Finite element procedures were used to discuss the practicality of the electrical potential technique for monitoring the surface crack of a plate.
The analysis applied to solve the potential field problems involves the solution of Laplace equation. Analytical figures were modeled as three-dimensional bodies using eight-nodes isoparametric elements. A computer program ADINAT was employed in this study.
From finite element analyses, the following method of determining surface crack configuration was proposed. The electrical potential ratio is determined first at several positions from a crack center and the relationship between electrical potential ratio and distance from a crack center is obtained. By assuming that a surface crack takes a half elliptical configuration, the crack length c at surface can be estimated from the relation between the crack area ratio and the distribution of electrical potential ratio from a crack center. Then the crack depth a can be decided from the distribution of normalized electrical potential ratio.
