| In today’s industrial safety,It is found that shafts,pressure vessels,nuclear running equipment,aircraft parts riveting and so on tend to appear fracture,cracks,bubbles.These small defects not only cause huge economic losses,and even lead to catastrophic accidents.There are many ways to detect defects,such as infrared detection,X-ray detection,and ultrasonic testing,and ultrasonic testing is one of the recognized detection methods,but because of its lack of continuous observation of defects,its development is not well.In this paper,a multi-frequency eddy current nondestructive testing system is proposed.It not only can continuously observe the pattern defects,but also own the advantage of high sensitivity,fast speed and sensitive application.The system is used of multi-frequency eddy current technology.The surface and near surface micro defects of aluminum plate are detected by using the space magnetic field sensor HMC1043.Also,it can characterize the defects(length,width,depth).The data acquisition chip is used of STM32F103ZET6,The data communicate with the host computer through the serial port,at the same time we display the collected data on the TFTLCD.Firstly,in this paper,the technical characteristics and development of electromagnetic eddy current are introduced,and the development process of special probe was introduced in detail.We combine with the actual project to carry out analysis of electromagnetic eddy current testing methods and then determine which method should be chosen.Secondly,System hardware,software design and related debugging was introduced.In the aspect of hardware,we design a kind of rectangle coil with high stability and sensitivity,which can greatly improve the detection sensitivity.At last,we used the system to scan the aluminum plate and then the results were analyzed.The influence of the excitation frequency and the geometry defects on the scanned image is discussed by using the control variable method.At the same time,It is proved that the system can detect the surface or the near surface of the aluminum plate and other material defects,and the reference value of practical eddy current nondestructive testing is high. |
