Static and Dynamic Characteristics of Giant Magnetostrictive Materials under High Pre-Stress

Abstract

We describe the static and dynamic characteristics of a giant magnetostrictive material under high pre-stress, using the pre-stress given to the giant magnetostrictive material as a parameter, and also evaluate material constants. Seven evaluation units, each having an optimum magnetic bias applied to vary the pre-stress given to the material from 15 MPa to 54 MPa, were used to measure the static and dynamic characteristics. As a result, the trends of equivalent circuit constants such as stiffness, internal resistance, and force factor in response to the increase in pre-stress for enhancing the output, were clarified. Furthermore, considering the linearity to the input level, the necessity of examining the optimum pre-stress region, in addition to the simple increase in pre-stress, was suggested.

Analysis of Current Estimation along Sound-Channel Axis in Central Pacific

“…1. [2][3][4] The effects of El Nin ˜o and southern oscillation (ENSO) were considered from the water temperature distribution changes at the experimental area. 5,6) The existence of the meridian circulation between the tropical and subtropical ocean was also suggested on the basis of historical hydrographic data analysis results.…”

Fluctuation of Long-Distance Sound Propagation in the Central Pacific

“…OAT experiments extending over a long period of time were periodically performed by the Japan Agency for Marine-Earth Science and Technology (JAM-STEC) in the central equatorial Pacific from 1998 to 2000. [3][4][5][6][7][8][9][10][11][12][13][14] The main purposes of these experiments were to determine relations between water temperature and El Nin ˜o and southern oscillation (ENSO), and to observe the meridian circulation between the tropical and subtropical ocean.…”