Student: Tao Wu
Advisor: John Bowler
Title: Evaluation of Eddy-current Probe Signal Due to Cracks in Ferromagnetic Metallic Parts
Abstract: Eddy current testing to evaluate the condition of metallic parts in a fast reactor under standby conditions is challenging due to the presence of conductive coolant, for example liquid sodium. The eddy current test system should be sensitive enough to capture small signal changes and hence an advanced inspection systems is needed. We have developed new hardware and improved numerical model to predict the eddy current probe signal due to crack in metallic fast reactor parts by using volume integral equation method. Naturally, the method of moment is used to approximate the integral equation and obtain the discrete approximation of the field in the crack domain. The simple and accurate analytical method for dealing with the hyper-singularity element evaluation is also provided. An accurate controlled experiment is carried out on the ferromagnetic stainless steel slab with precision made notch to obtain reference impedance change for comparison with the theoretical model predicted results and good agreement is achieved. This computational model can be used to refine the eddy current probe design and predict the probe signal for practical test.