A boundary element formulation for thin shell problems

With time harmonic eddy current problems, surface impedance approaches have been successfully applied. The surface impedance techniques are warranted in eddy current applications due to the fact that the rate of change of the field normal to the conductor is guaranteed to dominate over the tangential gradients. The analysis of thin iron shells has classically been problematic due to cancellation errors across the thickness of the shells. A boundary element formulation is developed which eliminates the volume of the shell. The collapsed interface is assumed to contain both single and double layer surface currents to represent their field contribution in all of space. The double layer currents accurately simulate the channeling of flux into the shell. The single layer surface currents accurately reflect the thin shell's perturbation to the field far from the shell. A thin shell cylinder and sphere serve as the test body against which the formulation's predictions are compared for a variety of element densities.