Influence of the different kinds of magnetic fields on the magnetomechanical damping of high-purity iron

Abstract

The magnetomechanical damping Q mag−1 of high purity iron is measured as function of the amplitude of an alternating shear strain γ (frequency ≈ 1 Hz) in presence of a longitudinal magnetic field H. Successively the influence of a dc magnetic field and of ac magnetic fields of frequencies either equal (synchronous field) or very great (50 Hz) compared to that of the mechanical oscillations are considered. The variation of Q mag−1 = f(γ) exhibits a maximum; the evolution of this maximum is followed as function of the intensity of H. At small values of H and for the three magnetic fields, first an increase is noted of the intensity of the maximum followed by a decrease at higher values of H. In order to explain the experimental results, the energetic conditions of jumps of 90° magnetic domain walls are studied, in the field of force in which they are moving. The applied magnetic field plays two opposed parts: one favouring the other stabilizing the irreversible jumps which are induced by the mechanical alternating stress. The dc field and ac 50 Hz field have these two roles whereas the synchronous field exerts nearly only an initiating role.

Elastic properties of magnetostrictive thin films using bending and torsion resonances of a bimorph

“…20͒. Although two main theoretical models have already been derived, 22,23 further work is needed to see whether these models also apply to thin film materials. Finally, it is worth commenting on the pole effect: 15 it is due to the magnetostatic restoring force on the cantilever that arises when the field is along the cantilever axis.…”

Study of damping capacity of Fe–5.4Al–0.05Ti alloy

“…It is believed that the hysteresis losses are caused by rotation or movement of 90 domain walls but not by 180 domains [19,20]. Pulino-Sagradi et al [17] reported that the damping capacity enhances as the volume-fraction of 90 domains increases.…”

Magnetomechanical damping in plasma sprayed iron–chromium based coatings

“…[1][2][3][4][5] The mechanisms of such a damping have been mainly associated with the stress-induced movements of domain walls and related phenomena. [6][7][8][9][10] There are phenomenologically three contributions recognized which dissipate mechanical energy upon application of a cyclical stress. First, the hysteresis damping which is related to the irreversible movement of domain walls.…”

“…First, the hysteresis damping which is related to the irreversible movement of domain walls. 6,7 Second, the macro eddy current damping which arises form the bulk response to a change in magnetic flux across the vibrating specimen. 8,9 Third, the micro eddy current loss which is generated from the local changes of magnetization due to any displacement of domain boundaries.…”

“…9,10 It is believed that, in general, all three loss mechanisms can operate simultaneously, but their relative importance depends on the material properties such as residual stress and magnetization, as well as on the experimental conditions including vibration frequency and amplitude. 9 These behaviors have been experimentally investigated in both crystalline 6 and amorphous 11 ferromagnetic materials and successfully used to develop the vibration damping alloys for high strength engineering applications. [12][13][14][15][16] Among the magneto-mechanical damping materials, the high chromium ferritic steels have been particularly considered because of their elevated mechanical properties and good corrosion resistance.…”