Electric Potential CT Method for Measuring Location and Size of Two-and Three-Dimensional Cracks : Development of Boundary Element Inverse Analysis Method for Electric Potential Problems and Its Application to Non-Destructive Crack Measurement

Abstract

An electric potential CT (Computer Tomography) method was proposed, in which data on electric potential distribution were computer-processed by inverse analysis to estimate location, shape and size of two-and three-dimensional cracks. Two inverse analysis schemes were formulated in terms of the boundary element equations In one scheme the boundary integral equations were solved for quantities on unprescribed boundaries. Cracks were identified as flux-free boundaries. In the other scheme the boundary element solution of electric potential for an assumed crack profile was compared on free boundaries with the observed values. The crack profile which minimized the square sum of residuals, was employed as the most probable one. Computer simulations of measuring locations and sizes of several types of two-dimensional cracks demonstrated potential of the proposed CT method.