直流ポテンシャル法による表面き裂形状の検出

概要

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Feasibility of DC potential technique for monitoring surface cracks was discussed by applying the reversing DC potential method to the plates with a simulated surface crack. Disturbance of electrical field occurred near the crack. Then the sensitivity of the crack measurement rapidly decreased with the distance of measuring position from the crack. Less than a half of the plate thickness was desirable as the measuring distance. Although the potential difference depended on the crack aspect ratio a/c, the crack area could be estimated from the potential ratio at the crack center. The potential distribution along the crack almost corresponded to the crack shape. A lack of singularity at the crack tip on the surface, however, made it difficult to determine the crack tip position. By using a proportional relation between the potential ratio V/V_0 and the crack depth a/t, and by assuming that a surface crack takes a semi-circular configuration, the crack length c on the surface and the crack depth can be estimated. The optimum method to determine the crack shape is to repeat the finite element analysis until the potential obtained analytically coincides with that obtained experimentally.
社団法人日本材料学会の論文
1984-05-15