Study On Evaluation Method Of Imaging Quality Of Ultrasound C-scan System

As a non-intrusive testing tool,the ultrasonic C-scan system has the characteristics of easy operation,on-line measurement and high accuracy.It is widely used in non-destructive testing of products or raw materials in industrial fields such as scientific research,boilers,ships,railways and so on.Using ultrasonic C-scan imaging can ensure the quality of industrial products or materials by detecting detections.Although ultrasonic C-scan equipment is widely used and has corresponding standards and specifications to ensure its quality,there is no unified standards or specifications to evaluate the mechanical properties and imaging quality of scanning axis of ultrasonic C-scan equipment.In order to solve this problem,this paper mainly studies the evaluation methods of the quality of ultrasound C-scan images.The main work is as follows:1.A quantitative estimation method of feature parameters of ultrasound C-scan image is presented by combining K-means clustering and improved Graham algorithm.In this method,an ultrasonic C-scan system is used to scan the aluminium alloy specimens with artificial defects of standard shape and obtain the ultrasonic image data.After image filtering,image segmentation,image filling and edge extraction,the edge data of artificial defects in the ultrasonic image are obtained.Then,according to the improved Graham algorithm,the concave and convex data are extracted from the defect edge data.The extracted concave and convex data are fitted to circles to obtain the parameters to be measured.The experimental results show that the method can effectively describe the regional characteristics of standard circular artificial defects and evaluate the imaging quality of ultrasonic C-scan equipment based on the estimated feature parameters.2.In order to solve the problem of blurred edges and errors in the estimation of feature parameters in ultrasonic images,the influence of the beam width emitted by the ultrasonic probe on the estimation of image feature parameters is analyzed,and presenting a method to correct the feature parameters of image.In this method,firstly,analysing the factors of affecting the beam width according to the radiation law of the ultrasonic sound field;secondly,determining the optimal parameters of the ultrasonic C-scan equipment by comparing C-scan images that are with the same defect size under different control variables;finally,correcting the measurement value of defect size according to the gray value distribution law of the defect transition region of the ultrasonic image.The experimental results show that the beam width of the ultrasonic probe has a great influence on the quality of ultrasonic imaging,and this method can effectively correct the measurement value of defect size.3.A software for estimating feature parameters based on ultrasonic C-scan image is designed and implemented.The software can realize the functions of algorithm validation,defect edge extraction,calculation and display of feature parameters,and display of image processing results.