Research And Implementation Of Automatic Detection Of Spinning Cylinder Defects Based On Array Eddy Current

There are many kinds of safety problems in the fields of industrial and military because of the mechanical defects,such as the roll mark,oxidation,pitting,bubble,folding,tensile crack and so forth.These defects are hard to be detected through artificial way especially the small or shallow flaws.In the application fields of military,nuclear and aerospace,the metals structure part is easy to suffer from stress concentration and endure alternate load,which easily leads to fatigue break on the surface which will result in the major safety accident.Therefore,it's of great importance major security.The aim of this thesis is to reach the needs of nondestructively testing the surface defects of spinning shells of military weapons.By analyzing the characteristics of the test object,an automatic test system would be proposed,which can automatically and nondestructively test the surface of the metal spinning cylinder.This system mainly used to grasp and scan the surface automatically,and then identify and locate the defects.In accordance with the requirements,the main research contents are listed below:1.In chapter 2,a feasible technique is used to design the test system after analyzing the characteristics of the detecting target.In order to deal with the problems that may occur in the detecting process,many nondestructive algorithms and methods are discussed.2.In chapter 3,a nondestructive testing instrument is designed depending on the target characteristics,and the parameters of the instrument are optimized in order to improve the detecting performance.Furthermore,the software based on the Model view controller(MVC)three-tier logic architecture is designed,which could match up the detecting process of the instrument.3.In chapter 4,defects detecting algorithms are proposed in order to improve the detecting accuracy.In order to filter the background lift-off influences,the frequency spectrum and data distribution characters are utilized.As the data are detected using the eddy current array sensors,many kinds of noises would exist in the data set,such as the electromagnetic noise.Thus,a new noise-filtering algorithm based on mathematical morphology is designed.Finally,a defects localization method based on the deep traversal search algorithm is conducted.4.In chapter 5,an actual experiment of the designed detecting system is conducted in order to verify the performance of defects-localization and test-resolution through detecting the different sizes of specimens.The results show that the detecting system is capable of detecting the defects in the spinning cylinder by using the flexible eddy current array detecting technique.