Boundary Element Method Based Probe Design Model Validation

The inspection of aircraft engine components using eddy current (EC) techniques has played a vital role in the nondestructive evaluation industry. The objective of the inspection is to determine the structural integrity of the components in a noninvasive manner. The effectiveness of an EC probe design is often evaluated in terms of the probability of detection (POD) of flaws. Many factors need to be considered when estimating the POD. These factors include scan and index spacings, operating frequencies, and flaw morphologies. Traditionally, the EC probe design cycle is iteratively performed experimentally until one either meets or exceeds the minimum required POD. Undoubtedly, this is a time consuming and expensive process since a new probe has to be constructed and tested every time the design is changed. A more sensible approach is to numerically simulate the functionality of probes so design improvements can be done iteratively using a computer under a CAD environment. The numerical probe design model is developed using the boundary integral equation (BIE) approach. By solving the BIEs numerically using the boundary element method (BEM), electromagnetic fields produced by the EC probes can be easily obtained through simple numerical integration