A Perturbation Approach for the Modeling of Eddy Current Nondestructive Testing Problems With Differential Probes

Abstract

A perturbation technique applied to the finite element modelling of eddy-current nondestructive testing (ECNDT) problems is developed for taking into account differential probes. It concerns a h−conform formulation. The source term of the formulation is directly determined by the projection of the unperturbed field in a relatively small region around the defect. The voltage change due to the presence of the flaw is calculated by performing an integral over the defect and a layer of elements in the exterior domain that touch its boundary. The considered test case involves a shielded differential probe scanning the surface of a metal specimen for the detection of flaws.

Perturbation Finite Element Method for Efficient Copper Losses Calculation in Switched Reluctance Machines

“…Once it is solved, we pick up the information on the slot boundary, from which either the vector potential or its normal derivative are applied as Dirichlet or Neumann BC respectively to the slot subdomains where we integrate the real investigated winding configurations of conductivity . Accordingly, the proposed model reduction consists in solving the problem only in the slots' subdomains where the solutions are called perturbations [3,4].…”

“…Particularly in this paper, we are interested in the strong influence of the coil geometric disposition in machine slots on the level of eddy current losses dissipated in the windings of switched reluctance machines (SRM). To shorten the calculation time while selecting by means of FE analyses the optimal winding configuration, this paper suggests a model reduction technique which is akin to perturbation FE method [3,4]. It profits from only one approximate full FE solution based on a uniform current density, a simplified winding and a coarse mesh model to find fast solutions in the slots subdomains when any variation of winding geometrical or physical data occurs.…”

Exploitation of independent stator and rotor geometrical periodicities in electrical machines using the Schur complement

“…These can be a-posteriori model reduction techniques like proper orthogonal decomposition [1] and perturbation zooming methods [2] or a-priori reduction techniques like the ones dealing with the magnetic symmetry or further geometrical periodicity exhibited in most rotating electrical machines [3] [4] [5].…”

Finite-Element Model Reduction of Surface-Mounted Permanent Magnet Machines by Exploitation of Geometrical Periodicity

“…To tackle this issue, model reduction techniques are widely used; they have shown their efficiency in reducing both computational time and memory storage requirements. Some of these model reduction techniques are based on the subdomain reduction, namely, the ones dealing with the perturbation principle [3], [4]; they are usually used to determine the solution only in the most relevant areas. Besides, other techniques are dealing with the order reduction of the equation system.…”