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Magnetostrictive Bimaterial Elements

IP.com Disclosure Number: IPCOM000053173D
Original Publication Date: 1981-Sep-01
Included in the Prior Art Database: 2005-Feb-12
Document File: 3 page(s) / 32K

Publishing Venue

IBM

Related People

Nayak, JH: AUTHOR

Abstract

This proposal relates to the bonding or connecting of two materials of widely differing magnetostriction coefficients. Such a bonding or connection mechanically amplifies the magnetostrictive deformation and renders it more useful for practical applications.

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Magnetostrictive Bimaterial Elements

This proposal relates to the bonding or connecting of two materials of widely differing magnetostriction coefficients. Such a bonding or connection mechanically amplifies the magnetostrictive deformation and renders it more useful for practical applications.

Coefficients of magnetostriction for commercially available magnetostrictive materials are generally in the range of +70 to -33 x 10/-6/ inch/inch [1]. These deformations are small for the purposes of direct applications in devices. Consequently, magnetostrictivc effect has so far been applied only in a few devices, such as ultrabonic vibrators, detectors and filters [2].

Let A and B be two materials of widely differing magnetostrictive coefficients. A strip of material A is bonded to a strip of material B, as shown in Fig. 1. This bimaterial strip, when fixed at one end, deflects laterally by an amount d under the action of an axial magnetic field, as seen in Fig. 2.

The deformation d is larger than the difference in change in length of A and B by a factor kappa L/h, where L is the length and kappa is the net thickness (L>>kappa). The constant kappa depends on the end conditions. Timoshenko
[3] has analyzed such deformations for thermostatic bimaterials. This analysis can be extended to the case of magnetostrictive bimaterials.

A closed structure can be used to provide a closed magnetic flux path. Passing a current through a conductor wound on a portion of this closed structure creates the necessary magnetic field to control the deformation.

Examples of such closed structure magnetostrictive bimaterial elements are shown in Figs. 3-9. Preferably, material A will have a large +ve magnetostriction coefficient, and material B a large -ve coefficient. Material C should have near zero magnetostriction...