Conductivity and Side-Length Measurement of Square Metallic Plates With Finite Dimension Based on Eddy Current Method

The classic Dodd and Deeds model has been applied to estimate the electromagnetic properties of samples in eddy current testing (ECT). In fact, the model is only suitable for the condition that sample is much larger than the radius of coil (generally speaking, three-five times larger). However, the dimension of the samples cannot meet the condition in some practical applications. This article first investigated the modified analytical solution for square metallic plates with finite dimension based on Dodd and Deeds, of which the lower limit of integral changes from 0 to a value related with the side length of square sample. Furthermore, the modified truncated region eigenfunction expansion (TREE) analytical is also established for finite square plate by truncating the range of eigenvalues. Based on the modified analytical solution, the conductivity and side length measurement of square metallic plates with finite dimension has been presented. The experiments have been carried out to verify the conductivity and side length measurement method, and the results show the average errors are only 2.3% and 0.9%, respectively.