Wenmei Huang

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.

Dynamic Strain Model With Eddy Current Effects for Giant Magnetostrictive Transducer

Based on the Jiles-Atherton model and transducers structural dynamics principle, the magnetoelastic dynamic strain model of giant magnetostrictive transducer is founded. This model takes into account the eddy current losses and the variety of stress. Simulation results are in a good agreement with the experimental ones. This indicates that the dynamic strain model can characterize the magnetization intensity and strain behavior at different frequency. The proposed model is suitable to describe the relation between the applied field and the output vibration at a wide range of exciting frequency

Hybrid genetic algorithms for parameter identification of a hysteresis model of magnetostrictive actuators

In this paper, we present an improved hysteresis model for magnetostrictive actuators. To obtain optimal parameters of the model, we study two distinct hybrid strategies: namely, employing a gradient algorithm as a local search operation of a genetic algorithm (GA), and taking the best individual of a GA as the initial value of a gradient algorithm. Here, two different gradient algorithms, a well-known Levenberg-Marquardt algorithm (LMA) and a novel Trust-Region algorithm (TRA), are investigated. Finally, the proposed four hybrid genetic algorithms (HGAs) are applied to identify parameters of the improved model. The simulation and experimental results show the performances of the HGAs and the improved hysteresis model.

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

A numerical model of displacement for giant magnetostrictive actuator

A numerical model of displacement for a giant magnetostrictive actuator was founded. According to the model and the measured magnetic characteristic of giant magnetostrictive material, the relation between input current and output displacement for the actuator was calculated by means of the finite element method. A comparison between the calculating result and experimental one for the actuator was carried out and it was found that they were in agreement well. This demonstrates that the numerical model can be used for the design of giant magnetostrictive actuators.

Dynamic Experiments of Strain and Magnetic Field for Galfenol Rod and Its Modeling

Dynamic actuation experiments of an Fe83Ga17 (Galfenol) rod sample were conducted by the authors. A permanent magnet was used to apply a 2.25-kA/m bias field. Dynamic current through the excitation coils was applied to obtain a dynamic magnetic field. The frequencies of the dynamic field are 1, 10, 20, 40, 60, 100, 200, and 300 Hz. Hysteresis between the strain and dynamic magnetic field increases with increasing frequency. The power losses consist of hysteresis loss, classical eddy current loss, and anomalous (or excess) loss when Galfenol is excited by a dynamic field. To describe the hysteresis, a dynamic hysteresis model of Galfenol based on the energy-weighted average hysteresis equation, eddy current loss, and anomalous loss was used. The hysteresis loss was calculated using incremental volume fractions, which was evaluated using the energy-weighted average formula. The experimental results and model calculations agree well for frequencies below 200 Hz. The model can be used to guide the design of Galfenol dynamic applications in low frequency such as actuators and vibrators.

The magnetostriction and its ratio to hysteresis for Tb-Dy-Ho-Fe alloys

The x(Tb0.15Ho0.85Fe2) + (1 − x)(Tb0.3Dy0.7Fe2) alloys were prepared in an arc furnace under high purity argon. The as-cast samples wrapped in Mo foil were sealed in a silica tube filled with high purity argon. The static measurement of magnetostriction (λ//, λ⊥) was made by standard strain gauge, and the magnetization M was measured by a vibrating sample magnetometer. It is found that the magnetostriction λ// of x(Tb0.15Ho0.85Fe2) + (1 − x)(Tb0.3Dy0.7Fe2) alloys decreases with increasing x and it does from 880 × 10−6 for x = 0 to 210 × 10−6 for x = 0.9 at the magnetic field of 640 kA/m. The ratio (λ///Wh) of magnetostriction to hysteresis exhibits a peak when x = 0.1, and it means that the Tb0.285Dy0.63Ho0.085Fe2 (x = 0.1) alloy possesses both large magnetostriction and small magnetostrictive hysteresis.

Magneto-thermo-mechanical characterization of giant magnetostrictive materials

The variations of magnetization and magnetostriction with temperature and stress were investigated through the analysis of the effective field, induced by temperature and stress. A nonlinear magnetostrictive model of giant magnetostrictive materials was proposed. The proposed model can be used to calculate the magnetostrictive characterization of giant magnetostrictive materials in different temperatures and under different stresses. The coupling effects of axial stress, magnetic field, and temperature on the magnetostriction of a Terfenol-D rod were numerically simulated as well as experimentally tested. Comparison between the calculating and experimental results shows that the proposed model can better describe the magneto-thermo-mechanical characteristics of Terfenol-D rod under different temperatures and compressive stress. Therefore, the proposed model possesses an important significance for the design of magnetostrictive devices.

Large current measurements using a fibre optics current sensor

An optical ac-current sensor with large range and high accuracy is designed, which is based on magnetostriction effect and fiber-loop cavity ring-down technique. The model of the sensor is proposed which described the relationship of current, magnetic field, strain and ring-down time of the fiber loop. Simulation results show that both the measurement range and accuracy of the sensor are depended on prestress. The sensor is capable of measuring ac currents in the 2-50kA and the best resolution upto 0.1 A. The analysis of materials characterization and modeling can support the actual design process.