Analysis of Eddy Current Distribution and Resulting Flaw Detection Mechanism for Self-Nulling Probe

Thumbnail Image
Date
1995
Authors
Wincheski, Buzz
Fulton, Jim
Nath, Shridhar
Namkung, Min
Major Professor
Advisor
Committee Member
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract

The Self-Nulling Probe developed at NASA-LaRC has been previously shown to simplify inspections and increase detectability of surface and subsurface flaws in conductive materials [1]. The operation of the probe has been explained in terms of a redistribution of the eddy currents and associated magnetic field by the presence of inhomogeneities in the test article [1, 2]. In the present work a mathematical model is introduced to calculate the eddy current flow induced by the Self-Nulling Probe in test samples containing through notch flaws. The model combines axisymmetric finite element modeling (FEM) with con-formal mapping techniques in order to calculate the stream function of the induced current flow about arbitrarily sized and positioned notches. Physical parameters such as the induced eddy current density, magnetic field normal to the surface of the sample, and probe output voltage are then calculated from the stream function of the induced current flow. Simulation results are compared with experimental measurements taken on calibration standards with good agreement.

Series Number
Journal Issue
Is Version Of
Versions
Academic or Administrative Unit
Type
event
Comments
Rights Statement
Copyright
Sun Jan 01 00:00:00 UTC 1995
Funding
DOI
Supplemental Resources