Numerical modeling of thermal fatigue cracks from the viewpoint of eddy current testing
遊佐 訓孝 Noritaka YUSA 橋爪 秀利 Hidetoshi HASHIZUME Iikka VIRKKUNEN Mika KEMPPAINEN
conductivity electromagnetic nondestructive evaluation finite element method numerical simulation
Abstract. This study discusses a suitable numerical modeling of a thermal fatigue crack from the viewpoint of eddy current testing. Five artificial thermal fatigue cracks, introduced into type 304L austenitic stainless steel plates with a thickness of 25 mm, are prepared; and eddy current inspections are carried out to gather signals using an absolute type pancake probe and a differential type plus point probe. Finite element simulations are then carried out to evaluate a proper numerical model of the thermal fatigue cracks. In the finite element simulations, the thermal fatigue cracks are modeled as a semi-elliptic planar region on the basis of the results of the destructive tests. The width and internal conductivity are evaluated by the simulations. The results of the simulations reveal that the thermal fatigue cracks are regarded as almost nonconductive when the internal conductivity is assumed to be uniform inside.