the coil structure and probe parameters respectively.The optimal parameter combination of the probe performance was obtained,and the amplitude of the receiving signal and the surface induction vortex intensity of the specimen were greatly improved.(3)The electromagnetic ultrasonic wave and eddy current defect detection characteristics based on impedance analysis are studied.Including the influence of the horizontal position,height and depth of the internal defects of specimens on the longitudinal wave signal,and the influence of surface crack height and volume on the resistance and reactance of the test coil.It provides the positioning and quantitative analysis basis for the application of electromagnetic ultrasonic and eddy current testing technology in the inspection of the surface defects and the internal defects of the electromagnetic ultrasonic eddy current.(4)Different types of defects in thick metal plate were tested.The experimental results show that the probe structure designed in this paper can not only quickly detect surface cracks,but also can stimulate longitudinal waves with obvious directivity,which can accurately locate and identify the internal defects.