Study On Ultrasonic Detection Of Brazing Quality For Aluminum Alloy Honeycomb Panel

Aluminum alloy honeycomb panel has a wide range of application prospects in urban rail vehicle manufacturing industry because of its lightweight characteristics.At present,the connection method of the aluminum alloy honeycomb panel mainly includes brazing and bonding.Among them,the brazed aluminum alloy honeycomb panel has higher joint strength than the bonded aluminum alloy honeycomb panel,and is more suitable for the manufacture of urban rail vehicle.The quality of aluminum alloy honeycomb brazed joints will directly affect the manufacturing quality of urban rail vehicle.Therefore,it is particularly important to test the quality of aluminum alloy honeycomb brazed joints.It is a traditional inspection method to detect the quality of aluminum alloy honeycomb panel joints by destructive means after welding,but the detection efficiency is low and material waste is serious.Ultrasonic testing technology for aluminum alloy honeycomb brazing quality can not only solve the above problems well,but also has the advantages of simple operation,high efficiency,high precision and high degree of automation.It plays an important role in the field of practical engineering.This paper independently developed the ultrasonic testing system for aluminum alloy honeycomb panel brazing quality.This system not only realizes the automatic scanning inspection of the aluminum alloy honeycomb brazing joint,but also can automatically process and analyze the inspection data to form aluminum alloy honeycomb brazing.The ultrasonic C-scan image of joints are used to realize the ultrasonic quantitative detection and evaluation of the brazing quality of the aluminum alloy honeycomb panel.In this paper,the ultrasonic testing process of aluminum alloy honeycomb brazed joints were simulated by COMSOL Multiphysics software.The result shows that the primary echo signal changes more and more with the position of the probe on the aluminum alloy honeycomb panel.It provides a theoretical basis for selecting the amplitude of the echo as the eigenvalue for the ultrasonic testing of the actual aluminum alloy honeycomb panel.In this paper,the time domain analysis and frequency domain analysis of ultrasonic A-scan signal were carried out on the brazed joints of aluminum alloy honeycomb panel,and the time-domain and frequency-domain analysis results of ultrasonic A-scan signal were compared to obtain time-domain measurements.The mean value of the difference from the actual value is 0.13,and the standard deviation is 0.32.The mean value of the difference between the measured value of the frequency domain analysis and the actual value is 0.20,and the standard deviation is 0.69.It can be seen that the time domain analysis measurement can more accurately measure the welding length on the scan line.In this paper,different eigenvalues in the A-scan signal are extracted to generate ultrasonic C-scan image of the aluminum alloy honeycomb brazed joints.By comparison,it is found that the ultrasonic C-scan image generated by extracting the maximum amplitude of one echo amplitude can more accurately reflect the aluminum alloy honeycomb brazed joints.The ultrasonic C-scan image of the aluminum alloy honeycomb brazed joints were subjected to mean filtering and median filtering respectively.After comparison,the7?7median filtering of the template works best.The Canny edge detection is used to extract the boundary of the aluminum alloy honeycomb panel brazed joints,and the window grayscale transformation is used to enhance the image boundaries information,which not only obtains good image quality,but also the joint boundaries are more obvious.The welding length of the scanning line is automatically extracted by the algorithm.Finally,the systematic and quantitative evaluation of the quality of the brazed joints of aluminum alloy honeycomb panel were realized.