| 摘要 |
PROBLEM TO BE SOLVED: To measure not only the stress of an elastic area but the stress of a plastic area, exceeding a yield point by plastically deforming part of a Barkhausen noise detect part of a steel material, applying residual stress and detecting Barkhausen noises generated from the part. SOLUTION: When a compressive residual stress -σγis applied in an in-plane direction of a Barkhausen noise measurement part of a steel material with a tensile yield stressσty, an external stress F in the range of 0<=F+σty can be diagnosed. When a tensile residual stressσγ(>0) is applied in the in-plane direction of a measurement face of the Barkhausen noise measurement part of a steel material with a compressive yield stress -σcy (σcy>0), the external force F in the range of -(σγ+σcy)<=F<=0 can be diagnosed. At this time, linear correlation range of a calibration curve increases as the residual stressσγbecomes larger, so that the external stress F can be diagnosed up to a larger value.
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