EMAT evaluation of thin conductive sheets

Abstract

At present a non-destructive testing of conducting materials becomes very important one in connection with monitoring and control of strategic technical facilities, e.g. nuclear power plants. There are more methods of material testing and evaluation and every of them has its advantages and disadvantages. Recently the electromagnetic methods are in increasing interest. There are many ways of conducting material testing. One of them often used utilises investigation of eddy currents induced in the surface layer by means of a proper coil. The arrangement is very simple and inexpensive but it offers only local information on cracks and other inhomogeneities in the thin surface layer. On the other hand there exist a method based on an electromagnetic – acoustic transducer (EMAT), which is able to generate and detect acoustic wave in a conducting body in a contact-less way. The present paper deals with a survey of EMATs for investigation of thin metallic layers by means of Lamb waves. The new design of generation coil is presented.