Wenrong Yang

Dynamic Response of Pressure Sensor With Magnetic Liquids

This paper presents our study on differential pressure sensors realized with magnetic liquids. We illustrate our work using a ¿U¿ tube type magnetic liquid sensor model and the corresponding experimental setup. Three major efforts are: developing the mathematical model describing the dynamic characteristic of the sensor based on the first law of thermodynamics, conducting FE simulation of electromagnetic field with magnetic liquids, and performing experimental implementation and examination using a non-magnetic based differential pressure sensor purchased. Experimental observation indicates a good agreement between the step-response and random response given by the developed magnetic liquids based sensor and the purchased non-magnetic liquids based sensor.

Element-free Galerkin modeling of giant magnetostrictive thin films

A meshless method called the element-free Galerkin method (EFGM) is introduced into the calculation of magnetostrictive thin film. With the finite element method (FEM), the distortion of the elements will decrease the precision, so EFGM is used to solve this problem. Two different magnetomechanical coupling models are proposed and a thin film cantilever is simulated with these two modeling methods. At last, the results are compared with the experiment data to illustrate the performance of EFGM and the correctness of the models.

Research on Three-Dimensional Stress Distribution of Reactor Core

Gapped iron-core reactors can obtain larger inductance, but they make larger vibration and noise than other kinds of reactors. On vibration dampers, many researchers kept their eyes on vibration isolation structures or vibration isolation materials. However, they did not compute reactor core vibration under fundamental frequency voltage or harmonic one. Because stress is the inherent reason of vibration and noise, this paper proposes a finite-element model for reactor core stress calculation based on the Maxwell stress theory. The model can handle reactor exciting currents, not only fundamental frequency but also superposition of fundamental frequency with different harmonics. Because core materials have different magnetic characteristics under different excitation conditions, this paper tested multigroup H-B curves to support the simulation. Then, the finite-element method is used to calculate the magnetic field and Maxwell stress distribution. Finally, the frequency spectrum of the stress is analyzed to provide a theory basis for further analysis of vibration and noise reduction in gapped iron-core reactors.

Theoretical and experimental researches on magnetic fluid acceleration sensor

A kind of magnetic fluid acceleration sensor (MFAS) is presented in the paper, which is using the magnetic and fluid characteristic of magnetic fluid. First, the output characteristics of MFAS and its static sensitivity are analyzed based on minimum potential energy principle, the result indicates the linear relationship between output voltage and acceleration. Then, the experimental research is carried out and compared with piezoelectric acceleration sensor simultaneity based on ZJY-601A experiment platform. The output signal of MFAS is sampled and processed by the signal processing system, the output waveform demonstrate that the experimental results are both in agreement with theoretical analysis and output of piezoelectric acceleration sensor. Finally, system errors and influencing factors on measurement sensitivity are analyzed qualitative.

A Novel Sinusoidal Pressure Generator Based on Magnetic Liquid

A novel sinusoidal pressure generator with low frequency(0.1 Hz ~ 100 Hz) based on magnetic liquid is proposed in this paper. Magnetic liquid possess both magnetism characteristic of solid magnetic material and fluidity of the liquid. The magnetic liquid acts as a reciprocating piston, when it is placed in the alternating magnetic field. Based on this, we devised a setup use of magnetic liquid to generate micro differential pressure, which varies sinusoidal and has the same frequency with the exciting current. The relation between input current and output pressure was also analyzed in this paper. Magnetic field and magnetic force is calculated. Meanwhile, the experimental platform was built for testing the performance of the setup and some experimental is performed. Both the theoretical analysis and the experiment results prove that this kind of new sinusoidal pressure generator satisfies the design demand.

Dynamic Model of Giant Magnetostrictive Acceleration Sensors Including Eddy-Current Effects

Compared with other types of acceleration sensors, the rare-earth giant magnetostrictive acceleration sensors have obvious advantages. In order to analyze performance of the giant magnetostrictive acceleration sensors, this paper presents a magneto-mechanical strongly coupled dynamic model for the giant magnetostrictive acceleration sensors, which includes eddy-current effects. Using the proposed model, the time characteristic of the induced voltage for the acceleration sensors is calculated by finite element method (FED). In order to validate the presented model, an experiment of the relation between the induced voltage and time for the acceleration sensors has been done. A comparison between the calculated results and measured ones has been carried out to examine the validity of the proposed model and the FED implementation. It is found that both of them are qualitatively in an agreement. This indicates that the proposed FED model can reflect dynamic response performance of the giant magnetostrictive acceleration sensors.

Design and Experimental Study of Giant Magnetostrictive Force Sensor

A magnetostrictive force sensor was presented, which was based on the piezomagnetic effect. Relation between magnetic flux density in the gap and applied stress on the magnetostrictive force sensor was computed by the finite element method and measured. It is found that the computed result trendency is similar with the measured one. It has been proved that the giant magnetostrictive material is suitable for use in force sensor and the structural design of force sensor is valid. The effects of various factors on performance of force sensor were also analyzed

Study of Weight Functions in the Element-Free Galerkin Method

The weight function plays an important role in the performance of the element-free Galerkin Method (EFGM). It can impose a tremendous influence on the accuracy of solutions, the complexity of computation and the rate of convergence. The continuity of the weight function causes the continuity of the shape function in the EFGM. Therefore, it becomes particularly urgent to select an appropriate weight function suited to electromagnetic calculations

Dynamic modeling of a magnetic system constructed with giant magnetostrictive thin film using element-free galerkin method

A dynamic model of electromagnetic devices constructed with magnetostrictive thin film is developed to study the dynamic characteristics of the system. In the developed model, the inductance is considered as current and geometry dependent so as to represent the magneto-elastic property of the magnetostrictive thin film. Such an inductance is obtained from coupled magnetoelastic field solutions. Element-free Galerkin method (EFGM) is adopted in numerical field analysis so as to describe the magnetostrictive thin film; the DeltaE effect is considered to improve the material property modeling. The developed simulation model is examined through comparing the simulated current-voltage characteristic with the measured one

Magnetic field analysis and optimum design of adjustable magnetic liquid damper

A novel adjustable magnetic liquid damper is designed in this paper which dissipates the vibration energy by viscous flow of magnetic liquid with movement of inertia mass. Firstly, considering the viscosity of magnetic liquid and the size of the damper, the theoretical model of the magnetic mechanical coupling system is established, and the damping force of the damper can be obtained from this model. Secondly, the magnetic field distribution in the absorber is calculated by the finite element method. Based on the magneto-viscous characteristic of magnetic liquid, the numerical simulation model of the cantilever and damper system is established. The dependence of damping force on magnetic field and the size of inertial mass is analyzed. Finally, the dependence of damping force on magnetic field and the size of inertial mass is analyzed. This damper can finely adjust the damping parameters, and has good damping effect on the vibration of the spacecraft structures with low frequency and small damping.