Magnetostrictive and Kinematic Model Considering the Dynamic Hysteresis and Energy Loss for GMA

Due to the influence of magnetic hysteresis and energy loss inherent in giant magnetostrictive materials （GMM）, output displacement accuracy of giant magnetostrictive actuator （GMA） can not meet the precision and ultra precision machining. Using a GMM rod as the core driving element, a GMA which may be used in the field of precision and ultra precision drive engineering is designed through modular design method. Based on the Armstrong theory and elastic Gibbs free energy theory, a nonlinear magnetostriction model which considers magnetic hysteresis and energy loss characteristics is established. Moreover, the mechanical system differential equation model for GMA is established by utilizing D＇Alembert＇s principle. Experimental results show that the model can preferably predict magnetization property, magnetic potential orientation, energy loss for GMM. It is also able to describe magnetostrictive elongation and output displacement of GMA. Research results will provide a theoretical basis for solving the dynamic magnetic hysteresis, energy loss and working precision for GMA fundamentally.

Enhanced Magnetostriction of a Narrow Hysteresis Tb_(0.26)Dy_(0.54)Ho_(0.20)Fe_2 Alloy

In this work, a magnetic annealing method used to enhance the magnetostrictive property of a narrow hysteresis alloy Tb0.26Dyo.saHo0.20Fe2 is reported. Cylindrical-rod shaped specimen with 〈110〉 crystal orientation was fabricated using zone-melting unidirectional solidification technique, followed by annealing in a transverse magnetic field of 366 kA/m. The crystal orientation and bi-phase solidified morphology can be retained after magnetic annealing. A high magnetostriction of 1.508×10^-3 was obtained in the magnetically annealed specimen, which is 25.2% larger than the untreated one. Simultaneously, the magnetostriction hysteresis width is slightly enlarged from 4.45 to 6.36 kA/m, which is still much lower than that of the Ho-free Tbo.3Dy0.TFe2 alloy. The additional anisotropy which is induced by magnetic annealing, as reflected by the magnetic hysteresis loops, is responsible for the enhancement of magnetostrictive performance.

Magnetostriction and hysteresis of <110> oriented TbDyHoFe_(1.95) alloy

(Tb0.36Dy0.64)1-xHoxFe1.95 magnetostrictive alloys with 【110】 orientation were prepared by zone melting directionally solidified method.The magnetostrictive performance and hysteresis of 【110】 aligned polycrystalline(Tb0.36Dy0 64)1-xHoxFe1.95 were investigated under applied magnetic field H(0【H【4 kOe) in the temperature range from-60 to 80 oC with 0,5 and 10 MPa pre-stress.The(Tb0.36Dy0.64)1-x HoxFe1.95 alloys(x【0.3) have the character of giant magnetostriction from-60 to 80 oC.An obvious magnetostrictive "jump" effect was observed in these samples from-60 to 80 oC.The pre-stress and temperature dependence of the Wh was also examined.Between the temperature range from-60 to 80 oC,the magnetostriction increased with temperature decreased,while the magnetostriction hysteresis decreased,with the pre-stress increased,but the magnetostriction and the magnetostrictive hysteresis increased.