A Fitting Method For Reconstruction Of Internal Defects Of Cylindrical Components Based On Tangent Relation

The cylinder component,which is typical of pipe,bar and shaft,is widely used in many fields,and defect detection is an important step to ensure the safety of production.In this paper,based on the ultrasonic technology,the reconstruction algorithm of the internal defects is studied.According to the basic components and the internal cylinder defect types,the ultrasonic detection method,principle and propagation characteristics are introduced,and pzflex software is used to simulate the pressure diagram of the propagation of ultrasonic wave in boundary and defects.Based on the analysis of the shortcomings of the traditional method of reconstructing the transit time and the reasons for its occurrence,the paper proposes a method of reconstructing the defect boundary based on the tangent relation;According to the geometric relations of circle,ellipse,rectangle and circle,the boundary reconstruction method of circular hole,elliptical hole and crack is studied,and aiming at the problem that the tangent of ellipse and circle is not easy to solve the closed solution,a new method is proposed to solve the problem that the ellipse hole is tangent to the wave front.Then through the actual defect data acquisition and pzflex simulation of the defect echo signal reconstruction algorithm was validated and the accuracy assessment results show that the relative error of reconstruction results are not more than 5% and the reconstruction result is good.In order to extract the characteristic of the echo time for defect reconstruction,the defect echo is calculated by deconvolution.