B.W. Wang

Optimization of hysteresis parameters for the Jiles-Atherton model using a genetic algorithm

A dynamic model with hysteretic nonlinearity for magnetostrictive actuators has been established, combined with the Jiles-Atherton model. The hysteresis parameters for the model have been optimized using the genetic algorithm (GA). Simulation and experimental results demonstrated the effectiveness of the model and parameter identification approach.

Hysteresis compensation for giant magnetostrictive actuators using dynamic recurrent neural network

According to the hysteresis characteristics of the giant magnetostrictive actuator (MA), a dynamic recurrent neural network (DRNN) is constructed as the inverse hysteresis model of the MA, and an on-line hysteresis compensation control strategy combining the DRNN inverse compensator and a proportional derivative (PD) controller is used for precision position tracking of the MA. Simulation results validate the excellent performances of the proposed strategy

Modeling dynamic hysteresis for giant magnetostrictive actuator using hybrid genetic algorithm

This paper establishes a simple and novel dynamic hysteresis model for giant magnetostrictive actuator by considering the eddy current loss, anomalous loss and structural dynamic mechanical behavior of the actuator. To obtain parameters of the model, a hybrid genetic algorithm is proposed. Comparisons between the experimental and calculated results show the validity and practicability of the model

Structure, Curie temperature, and magnetostriction of SmZn1−xMnx alloys

The structure, Curie temperature, and magnetostriction of SmZn1-xMnx polycrystalline crystals were investigated by x-ray diffraction, vibrating-sample magnetometer, and standard strain gauge techniques. It is found that SmZn1-xMnx alloys are nearly a single Sm(Zn,Mn) phase with the CsCl-type cubic structure up to x=0.2. The Curie temperature of SmZn1-xMnx alloys quickly increases with increasing Mn when x <= 0.05 and gradually does in the range of 0.05 < x <= 0.2. The substitution of Mn for Zn in the SmZn compound has a marked effect on improving the Curie temperature and makes it reach 255 K when x=0.2. The magnetization of SmZn1-xMnx alloys increases with increasing Mn content in the range of 0 < x <= 0.2 and the magnetostriction increases in the range of 0 < x <= 0.15. (c) 2006 American Institute of Physics.

Structure, magnetic properties, and magnetostriction of Sm0.5R0.5(Fe1−xCox)2 compounds (R=Nd,Pr)

The structure, magnetic properties, and magnetostriction of Sm0.5R0.5(Fe1−xCox)2 compounds (R=Nd,Pr) have been investigated by using x-ray diffraction analysis, ac initial susceptibility, vibrating sample magnetometer, and standard strain techniques. It was found that the (Sm0.5Nd0.5)Fe2 compound with MgCu2-type cubic structure possesses low magnetocrystalline anisotropy and high ratio of magnetostriction to magnetocrystalline anisotropy. When Co is substituted for Fe, the Curie temperature of (Sm0.5Nd0.5)(Fe1−xCox)2 alloys exhibit a peak at x=0.25 and the saturation magnetization increases with increasing Co content when x<0.25 and decreases when x⩾0.5. The microstructure of (Sm0.5Pr0.5)(Fe1−xCox)2 alloys is nearly a single phase in the range of 0.75⩽x⩽1. The saturation magnetization and magnetostrictiom of the alloys exhibit a peak at x=0.25 and x=0.5, respectively.

Magnetomechanical properties of single crystal Terfenol-D

Quasi-static and dynamic magnetomechanical measurements have been made on a twin-free oriented single crystal of Tb/sub 0.27/Dy/sub 0.73/Fe/sub 2/ (Terfenol-D). Unusually large values of dynamic strain coefficient, d/sub 33/, and magnetomechanical coupling coefficient, k/sub 33/, of 19.1 nm A/sup -1/ and 0.83 respectively were recorded with an oscillating field of amplitude 500 A m/sup -1/ rms at room temperature. The static magnetostriction saturated at 1688/spl times/10/sup -6/, however 90% of this strain was achieved with a field of 45 kA m/sup -1/. The strain versus magnetization curves exhibit unusually linear regions, allowing confirmation that 71/spl deg/ domain wall motion is primarily responsible for the high coupling coefficient of this material.

Microstructure, magnetic properties, and spontaneous magnetostriction of Tb/sub 0.2/Pr/sub 0.8/(Fe/sub 0.4/Co/sub 0.6/)/sub x/

The microstructure, magnetic properties and magnetostriction of Tb/sub 0.2/Pr/sub 0.8/(Fe/sub 0.4/Co/sub 0.6/)/sub x/ (1.65/spl les//spl times//spl les/1.90) alloys has been studied. The Curie temperatures for the 1:2 and 1:3 phases decrease with increasing x, whereas the saturation magnetization increases with increasing x. The remanent magnetization remains almost constant for all the samples and the coercivity decreases with increasing x. The spontaneous magnetostriction (/spl lambda//sub 111/) estimated from the splitting of the (440) lines is found to decrease with increasing e. The largest /spl lambda//sub 111/ recorded for Tb/sub 0.2/Pr/sub 0.8/(Fe/sub 0.4/Co/sub 0.61/)/sub 1.65/ is 2900 ppm at room temperature.

Effect of the elastic modulus of the matrix on the coupling of magnetostrictive composites

The magnetomechanical coupling coefficient, k/sub 33/, has been modeled as a function of the elastic modulus of the matrix, E/sub m/, of composite magnetostrictive materials. Measurements of k/sub 33/ have been performed by a three-parameter technique on glass-matrix Terfenol-D composites fabricated from powders heated to 700/spl deg/C in an inert atmosphere under the application of a 1-3 kN force. It is concluded that there is a value of E/sub m/ for optimum magnetomechanical performance which is dependent on the volume fraction, V/sub f/. The optimum value of E/sub m/ is close to, but less than, the elastic modulus of the magnetostrictive material.

Structure and magnetic and magnetostrictive properties of (Tb/sub 0.7/Dy/sub 0.3/)/sub 0.7/Pr/sub 0.3/(Fe/sub 1-x/Co/sub x/)/sub 1.85/ (0/spl les//spl times//spl les/0.6)

Measurements of the structure, magnetic properties, and magnetostriction were made on arc-melted polycrystalline (Tb/sub 0.7/Dy/sub 0.3/)/sub 0.7/Pr/sub 0.3/(Fe/sub 1-x/Co/sub x/)/sub 1.85/ (0/spl les//spl times//spl les/0.6) alloys by X-ray diffraction, initial susceptibility, vibrating sample magnetometry, and standard strain gauge techniques. The measurements showed that the matrix of (Tb/sub 0.7/Dy/sub 0.3/)/sub 0.7/Pr/sub 0.3/(Fe/sub 1-x/Co/sub x/)/sub 1.85/ predominantly consists of the MgCu/sub 2/-type cubic Laves phase, with a small amount of PuNi/sub 3/-type and rare-earth rich phases. The amount of (Tb,Dy,Pr)(Fe,Co)/sub 2/ in (Tb/sub 0.7/Dy/sub 0.3/)/sub 0.7/Pr/sub 0.3/(Fe/sub 1-x/Co/sub x/)/sub 1.85/ increases with increasing Co concentration and becomes almost the only phase present when x/spl ges/0.4. The lattice parameter decreases approximately linearly with increasing x from 0.7357 nm when x=0 to 0.7300 nm when x=0.6. The Curie temperature increases with increasing x from 640 K when x=0 to 677 K when x=0.3, and then decreases to 572 K when x=0.6. The saturation magnetization M/sub s/ exhibits a minimum near x=0.3. The polycrystalline magnetostriction of (Tb/sub 0.7/Dy/sub 0.3/)/sub 0.7/Pr/sub 0.3/(Fe/sub 1-x/Co/sub x/)/sub 1.85/ decreases monotonically with increasing x. There is no evidence of an anomalously large /spl lambda//sub 100/ value as is the case for other R(Fe/sub 1-x/Co/sub x/)/sub 2/ compounds.Measurements of the structure, magnetic properties, and magnetostriction were made on are-melted polycrystalline (Tb0.7Dy0.3)(0.7)TPr0.3(Fe1-xCox)1.135 (0 less than or equal to x less than or equal to 0.6) alloys by X-ray diffraction, initial susceptibility, vibrating sample magnetometry, and standard strain gauge techniques. The measurements showed that the matrix of (Tb0.7Dy0.3)(0.7)Pr-0.3(Fe1-xCox)(1.85) predominantly consists of the MgCu2-type cubic Laves phase, with a small amount of PuNi3-type and rare-earth rich phases. The amount of (Tb, Dy, Pr)(Fe, Co)(2) in (Tb0.7Dy0.3)(0.7)Pr-0.3(Fe1-xCox)(1.85) increases with increasing Co concentration and becomes almost the only phase present when x greater than or equal to 0.4. The lattice parameter decreases approximately linearly with increasing x from 0.7357 nm when x = 0 to 0.7300 nm when x = 0.6. The Curie temperature increases with increasing x from 640 K when x = 0 to 677 K when x = 0.3, and then decreases to 572 K when x = 0.6. The saturation magnetization M-s exhibits a minimum near x = 0.3. The polycrystalline magnetostriction of (Tb0.7Dy0.3)(0.7)Pr-0.3(Fe1-xCox)(1.85) decreases monotonically with increasing x. There is no evidence of an anomalously large lambda (100) value as is the case for other R(Fe1-xCox)(2) compounds.

A micro-position system of a giant magnetostrictive actuator

In this paper, a micro-position system is proposed and developed. This newly developed micro-position system contains a giant magnetostriction actuator (GMA), a digital control constant current source, a TMS320C31-based digital signal processor (DSP) position control board and a capacitive sensor. The digital control constant current source can be adjusted continuously from 0 A to 1.551 A and its resolution is up to 0.3788 mA. This micro-position system has good stability and high anti-noise ability, and can achieve 40 nm position resolution because of using the high precision capacitive sensor, the newly developed digital control constant current source and the TMS320C31-based DSP position control board.