| 摘要 |
PURPOSE:To eliminate the need for an exciting coil by winding a coil around an anode-cathod type probe formed by winding a coil around a ferromagnetic body and a test body or jig, test-piece, etc., and measuring strain at the time of an impact. CONSTITUTION:When an impact 2 is applied to the ferromagnetic body, the longitudinal wave of an elastic body propagate as a compressional wave while accompanies by variation in volume due to expansion and contraction. At this time, the ferromagenetic body is magnetized in the propagation direction of the elastic wave by the reverse effect of magneto-striction to produce magnetic flux in a round bar 1 made of the ferromagnetic body. This magenetic flux is proportional to the intensity of the impact force. Then, a voltage having a speed proportional to variation of magenetic flux penetrating the coil 3 is induced according to the Faraday rule. Thus, variation of the compressional wave of the elastic wave itself is detected to eleminate the problem of follow-up property, eliminating the need for the exciting coil. |
