Study On The Application Of A New Sensitive Organ On The Pulsed Eddy Current Testing

This paper has a research on the pulsed eddy current nondestructive testing system based on InSb magnetoresistor, including hardware and software design. The pulsed eddy current testing is a new development area of eddy current testing technology. The pulsed signal has wide frequency bandwidth and slower attenuation than single frequency sine eddy current. And there is some important information about crack in transient induced voltage.Firstly it is designed a pulsed eddy current testing system with InSb magnetoresistor, including hardware and software. The hardware includes probe design, testing standard sample design, regulating circuit design and so on. The optimal design of the probe is studied. Crack calibration is solved. Environmental temperature interference is restrained efficiently. The software is comprised of three parts. The first part is simulating the magnetic field while the probe is working using the ANSYS finite element analysis software, providing the base for the probe design. The second part is analyzing and processing the acquisition data by Matlab software. The signal is smoothing and filtering through the method of numeral synchronous accumulation, polynomial fitting, wavelet transform. It makes a preparation for picking the signal feature value. It can get the depth of the crack by using the difference between the peak value of the acquisition data on cracks and in air in the end. The third part is constructing a real-time pulsed eddy current system with InSb magnetoresistor through combination of LabWindows/CVI and Matlab to achieve the real-time online testing. Finally the paper gives a lot of experimental analysis results by using the built system. It is showed by the testing results that crack-sensitivity is better and crack-depth testing is satisfactory by using InSb magnetoresistor as the pulsed eddy current testing sensor.