Analytical model for support plate interference in eddy current tube testing
Abstract
An analytical model is developed for evaluating the eddy current signal from an inspection coil inside a tube under the area of a support plate. The electromagnetic field problem is formulated in terms of the magnetic vector potential and is solved using domain truncation and eigenfunction expansions. Closed-form expressions are derived for the coil impedance and the electromagnetic field. The support plate is effectively replaced by its own surface onto which the Leontovich impedance boundary condition is enforced. The model is quite efficient for the usual configuration that involves a non-ferromagnetic tube and a ferromagnetic support plate and its validity is verified with a commercial FEM package.
Keywords
Analytical models
Boundary value problems
Eigenvalues and eigenfunctions
Electromagnetic fields
Ferromagnetic materials
Ferromagnetism
Nondestructive examination
Closed-form expression
Eddy current signals
Eigenfunction expansions
Electromagnetic field problems
Ferromagnetic supports
Leontovich impedance
Magnetic vector potentials
Support plates
Eddy current testing