METHOD FOR GENERATING AND MEASURING TORSIONAL WAVES IN CYLINDRICAL STRUCTURES BY MEANS OF PROVIDING STABLE BIAS MAGNETIC FIELD, MAGNETOSTRICTIVE TRANSDUCER, AND STRUCTURAL DIAGNOSIS APPARATUS THEREOF

摘要

A method for generating and measuring torsional waves in cylindrical structures by providing a stable bias magnetic field, a magnetostrictive transducer, and a structural diagnosis apparatus thereof are provided to generate or measure the torsional waves more effectively in the cylindrical structure. A magnetostrictive transducer(130) includes at least one strip(1a,1b,1c) attached to cylindrical structures(2), an insulator disposed around the strips, a coil wound around the insulator, and a magnet(10c) to provide a bias magnetic field to the strip. The strips are attached to the cylindrical structure at a predetermined distance in the circumferential direction. One pole of the magnet approaches a first strip of the strips and the other pole of the magnet approaches a second strip. The magnet is attached to the cylindrical structure. The magnet is attached to an inner surface of the insulator. The transducer further includes a yoke to guide the contact between the magnet and the strips. The magnet is a permanent magnet(10a,10b) or an electromagnet.