Research On Visual Detection Technology Of Laser Ultrasonics And Its Application In Defect Detection Of Pipe Wall

At present,nondestructive testing methods of pipeline defects mainly include magnetic particle testing,penetrant testing and ultrasonic testing.However,these methods have their disadvantages in the current environment,such as magnetic particle testing method is only suitable for ferromagnetic materials,sensitive to the direction of defects;The penetrant testing method can only detect the defects on the surface,so it is difficult to detect the porous materials,the result is affected by the surface roughness of the material;The results of the ultrasonic testing method is not intuitive,and the coupling agent is needed to detect the material,the method has some restrictions on the shape and complexity of the material.Laser ultrasonic testing is a new branch of ultrasonic testing,which is an interdisciplinary subject involving optics,acoustics,electrics and so on.Compared with the traditional ultrasonic testing technology,laser ultrasonic has many advantages,such as non-contact detection,no couplant,eliminates the influence of couplant,can be used for nondestructive detection of all kinds of complex shape samples,the combination of laser ultrasonic detection and visualization technology plays an important role in the nondestructive testing.The laser ultrasonic visualization technology converts the computer data and calculation result to image by use of graphics and image processing technology,the image is ikonic and specific on the screen,it can express the content contained in the abstract data.In this paper,a new nondestructive testing technology-laser ultrasonic visual detection technology is designed.The technology is combined with laser ultrasonic detection technology and visualization technology,the technology is combined with laser ultrasonic detection technology and visualization technology,using pulsed laser for stimulating ultrasonic signal,through the visual processing of the received signal to realize the ultrasonic visualization of propagation process,then realize the internal pipeline material integrality visual examination.On the basis of the above,a set of holonomic experimental platform for visual detection of laser ultrasound is designed and implemented,The whole experimental platform includes pulse laser,three coordinates mobile platform,control system for platform,test specimen,data acquisition system,optical sensors,and the software system of signal acquisition and visual processing based on Visual Basic language and TeeChart visual component.Through the experimental platform to detect aluminum pipe and cast iron pipe about defective or not by using laser scanning and visual inspection technology to acquire the image of the ultrasonic signal on the inner wall of pipeline and realize laser visual inspection defect.The research and implementation of visual detection technology based on laser ultrasound makes the test results visible,and it will become an important means and development direction of nondestructive testing,its application prospect is very broad.