Research On Ultrasonic Nondestructive Testing Technology Of Extruded Bars Based On Recursive Analysis Of Backscattered Signal

The research is based on the funding of Basic Scientific Research Project of Central University,Natural Science Fund Project in Zhejiang Province and Chaozhou ScienceTechnology Plan Project,combining the equipment research and development project commissioned by enterprise.In this article,extruded bars are regarded as the research object.Based on the ultrasonic backscatter signal processing technology and recursive analysis technology,the article researches on ultrasonic non-destructive testing technology of extruded bar defects,and establishes an ultrasonic non-destructive testing system.This article first inductive analysis the types of defects and the difficulties of ultrasonic non-destructive testing of extruded bars.Then the article researches on the theory of ultrasonic testing technology for extruded bars,especially the theories of ultrasonic detection methods of extruded bars with different cross-sectional shapes and ultrasonic focusing probes.The backscattered signal composition of extruded bars based on pulse reflection method was modeled and analyzed.Based on the CIVA,a round and rectangular cross-section bar model was established.The simulation of ultrasonic sound field in the bar model under different ultrasonic probe parameters is calculated.Based on the simulation results,the principles of selecting ultrasonic probes for ultrasonic non-destructive testing of extruded bars are summarized,and a multi-focus probe detection mode using zoned focus and combined detection is proposed to complete the ultrasonic non-destructive testing of extruded bars.The ultrasonic detection technology of extruded rods is studied,and a path planning scheme for the ultrasonic detection process of extruded bars based on robot is designed.And the specific scheme was simulated and optimized.The simulation results show that the robot ultrasonic testing technology is especially suitable for the non-destructive testing of large-scale small-sized,multi-specification and complex-shaped extruded bars.The ultrasonic detection signals of extruded bars were processed in time,frequency and time-frequency domains,and the limitations of these methods in detecting typical defects of extruded bars were pointed out.Based on previous research work,the recursive analysis technology was used to identify the ultrasonic backscatter signals of artificial simulated defect test blocks,which verified the feasibility of recursive analysis for ultrasonic detection signal processing.Using recursive plot and recursive quantitative analysis,the natural defect detection signals of extruded bars are mainly studied,and the influence of defects on the recursive characteristics of signals is analyzed.An ultrasonic nondestructive testing system for extruded bars based on recursive analysis of backscattered signals is designed and constructed.Using this system,ultrasonic testing experiments were performed on copper alloy rectangular cross-section extruded bars.Destructive comparison experiments show that the backscatter signal recursive analysis technology can correctly identify the defect signals of extruded bars.In summary,this article mainly researches the ultrasonic non-destructive testing method of extruded bars based on the backscatter signal recursive analysis technology.