| 摘要 |
PURPOSE:To predict the extent of deterioration of the equipment to be measured from its initial state nondestructively with high accuracy by estimating the maximum and minimum values of the whole equipment according to the statistical distribution of extremal values of variation measurements of magnetic characteristics at optional positions of the equipment. CONSTITUTION:The deterioration of a metallic material is inspected. In this case, the body 1 and a reference test-piece 15 are applied with exciting magnetic fields of desired frequency with sine waves from exciting coils 5A and 5B, Hall elements 2A and 2B detect the values of the magnetic fields, and detection coils 3A and 3B detect the magnetic field density. Thus, a discontinuous jump of extremely small magnetism based upon a magnetic hysteresis curve and Barkhausen effect generated by the movement of a magnetic wall is measured. Consequently, physical characteristics for deciding the extent of deterioration are found at the optional positions. A regression period based upon the statistical distribution of the extremely values of measured value is used to estimate the maximum and minimum values of the physical characteristics from the measured value and the maximum value of the deterioration of the measured body 1 is estimated from a data base for the relation between the deterioration extent and characteristics of a material which is already found. |
