Research On Key Technologies For Planar Eddy Sensor

The cracks and fatigue damage on equipment component surface will change the surface conductivity and planar eddy sensor can measure the surface conductivity precisely. Thus according to the measured conductivity the surface condition can be viewed. of the key part of equipments, such as and permeability. So it is important to study the key technologies for planar sensor.At present, no work has been done about planar eddy sensor inland. On the basis of discussing the state of the art of research on planar eddy sensor technique overseas, several key techniques for planar sensor are studied in this thesis. The brief structure of the research are as follows:Technologies for model of sensor are researched. Begin with Maxwell's equations and analytical model of the sensor is developped based on the collocation points method and the Fourier series theory. Because of the sensor's periodic structure, the sensor response can be precisely predicted via analytic model. Meanwhile, the model based on Finite Element Method (FEM) is developped, and the sensor response can be obtained via FEM model. Based on FEM model, the sensor's sensitive orientation is researched and the sensor design is improved.Technologies for the producing and utilizing of mesurement mesh are researched. Caculating the sensor responses under varies of physical property and lift-off and saving them as a database in the form of 2-D mesh. The mesh describes the nonlenear mapping relationships between the property of the material under test, liftoff and the sensor responses. Additionally, the search and interpolation algorithm for the mesh are researched, then the physical property and liftoff can be derived from the response quickly.Technologies for sensor response calibration are researched. In order to inquire the measured response in the database, the responses need to be calibrated. Three types calibration method is researched, including air point calibration, air-short calibration and least square error calibration.Finally, two parts experiments are established including measurement of the aluminum pad conductivity and the image of surface fatigue. The research results have been shown to be of validity.