マルチターミナルポテンシャル法による片側貫通き裂の検出に関する有限要素法による検討

抄録

The direct current potential drop method for on-line monitoring of side edge cracks was studied. In a plate with a single edge crack, the measured potential difference varies with crack position. Based on the distinctive distribution of potential difference, a multi-terminal DC potential technique was proposed for detecting crack length and position. In this technique, many potential difference measuring electrodes with the same spacing are fixed on the plate side. By comparing the many potential differences, the crack length and position can be calculated. The electrical field was analyzed by FEM, and the calibration curve and sensitivity were examined. The analyzed potential differences were classified based on the position. V₁ is the potential difference between the electrode pair with a crack. V₂ and V₃ are the potential differences between electrode pairs without a crack, and are on either side of the V₁ obtained electrode pair. V₂ is closer to the crack than V₃. V₀ is the reference potential difference obtained by averaging the potential differences except V₁, V₂ and V₃. The analysis shows that the potential difference ratio (V₁+V₂-V₀)/V₀ gives the accurate crack length, the difference of V₂ and V₃ gives the accurate crack position, and the sum of V₂ and V₃ gives the side on which the crack exists, that is, the surface or reverse-face.