| 摘要 |
PURPOSE:To inspect the stress or fatigue deformation of ferromagnetic material by utilizing the relation between the high frequency component of an electromagnetic wave generated in the process of magnetizing the ferromagnetic material and the high frequency component of an elastic wave, and the correlation with its stress, etc. CONSTITUTION:The magnetic circuit device is composed of a laminated iron core 2, exciting coil 3, and AC power source 4 opposite to the material 1 to be inspected. An inspecting device consists of a BN (Barkhausen noise) coil sensor 7 installed near the surface of the material 1 without contacting and an AE (acoustic emission) sensor 8 installed in contact, with the material 1. The BN coil sensor 7 outputs a signal having a voltage proportional to the magnetic flux density of the section of a detection coil and the AE sensor 8 is a piezoelectric element which measures the elastic wave. The measurement result applied to the detection of uniaxial stress in case of external stress is varied to an iron steel material having positive magneto-striction shows that the simultaneous measurement of the BN and AE signals provides the accurate estimation of a stress state. |
