Research On Key Technical Problems In 3-Dimensional Ultrasonic Phased Array Ispection

In the modern industrial production process,due to process design,manual operation and other factors,cracks,pores,slag inclusions and other defects are often present inside the work piece.Because of destroying the internal structure,performance of various aspects of the work piece are reduced greatly.Ultrasonic phased array imaging detection technology is an important non-destructive testing technology in defects detection.Traditional ultrasonic phased array can achieve three common scanning methods: linear scanning,fan-shaped scanning and dynamic focusing scanning by changing the delay time of array elements,which display the defect scanning results by 1-demensional echo signals and 2-demensional slice image.According to the scan image,the defect is evaluated by the professionals.In the 2-demensional imaging process,due to the different scanning angles and focus depths,the propagation directions of the ultrasonic beams and the divergences of beams,the scanning results of defects are different,even result in artifacts and speckles in the image.In the traditional 2-dimensional imaging of ultrasonic phased array,the defects are presented in a slice,which is not intuitive to reflect the volume,shape and position of the defect.Based on the above problems,in order to completely and accurately represent the defect morphology and position,this paper considers the actual industrial application situation,combines 3-dimensional visualization technology with ultrasonic phased array imaging technology,unfolds key technologies required for 3-D imaging ultrasonic phased array.According to the deflection and focusing characteristics of the sound beam emitted by the ultrasonic phased array,the echo signal is analyzed and processed,and a bilinear interpolation algorithm is used to obtain a two-dimensional slice image.By comparing the experimental analysis,which is concluded that different scanning angles and depths of focus have an effect on image speckle and artifacts.Based on this,an algorithm combining multi-angle and dynamic focus is proposed to improve the resolution of 3D volume data.According to ultrasonic phased array detection characteristics,by comparing surface rendering and volume rendering techniques,a mobile cube algorithm is used to reconstruct 3D volume data.Besides,for the characteristics of volume data,Mean Shift clustering algorithm was used to classify the signals and obtain the defect detection results.Through the analysis of the original image and the 3-dimensional defect image,the features of the map of the defect imaging are summarized,and the original A scan signal,the measured work piece are compared.The experimental results show that the obtained 3-dimensional image is intuitive and accurate in reflecting the defect.The research methods and results in this paper can provide reference for the development and popularization of ultrasonic phased array 3-dimensional imaging detection technology.