Novel mechanism for boring non-cylinder piston pinhole based on giant magnetostrictive materials

To bear more loads for heavy truck pistons, the shape of heavy truck piston pinhole is often designed as noncylinder form. Current methods cannot meet the needs for precision machining on non-cylinder piston pinhole （NCPPH）. A novel mechanism based on giant magnetostrictive materials （GMM） is presented. New models are established for the servo mechanism, GMM, and magnetizing force of the control solenoid to characterize the relationship between the control current of the solenoid and the displacement of the giant magnetostrictive actuator （GMA）. Experiments show that the novel mechanism can meet the needs to perform fine machining on NCPPH effectively.

Tailoring coercive field in rare earth giant magnetostrictive materials byα-Fe precipitation

Rare earth giant magnetostrictive materials(GMMs)Tb_(1-x)Dy_(x)Fe_(2±δ)(Tb-Dy-Fe)have been successfully employed in many microelectromechanical devices due to their excellent magnetostrictive properties at room temperature.However,Tb-Dy-Fe still shows a relatively large coercivity with high hysteresis,which inevitably limits its application range.Herein,micromagnetic simulations are performed to investigate the size effect of precipitated phase(α-Fe)on coercivity in Tb-Dy-Fe.Simulation results demonstrate that the coercivity is reduced from 31.46 to 12.48 mT with increasing the size ofα-Fe from 4 to 50 nm in Tb-Dy-Fe since the precipitated phase ofα-Fe can act as a magnetization reversal nucleus.This decreasing trend of coercivity can be well fitted with an inverse square relationship,which agrees well with the nucleation theory.Our study highlights that the coercivity of Tb-Dy-Fe can be tailored by tuning the size ofα-Fe precipitation.

Giant Magnetostrictive Material Loudspeaker System Acoustic Radiation Simulation

An infinite panel model of giant magnetostrictive material loudspeaker system （GMMLS） is proposed by making use of finite element method（FEM）. Bending wave eigenfunction is introduced to describe the acoustic radiation condition of the panel. Far-field response in different conditions is calculated by changing the mass surface density. Conclusion is obtained by analyzing the curves simulated, that panel which has larger mass surface density can hardly generate far-field acoustic radiation for lower frequency, while the panel has smaller mass surface density generates far-field acoustic radiation for lower frequency evenly and stronger.

Giant Magnetostrictive Material Exciter for Panel Loudspeaker

The exciter component in a panel loudspeaker has a profound effect on the overall performance of the system. The equivalent circuit analysis of the combination of giant magnetostrictive material exciter and distributed mode panel is introduced and how exciter parameters influence panel lo＇udspeaker＇ s performance is discussed. Numerical predictions are given in order to show how these influences are manifested.

VIBRATION SUPPRESSION OF CANTILEVER LAMINATED COMPOSITE PLATE WITH NONLINEAR GIANT MAGNETOSTRICTIVE MATERIAL LAYERS

In this paper, a nonlinear and coupled constitutive model for giant magnetostrictive materials （GMM） is employed to predict the active vibration suppression process of cantilever laminated composite plate with GMM layers. The nonlinear and coupled constitutive model has great advantages in demonstrating the inherent and complicated nonlinearities of GMM in re- sponse to applied magnetic field under variable bias conditions （pre-stress and bias magnetic field）. The Hamilton principle is used to derive the nonlinear and coupled governing differential equation for a cantilever laminated composite plate with GMM layers. The derived equation is handled by the finite element method （FEM） in space domain, and solved with Newmark method and an iteration process in time domain. The numerical simulation results indicate that the proposed active control system by embedding GMM layers in cantilever laminated composite plate can efficiently suppress vibrations under variable bias conditions. The effects of embedded placement of GMM layers and control gain on vibration suppression are discussed respectively in detail.

FEM COUPLING FIELD ITERATION AND ITS CONVERGENCE FOR A GMM ACTURATOR

The coupling iteration (CI) of the finite element method(FEM) is used to simulate the magnetic and mechanical characteristics for a GMM actuator. The convergent ability under different prestress and different load types is investigated. Then the calculated deformations are compared with the experimental values. The results convince that the CI of FEM is suitable for the simulation of energy coupling and transformation mechanism of the GMM. At last, the output deformation properties are studied under different input currents, showing that there is a good compromise between good linearity and large strain under the prestress 6 MPa.

Magnetic Properties and Phase Transformation of Tb_(1-x)Pr_xFe_(1.96)(x=0 to 0.7) Compounds

The magnetic properties and the phase Transformation of Tb1-xPrx Fe1.96（x = 0 to 0.7） compounds were studied by means of vibrating sample magnetometer（VSM）, X-ray diffraction（XRD） and SEM back-scattered electron （BSE）. The result indicates that the saturation magnetization σs of compounds along an easy axis decreases with the addition of Pr contents, which reduces from 77.24 Am^2·kg^-1（x =0） to 11.84 Am^2·kg^-1（x =0.5） and then returns to 37.14 Am2·kg^-1 （ x = 0.7）. The non-cubic phases appear when x exceeds 0.2, and the matrix of Tb1-xPrxFe1.96 compounds changes from （Tb, Pr）Fe2 phase with x = 0 to （Tb, Pr）Fe3 phase with x = 0.4, and at last to （Tb, Pr）2Fe17 phase in Tb0.3Pr0.7Fe1.96. Moreover, the structure, of the compounds may become more complex with the increase of Pr content.