The Applied Reasearch On Detecting Flaws In The Steel Tube Based On Ultrasonic Field Of Array

Detecting flaws and thickiness testing in the steel tube based on ultrasonic field of array was researched in the thesis.Conventional ultrasonic automated thickness testing and detection imaging system is widely used in thickness testing and detection of lateral and vertical defect. However, if the size of probe is larger than the size of the defect layered, we usually find the received signal is uncertain,and the system can not detect the small size of defects in layered.The experiment of the array probe is carried on to improve the accuracy in the thickness testing and detection of defect.The detection and localization of defect of the reliability and accuracy can be affected by the ultrasonic field distribution.The design of array probe and parameters of the consistency have a great influence on its issued ultrasonic field. We can made a solid foundation for the ultrasound scaning imaging by designing and testing the parameters of performance of every probe.In ultrasonic testing, ultrasonic phased array technology and synthetic aperture focusing technique have been proved to be two kinds of effective new technologies. In the experiment, each probe is gived the phase delay to achieve focus in a specific location.we can improve the SNR and the defect of resolution of detection system in this way. Synthetic aperture focusing technique can be achieved high lateral resolution at a lower frequency. Its content is very rich in imaging technology. By comparison of B-type imaging,SAFT scaning image and the improved SAFT scaning image,it can be found that the effect of the improved SAFT algorithm is the best.Though the SNR is lowed in the experiment,the imaging resolution is enhanced effectively.A new way called eight array stimulated at the same time was mentioned to produce a plane wave ensure acoustic energy in the layered in summarizes, we can calculate the defect in the layered using signal synthesis of a single array element signal or a finite number of array elements to ensure that the resolution of detection in defect in the layered has been improved.