| 摘要 |
PURPOSE:To efficiently detect only a torsional elastic wave (transversal wave) propagated in a magnetostrictive line in a noncontact state by inserting and arranging a torsional elastic wave receiving coil at the specific position of the magnetostrictive line in the noncontact state, and arranging a deviated magnet which produces a deviated magnetic field in the vicinity of the coil. CONSTITUTION:The magnetostrictive line 1 is inserted into a nonmagnetic and conductive external cylinder 12, whose left end part is fitted and fixed to a coil holder 13. A movable permanent magnet 2 is fitted slidably onto the outer periphery of the external cylinder 12. Then two torsional elastic wave receiving coils 15 and 16 are fixed in the coil holder 13. The coils 15 and 16 are fitted onto the strain line 1 without contacting and detect the transversal wave propagated through the strain line 1 by differential amplification. Further, the deviated permanent magnet 17 is fixed slantingly nearby the coils 15 and 16 and its deviated magnetic field is nearly coincident with the direction of magnetism variation caused by the transversal wave propagated through the magnetostrictive line 1. This constitution suppresses a longitudinal wave to an extent where it can be ignored substantially and only the transversal wave is emphasized and detected.
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