Research On Defect Reconstruction Method Based On Boundary Tangent Fitting Technology

Defect detection has always occupied an important position in industrial production and life.At present,the most widely used defect detection method is ultrasonic non-destructive testing.With the deepening of research on ultrasonic inspection,more and more ultrasonic imaging methods have been proposed and applied,but these imaging methods often have the problem of blurred boundary of defects.Aiming at this problem,this paper proposes a defect reconstruction method based on the boundary tangent fitting technology,taking the internal defects of the gyroscopic workpiece as the research object,using the boundary tangent fitting principle to quantitatively reconstruct the geometric characteristics of the defect and study the impact Factors of defect reconstruction accuracy,explore the applicability of boundary tangent fitting technology to internal defects of workpieces of different sizes.In this paper,ultrasonic cross-section scanning is used to collect echo signals from the cylinder.A simulation scheme of gyroscopic ring scanning method based on CIVA is designed,and the validity of the simulation data is verified,which provides a data set for the subsequent research on boundary tangent reconstruction.The principle of the traditional defect reconstruction method is analyzed and the defects in the center hole and the eccentric hole of the cylinder are reconstructed.Considering the factors of ultrasonic diffusion Angle,the refraction due to the transformation of the medium and the existence of the arc surface when the ultrasonic enters the cylindrical workpiece is analyzed,and the calculation method of the refraction Angle is studied.Substitute to the shape of the common approximation for bubble,crack defects,is studied based on round,oval,defect reconstruction principle and method of polygon model,and the simulation of the circular,oval,triangle and rectangle defect data is verified,the results show that the boundary tangent reconstruction method can accurately reconstruct the defects of specific information.By changing the detection interval,sampling frequency,probe center frequency,probe incident angle,and defect shape and size in the simulation model,the effects of ultrasonic testing methods and defect shape and size on the accuracy of tangent fitting and reconstruction of the boundary were studied;The reconstruction method reconstructs circular defects of different sizes.The results show that selecting the appropriate detection model can improve the accuracy of defect reconstruction.Finally,many different types of defects are reconstructed,and the applicability of the boundary tangent reconstruction method to multi-defect detection is verified.