Electromagnetic methods of defect detection

An introduction to the topic of detecting and characterizing defects in materials nondestructively by electromagnetic methods is presented. It is noted that all such methods rely for their operation on the interaction of an electromagnetic field with the structure under test and can thus be classified as elliptic, parabolic, or hyperbolic depending upon the governing partial differential equation type describing the underlying physics. This classification has particular significance for modeling studies based on finite-element or boundary-integral analysis and also affects the solutions of the corresponding inverse or defect characterization problem. Particular attention is given to static and quasi-static field NDE (nondestructive evaluation) methods and to wave-based NDE methods. It is concluded that, although finite-element and boundary-integral solutions will separately continue to provide additional physical insight into specific NDE phenomena, it is quite possible that a hybrid approach will be necessary to integrate NDE modeling techniques successfully into the interactive, computer-based product design environment