Research On Multi-layerd Metal Thickness Testing System Based On GMR

The thickness measurement of multi-layered metal plate is an urgent problem to be solved in many fields, such as airplane aerofoil thickness, airplane assembly multi-layered thickness. So the thickness measurement of multi-layered plate is being paid more and more attention to.This paper is studied based on National Natural Science Foundation of China (No. 50505045).The detailed contents and chapter arrangements of this paper are as follows:Chapter one: The research significance and research value of multi-layered thickness testing is expatiated. Current research situation of ECT technology are summarized. The development history and the current research situation of ECT technology are summarized. The development and the current situation of the GMR technology are being told off; the development and trait of VI and its flat are introduced briefly. At last the main content and frame of this paper are presented combining with National Natural Science Foundation.Chapter two: The principle of the GMR is introduced, then the principle, the traits, the application of the GMR Sensor are being presented. The principle of the ECT thickness testing is introduced briefly.Aiming at the shortage on the ECT thickness testing technology, the multi-layered thickness testing system based on GMR is put forward. Finally the design on the structure of the expression thickness testing system is discussed.Chapter three: To start with the electromagnetism theory, using the Maxwell equation. By introducing the magnetism vector, a four-layered thickness testing model based on GMR is constructed. At last the magnetic expression of the expression which is above the hollow loop is solved .Chapter four: Based on the model constructed,the design of the hardware system and software system will be accomplished.The hardware circuit includes blazing the powering signal, choosing the Sensor and magnifying and filtering signal.At the same time the multi-layered thickness testing system based on GMR is empoldered.The overall design scheme , the development environment, system function and module are accomplished.Chapter five: In order to validate the correctness of the model, as well as the reliability of the testing system.Some experiments are done through the testing system.By studying the experiment scheme, the influence of the distance , frequency, thickness on the output voltage are studied. Finally the outcome of the experiments are analysed.Chapter six: All of the work in this dissertation are summed up, and the future researches are prospected.