Giant Magnetostrictive Rod Research Articles

Structure design and parameter optimization of GMA for ball screw pre-tightening

GMA (Giant Magnetostrictive Actuator) is used for ball screw pre-tightening in this paper. Compared with conventional electrostrictive actuator, GMA has greater output force, energy and strain, and it can achieve electric–magnetic-mechanical energy conversion. GM rod (Giant Magnetostrictive rod), which is a core component of GMA, is driven by the magnetic field of excitation coil to produce magnetostriction, thus a force (or displacement) is output to be used for ball screw pre-tightening. The designed GMA can output a force of about 1100 N and a displacement of about 100 μm. In order to make the excitation magnetic field intensity meet GMA’s work demand, this paper focuses on the structure design and parameter optimization of GMA, including GM rod, excitation coil, bias magnetic field and pre-compression device. GMA’s no-load displacement output experiment and the ball screw pre-tightening experiment were conducted, and the results show that the designed GMA can be used for ball screw pre-tightening through structure design and parameter optimization.

Dynamic Performance study of Giant Magnetostrictive Actuator

Optimized design problems for giant magnetostrictive actuator (GMA) structures, the effects of structural dimensions on dynamic properties of GMA were analyzed. In this paper, an equivalent dynamic model of GMA was established, and the step response and frequency response of GMA were simulated and analyzed. The results show that the length of the giant magnetostrictive rod and the mass of the load have great influence on the dynamic performance of the GMA system.

Temperature compensation design and experiment for a giant magnetostrictive actuator

Because the performance of giant magnetostrictive materials (GMMs) can vary at different temperatures, the positioning accuracy of a giant magnetostrictive actuator is affected by heat. In this work, a new simplified control strategy under compulsory water cooling is proposed to maintain a constant GMM temperature. Based on this strategy, a coupled turbulent flow field and temperature field finite element model is created for a GMM smart component. The model is simulated using COMSOL Multiphysics software version 5.3. Through simulations, the temperature field distribution of GMM smart components is analysed under different drive input currents and cooling water flow rates. Based on the obtained simulation results, a GMM intelligent component temperature control device is constructed. The experimental results are in good agreement with the simulation results; a thermostatic control effect is achieved in the thermostat of the giant magnetostrictive rod. Thus, the proposed temperature control strategy is proven effective via simulations and experiments.

An analytical and explicit multi-field coupled nonlinear constitutive model for Terfenol-D giant magnetostrictive material

For a giant magnetostrictive rod under the action of multiple physical loads, such as an external magnetic field, temperature and axial pre-stress, this paper proposes a general one-dimensional nonlinear magneto-thermo-mechanical coupled constitutive model. This model is based on the Taylor expansion of the elastic Gibbs free energy of giant magnetostrictive material and thermodynamic relations from the perspective of macro continuum mechanics. Predictions made using this model are in good agreement with experimental data for magnetization and the magnetostrictive strain curve under the collective effect of pre-stress and temperature. Additionally, the model overcomes the drawback of the existing magneto-thermo-mechanical constitutive model that cannot accurately predict the magnetization and magnetostrictive strain curve for different temperatures and pre-stresses. Furthermore, the constitutive model does not contain an implicit function and is compact, and can thus be applied in both situations of tensile and compressive stress and to both positive and negative magnetostrictive materials, and it is thus appropriate for engineering applications. Comprehensive analysis shows that the model fully describes the nonlinear coupling properties of a magnetic field, magnetostrictive strain and elasticity of a magnetostrictive material subjected to stress, a magnetic field and heat.

Study on the dynamic characteristics of a high frequency brake based on giant magnetostrictive material

In order to meet the requirements of rapid and smooth braking, high-frequency braking using a giant magnetostrictive actuator is proposed, which can solve the problems in hydraulic braking, such as, it leaks easily, catches fire easily, is difficult to find failures, high cost on maintenance and repairing, etc. The main factors affecting the force of a high-frequency braking actuator are emphatically analyzed, the brakes dynamic model is established and a performance testing device for high frequency braking is constructed based on LabVIEW. The output force of the actuator increases with the excitation current of the driving coil increasing, and the increased multiple of the output force is greater than that of the excitation current; the range of the actuator force amplitude is 121.63 N ∼ 158.14 N, which changes little, while excitation frequency changes between 200 Hz ∼ 1000 Hz. In a minor range of pre-stress, the output force decreases with an increase in the axial pre-stress of the giant magnetostrictive rod, but is not obvious. It is known by finite element simulation analysis that high-frequency braking shortens the braking displacement and time effectively, which proves the feasibility and effectiveness of high frequency braking. Theoretical analysis and experimental results indicate that the output force of the actuator changes at the same frequency with excitation current; it is controllable and its mechanical properties meet the requirements of high frequency braking.

Revised reluctance model of the axial magnetic field intensity within giant magnetostrictive rod

A theoretical magnetic field intensity model within giant magnetostrictive material was presented. This model was established just like the reluctance model, while could describe the non-uniform distribution flexibly for its integral form. This model employed magnetic circuit theorem calculating the mean of the magnetic field, while used a normalized function describing the distributing character. The distributing function was determined by Biot–Savart law and relative permeability of the material. The model was validated with the help of the experimental device. At last, the fitting degree of the model with the tested results in predicting the performance of the actuator is researched.

Displacement model and driving voltage optimization for a giant magnetostrictive actuator used on a high-pressure common-rail injector

A novel giant magnetostrictive actuator driving the ball-valve of a high-pressure common-rail injector was designed in this paper. With the help of a special output rod, elongation of the giant magnetostrictive rod was converted to shortening of the actuator. So the actuator could suitable to a normally-closed injector. The traditional series equivalent circuit of the coil in the actuator was modified, and then the displacement model of the actuator was established and solved by a numerical method. The voltage, coil current and displacement of the actuator were acquired by a dedicated measuring system. Then the model was validated under the input voltages using sinusoid, AC square and DC square waveforms. A new driving voltage waveform suitable to the actuator was designed. And then the designed voltage was optimized for short responding time and slight fluctuation of the actuator displacement. The residual displacement caused by the hysteresis of giant magnetostrictive material was also considered.

A Design and Research on GMM Precision Flow Pump

A new type of the precision flow pump is developed with the giant magnetostrictive materials as the driving source. Experiment has been conducted to test the performance of the pump with designed key components. The pump as the preloading mechanism, adopting an elastomer instead of a spring, not only simplifies the structure, but also improves the performance of the pump. A design is also made to some key components such as the giant magnetostrictive rod and driving coil. The result of experiment shows that the pump flow resolution records 1 ml/min~400ml/min and the maximum output pressure 0.6 MPa, which means the performance of this kind of pump is superior to ordinary diaphragm pumps.

Experimental and theoretical study of the nonlinear response of agiant magnetostrictive rod

In this paper, a magnetomechanical coupling constitutive relation of the giant magnetostrictive material was investigated experimentally and theoretically. A grain-oriented magnetostrictive rod of iron and rare earth was tested under a combined magnetomechanical loading. Two types of experimental curves were obtained, i.e., the magnetostrictive curve of the extensional strain vs the magnetic field, and the curve of the magnetic polarization intensity vs the pre-stress. A new theoretical constitutive model, based on the density of domain switching, is developed. Comparison of the theoretical predictions with the experimental results indicates that this model can capture the main characteristics of the magnetoelastic coupling deformation of a giant magnetostrictive rod.

Development of active six-degrees-of-freedom microvibration control system using giant magnetostrictive actuators

An active six degrees-of-freedom microvibration control system using giant magnetostrictive actuators is developed in order to realize a microvibration-free space for precision instruments which hate vibration. A giant magnetostrictive actuator is suitable as a displacement actuator for active microvibration control, because it is both compact and durable and also its response against input is fast and reliable. The developed device consists of a table, six air springs, eight magnetostrictive actuators and six accelerometers on the table. Four actuators are set in the horizontal directions, and another four in the vertical direction. Since air springs and actuators as a unit of vertical support system are arranged in parallel, readjustment of the system is quite easy, even when the operating load on the table is changed. The dimensions of the table are 2000 mm length, 1400 mm width, 230 mm height and a weight of about 2 tons. The operating load on the table is 2 tons. A giant magnetostrictive rod is 6 mm in diameter and 50 mm long. The actuators operate within the stroke range of ±25 µm. A feedback control strategy using only six components of table acceleration on the table is adopted and the controller is designed by a model matching method. The obtained control performance of the system through two vibration control tests can be summarized as follows (1) Root-mean-square values of the table accelerations under micro-tremor are reduced to one-third to one-tenth of the floor accelerations, and kept less than 0.008 cm s-2. (2) Induced vibrations by impacts acting on the table disappear in less than 0.05 s.

Active Vibration Control of Frame Structures with Smart Structure Using Giant-Magnetostrictive Actuator.

A smart structure was tested for active vibration control of frame structures, in which bending moment of the columns was controlled by giant-magnetostrictive actuators integrated into the columns. The actuators were installed in two stages in the bottom part of the column. Excitation tests were carried out for a 3-story building model of a 3.4 m height and a 1, 600 kg total weight in which 8 actuators were installed in each column of the first story. The actuator consisted of a giant-magnetostrictive rod of a 40 mm length and a 20 mm diameter surrounded by a driving coil. Two control strategies including a model matching method and the H∞ control theory were examined for the smart structure. The tests showed that the smart structure could effectively reduce the responses of the building model, and the two control strategies had almost the same performance.

Active 6 DOF Microvibration Control System Using Giant Magnetostrictive Actuator.

Active microvibration control systems are becoming necessary in high-technology fields such as semiconductor manufacturing. In this study, an active 6 DOF microvibration control system using a giant magnetostrictive actuator was developed. The actuator consisted of a giant magnetostrictive rod of a 50mm length and a 6 mm diameter surrounded by a driving coil. A control law was adopted to provide almost the same performance as that of sky-hook systems by using only absolute acceleration, instead of achieving feedback of absolute displacement and velocity. Through vibration control experiments, it was shown that performance of the system was sufficient for implementation, including isolation performance against micro floor motion, damping performance against direct disturbance, and control system robustness.

Fundamental Study of Active Microvibration Control System Using Giant Magnetostrictive Actuator.

Active microvibration control systems are becoming necessary in high-technology fields, such as semiconductor manufacturing and microgravity experiments in space, to provide superior control performance to passive systems. In this study, an active system using a giant magnetostrictive actuator was tested using test apparatus designed for one-dimensional horizontal vibration control. The actuator consisted of a giant magnetostrictive rod with a 50 mm length and a 6 mm diameter surrounded by a driving coil. A control law was adopted, which could allow almost the same performance as sky-hook systems by feedback of only absolute acceleration of the isolation table. Vibration control experiments were carried out with satisfactory results in isolation performance against micro-floor motion, damping performance against direct disturbance and robustness of the control system.