Ultrasonic Imaging Method Of Weld Seam Based On Synthetic Aperture

Ultrasonic testing technology is one of the most common,most frequently used and fastest growing non-destructive testing methods in the world today.It is mainly based on the acoustic characteristics of the ultrasonic wave.When it encounters an abnormal structure in the interior of the object,it will reflect back to the receiving end and determine the presence and nature of the defect based on the amplitude of the echo signal.The ultrasonic detection system of welds mainly obtains the complete defect detection image by controlling the delay phase of emission and reception of each wafer unit group in the ultrasonic probe,and obtaining different depths of focus and different angles of sound beams.Ultrasonic inspection imaging technology for welding seams has become a hot topic,and it has begun to move from the laboratory to industrial applications.Based on the principle of ultrasonic detection and imaging of welds,this article starts from the aspects of improving the detection resolution and improving the imaging quality.Firstly,the related theoretical knowledge of ultrasonic testing of welds is discussed,including the basic knowledge of ultrasonic waves,the basic principle of ultrasonic detection of welds,and the sound field characteristics of ultrasonic waves.By analyzing the sound source's sound source size,the sound wave length,the relationship between the signal frequency and the sound field,it provides a theoretical basis for the subsequent ultrasonic imaging.Finally,the characteristics of ultrasonic imaging,the causes of imaging deviation and the evaluation factors of imaging quality are analyzed to provide the basis and reference standard for the subsequent image evaluation.Secondly,the basic theoretical knowledge of synthetic aperture focusing technology is discussed and studied.The synthetic aperture method for different transmission and reception methods is introduced.The synthetic aperture imaging algorithm and the time-delay focusing focusing process are also analyzed.Finally,the methods of centrally controlling the acoustic beam are analyzed and discussed.The apodization function is used to control the amplitude apodization of the amplitude,and the dynamic aperture means of controlling the depth of focus,and at the same time paving the way for the basic knowledge of beam simulation.Finally,according to the advantages of the synthetic aperture,the synthetic aperture focusing is combined with the ultrasonic detection of the weld to improve the results of the focusing.First,beamforming was used to compare the directionality of the conventional ultrasonic beam and the directionality of the detected beam after synthesizing the focus processing detection data.The simulation results show that the synthetic aperture technique has a lower sidelobe of the sound directionality image,and the focusing effect is better,and the better imaging quality can be obtained compared to untreated.At the same time,through the weld defect experiment,it is further demonstrated that the synthetic aperture focusing algorithm can be used to improve the ultrasonic imaging of welds and achieve the purpose of detecting defects.This method is feasible.