Mode Magnetorheological Damper Research Articles

Performance evaluation of a novel squeeze mode magnetorheological fluid damper with pre-compression mechanism under small amplitude and medium-high frequency

Under small amplitude and medium-high frequency excitations, mechanical properties of squeeze mode magnetorheological (MR) damper change obviously which are different from general properties. Performance will be attenuated seriously which is known as the high frequency hardening effect. In this paper, mechanical performance of a novel squeeze mode MR damper with pre-compression mechanism under such excitations has been analyzed qualitatively and quantitatively. A novel squeeze mode MR damper with pre-compression mechanism is proposed to improve performance. Then, considering viscoelasticity, inertial effect and pre-compression, an optimized model has been proposed which can precisely describe the performance under such excitations. Comparing with experimental results, performances of squeeze mode MR damper under such excitations are quite different from general properties. The damping force decreases gradually without a sudden decrease at the maximum stroke and it shows stiffness characteristics obviously. What’s more, the maximum damping force is up to 1916 N with an increase of 321.6% at the current of 1 A and frequency of 10 Hz. The energy dissipation is increased by 342% with pre-compression of 1 MPa. The damping force and energy dissipation increase rapidly with increasing the pre-compression. Experimental results demonstrate that the high frequency hardening effect is effectively improved by pre-compression.

Study on the integrated structure/control design method of magnetorheological damper for improving vehicle posture

In order to achieve a good match between magnetorheological (MR) damper and vehicle Noise Vibration and Harshness (NVH) quality and improve vehicle posture while driving, an integrated design method of MR damper structure/control for vehicle vibration suppression was proposed considering the coupling effect between MR damper structure parameters and controller parameters. A controller was designed to control the damping force generated by the tapered channel MR damper. Furthermore, the damping force expression of the tapered flow mode MR damper was derived, and the damping force was introduced into the vehicle dynamics model. In order to improve the vehicle posture, an integrated structure/control platform combining response surface model, current controller and vehicle dynamics model was established. Based on integrated platform, the vehicle dynamics model and Fourier transform were adopted to extract the time-frequency characteristics of the design objective under different working conditions. In the optimization process, the damper structure was optimized by taking the time domain values as the constraints and the frequency domain values as the optimization goals. The results show that the proposed integrated design method of MR damper can obtain its global optimal structural parameters under different driving conditions. The acceleration root mean square (RMS) values and frequency domain values of vehicle were both reduced to varying degrees, achieving the purpose of improving the vehicle posture.

The effect of mesocarbon microbeads on magnetorheological fluid behavior

Magnetorheological (MR) fluids are composed of magnetizeable particles suspended in a carrier fluid and change apparent viscosity upon the application of a magnetic field. Previous studies have shown that passive particles, such as hollow glass spheres, can augment the yield stress of MR fluids, but this yield stress augmentation has limited endurance because the hollow glass microspheres are not sufficiently durable. This study evaluates mesocarbon microbeads (MCMBs) as an alternative passive particle with the potential for MR yield force augmentation but with greater durability. The yield properties of six MR fluid concentrations with varying carbonyl iron particle (CIP) and MCMB volume fractions were tested using a shear mode rheometer and flow mode MR damper. MCMBs did not augment yield stress in shear mode, but, in contrast, in flow mode, the yield force increased nonlinearly with MCMB volume fraction. Furthermore, this yield force-enhancing effect did not diminish over 100,000 cycles (or 5 km of piston travel). The theoretical non-dimensional plug thickness which arises from an approximate parallel plate analysis of a fluid element in flow mode is used illustrate to a potential mechanism for the yield force augmentation effect.

A new adaptive vibration control of magnetorheological damper system and its application to washing machine

Some undamped vibrations may cause undesirable behavior such as noise, overloads, excessive displacements, and early fatigue failures in the mechanical systems. Active vibration control is crucial for some of the mechanical systems such as washing machines. This article proposes a new vibration control strategy (VCS) for reduction of vibrations in washing machine. VCS utilizes adaptive nonlinear terminal sliding mode control (NTSMC) of double coil shear mode magnetorheological (MR) dampers and DC-DC buck converter. To achieve this goal, a control mechanism was designed that consists of two loops. The first loop implemented a force feedback control using proportional integral (PI) control and load cells. The second loop consists of adaptive NTSMC that was applied on buck converter to control current flow in MR dampers. The control law and finite convergence time to the equilibrium point were guaranteed for the current error using NTSMC. Moreover, an adaptive law was incorporated in NTSMC for the dynamic current control of MR dampers. The stability analysis of adaptive NTSMC was carried out using Lyapunov stability theory. An experimental setup was established for VCS that helps to study the performance of washing machine. A comparative analysis is presented for VCS with the passive dampers and other vibration control techniques that are reported in literature for washing machines.

Design and multi-objective optimization of magnetorheological damper considering vehicle riding comfort and operation stability

Mostly, magnetorheological (MR) dampers were optimized based on individual performance, without considering the influence of structure parameters change on vehicle performance. Therefore, a multi-objective optimization scheme of MR damper based on vehicle dynamics model was proposed. The finite element method was used to analyze magnetic flux density distribution in tapered damping channel under different structure parameters. Furthermore, the damping force expression of the tapered flow mode MR damper was derived, and the damping force was introduced into the vehicle dynamics model. In order to improve the ride comfort and operation stability of the vehicle, a collaborative optimization platform combining magnetic circuit finite element analysis and vehicle dynamics model was established. Based on this platform, the optimal design variables were determined by comfort and stability sensitivity analysis. The time domain optimization objective and frequency domain optimization objective are proposed simultaneously to overcome the lack of time domain optimization objective. The results show that compared with the time domain optimization and the initial design, the suspension dynamic deflection, tire dynamic load and vehicle body vertical acceleration are decreased after the time-frequency optimization. At the same time, in the frequency domain, the amplitude of vibration acceleration in each working condition is significantly reduced.

Simulation on hysteresis characteristic of squeeze mode magneto-rheological damper based on non-convex constitutive relation

Simulation on hysteresis characteristic of squeeze mode magneto-rheological damper based on non-convex constitutive relation

Numerical analysis of a monotube mixed mode magnetorheological damper by using a new rheological approach in CFD

In this study, the analytical Herschel-Bulkley fluid model of a monotube mixed mode MR damper was examined. The MR damper was modeled and simulated by using computational fluid dynamics (CFD) and magnetic finite elements analysis (FEA). The magnetic effects were modeled in a coupled manner with CFD. The actual rheological data was used in the CFD solver to find the cell-based viscosity by using a shear stress interpolation method. The MR damper was manufactured, and experiments were conducted to find the force-displacement and force-velocity correlations, and a good agreement was found between the numerical results and experimental data. The experimental results were also compared with analytical and numerical models under various current values. The CFD results are valuable in predicting the actual characteristics of the non-Newtonian flow inside an MR damper, and it can be used for various non-Newtonian fluid CFD models.

Shear Mode Damper Testing Using Flake Shape Based Magnetorheological Fluids

Use of anisotropic iron particles in the magnetorheological (MR) fluid having a high yield stress is a challenge as it increases the viscosity of the fluid in off-state. In this clause, a novel flake shaped iron powder based MR fluid with high yield stress is synthesized and used in shear mode MR damper (SMMD). MR damper design is optimized using fluid properties and Bingham model. Damping performance of newly synthesized MR fluid damper is at par with the available friction based damper used in front loaded washing machine. The unique feature of this design is minimal volume of the fluid (1.5 ml) required to achieve damping force of 50N. Effect of different volume percentage of particles in MR fluid is evaluated in terms of damping force. Effect of testing parameters like displacement and frequency of excitation on damping force was evaluated. Effect of settling of particle on damper performance is discussed in this work. It shows that the flakes shaped-based MR fluid show better stability against gravity. The smaller quantity of present flake shaped-based MR fluid will reduce the cost of shear mode damper.

Testing and Evaluation of Linear Shear Mode Magnetorheological (MR) Damper Based on Rheological Properties of MR Fluid

Abstract Magnetorheological (MR) fluid exhibits variable yield stress and viscosity with the magnetic field, which is why it is classified under smart materials. Because of its controllable properties, MR fluid has many applications. The most common application of MR fluid is MR fluid damper. According to the flow of MR fluid, three types of dampers are possible; flow mode, squeeze mode, and shear mode. In this article, rheological properties of MR fluid, which has a high Bingham number (ratio of MR force on-state to off-state), are synthesized and the MR properties are studied. Based on these properties, a linear shear mode MR damper is designed and evaluated for its performance. A unique model is adopted to evaluate the performance of MR damper. In this model, the dimensionless Mason number is applied to establish the relation between test data of damper and rheological properties of MR fluid. This is verified for two different volume fractions of magnetic particles in MR fluid.

Modelling and experimental investigation of a squeeze mode magnetorheological damper

In this paper, a novel mechanical model based on arc tangent function is established to accurately describe the hysteretic behavior of the squeeze mode Magnetorheological (MR) damper. An improved differential evolution (DE) algorithm, which can avoid

Seismic Mitigation of Building Frames using Magnetorheological Damper (TECHNICAL NOTE)

The present study focusses on the damping force control of shear mode magnetorheological (MR) damper for seismic mitigations. Therefore, the semi-active MR damper which can control the vibration is analyzed both experimentally and numerically. Carbonyl iron is used as the magnetic particle and Castrol Magnetec oil as carrier fluid throughout the study. MR damper is designed and fabricated, and its damping force was evaluated experimentally at 2.5 A- 10 V. Shear mode MR Damper is tested in universal testing machine using time history loading. The model was numerically analyzed using Newmark’s method for nonlinear system in MATLAB to control the three storey model building frame taken from the literature. The result indicates that 49.42% reduction in displacement at the second storey and 48.14% in the third storey, respectively. Maximum reduction was observed when damper was kept in the ground floor. The maximum force observed for the MR Damper is 0.777 kN.

Modeling and Control of a Shear-Valve Mode MR Damper for Semiactive Vehicle Suspension

Aiming at demonstrating the feasibility and capability of applying magnetorheological (MR) dampers to the vehicle vibration control, the hyperbolic tangent model is established to characterize the performance of a shear-valve mode MR damper that was developed for a vehicle suspension system in this study. An experimentally derived differential evolution (DE) algorithm is used to find the optimal parameters of the model. To demonstrate the effectiveness of the MR damper for semiactive suspension systems, a model was constructed of a quarter-car suspension system with the damper. A fuzzy control algorithm with a correction factor was adopted to control the output force of the damper and obtain better overall control of the performance of the suspension system. Simulation results indicate that the improved fuzzy control algorithm provides a better ride comfort than normal fuzzy control and passive control. Furthermore, the semiactive suspension system displayed effectively vibration suppression thanks to the MR damper combined with corresponding control algorithms.

Modeling and experimental verification of a squeeze mode magnetorheological damper using a novel hysteresis model

The squeeze mode of the magnetorheological damper can be used to stabilize precision instruments (balances, optical devices, etc.) to eliminate interference from external vibrational noise, due to the small displacement and large damping offered by the magnetorheological fluid. The squeeze-strengthen effect observed experimentally in the magnetorheological fluid with squeeze mode can lead to the strain stiffening phenomenon, which is similar to that of the magnetorheological elastomer. In this study, a novel model is developed to characterize the dynamics of the squeeze mode magnetorheological damper considering the strain stiffening hysteresis behavior. An experimentally derived differential evolution algorithm is used to identify the model parameters. Simulation results show that the proposed model can accurately describe the dynamics of the squeeze mode magnetorheological damper including the strain stiffening phenomenon. Furthermore, the identified results obtained by the proposed model appear to be better than those obtained by the hyperbolic model.

Design Optimization of Flow Mode Magnetorheological Damper

To control the vibrations with passive suspension system having limitation with constant damping force. By using smart material like magnetorheological fluid, it is possible to control the damping performance of suspension system using current variations in magnetic coil. Applications of this kind of damper are in front loaded washing machine and damper use in driver seat of heavy duty vehicles. Mainly flow mode MR damper is most commonly used damper for these two applications. This paper represents theoretical model and optimized design of flow mode MR damper. For any kind of MR damper design of magnetic coil is play very vital role. So for this paper mainly includes the design of coil and different parameters like number of coil distance between two coil current passing from the coil is consider for design and optimization using FEMM software. This work also includes the theoretical study of MR damper characteristics with force-displacement and force velocity plot with change in piston diameter and fluid gap.

Comparative Study on Wear Characteristics between Flow Mode and Shear Mode Magnetorheological Dampers

ABSTRACTThis comparative study experimentally examines the wear characteristics of magnetorheological (MR) dampers operated in flow mode and shear mode. First, electromagnetic coil structures are designed for two different MR dampers to maximize the field-dependent damping force. Two MR dampers are also designed to have the same volume of MR fluid for reasonable comparison. After identifying the field-dependent damping force at the initial state, the two dampers are operated up to 60,000 cycles using a reciprocating-type wear durability tester. The field-dependent damping forces are then evaluated before and after operation. The wear properties of the MR fluid are investigated using scanning electron microscope (SEM) images that show the changes in the MR fluid particles' size and shape. The surface roughness of the MR damper's piston areas are also measured. In addition, the effects of the permeability of the piston sleeve materials on the wear properties are investigated by selecting three different sleeve materials that have different permeability values: 0.2% carbon steel (S20C), 0.45% carbon steel (S45C), and tool die casting steel (STD-11). The surface roughness of each case is tested and the atomic spectrum is investigated after long operation using energy-dispersive X-ray spectroscopy (EDS) inside the piston. The experimental results obtained from this work indicate that the motion of the operating mode significantly affects the wear characteristics of the MR fluid itself as well as the magnetic effective areas of the MR dampers.

Design and control of a prosthetic leg for above-knee amputees operated in semi-active and active modes

This paper proposes a new prosthesis operated in two different modes; the semi-active and active modes. The semi-active mode is achieved from a flow mode magneto-rheological (MR) damper, while the active mode is obtained from an electronically commutated (EC) motor. The knee joint part of the above knee prosthesis is equipped with the MR damper and EC motor. The MR damper generates reaction force by controlling the field-dependent yield stress of the MR fluid, while the EC motor actively controls the knee joint angle during gait cycle. In this work, the MR damper is designed as a two-end type flow mode mechanism without air chamber for compact size. On other hand, in order to predict desired knee joint angle to be controlled by EC motor, a polynomial prediction function using a statistical method is used. A nonlinear proportional-derivative controller integrated with the computed torque method is then designed and applied to both MR damper and EC motor to control the knee joint angle. It is demonstrated that the desired knee joint angle is well achieved in different walking velocities on the ground ground.

Flow Mode Magnetorheological Dampers with an Eccentric Gap

This paper analyzes flow mode magnetorheological (MR) dampers with an eccentric annular gap (i.e., a nonuniform annular gap). To this end, an MR damper analysis for an eccentric annular gap is constructed based on approximating the eccentric annular gap using a rectangular duct with a variable gap, as well as a Bingham-plastic constitutive model of the MR fluid. Performance of flow mode MR dampers with an eccentric gap was assessed analytically using both field-dependent damping force and damping coefficient, which is the ratio of equivalent viscous field-on damping to field-off damping. In addition, damper capabilities of flow mode MR dampers with an eccentric gap were compared to a concentric gap (i.e., uniform annular gap).

Design of magnetorheological damper with a combination of shear and squeeze modes

Magnetorheological (MR) damper is a semi-active suspension device that uses MR fluid to produce controllable damper. The mechanical properties of the suspension can be controlled by adjusting the yield stress of MR fluid. This paper presents the design of a new concept for MR damper with a combination of shear and squeeze working modes. Finite Element Method Magnetics (FEMM) was utilized to simulate the magnetic field generated by electromagnetic coils in MR damper. The MR damper was designed and fabricated according to the simulation results. The experimental tests were performed under quasi-static loading in three different conditions; shear mode, squeeze mode and combination of both modes. The results showed that the mixed mode MR damper has produced a unique damping characteristic where in general, a higher damping force has obtained in mixed mode than single mode.

Parameters Consideration in Designing a Magnetorheological Damper

This paper presents a simulation study of electromagnetic circuit design for a mixed mode Magnetorheological (MR) damper. The magnetic field generated by electromagnetic circuit of the MR damper was simulated using Finite Element Method Magnetics (FEMM) software package. All aspects of geometry parameters were considered and adjusted efficiently in order to obtain the best MR damper performance. Eventually, six different parameters approach were proposed; the selection of materials, the polarity of coils, the diameter of piston, piston rod and core, the shear and squeeze gaps clearance, the piston pole length and the thickness of housing.

Unsteady analysis for oscillatory flow of magnetorheological fluid dampers based on Bingham plastic and Herschel–Bulkley models

It is known that a quasi-static analysis without considering fluid inertia is usually used for magnetorheological damper design. However, fluid inertia terms need to be incorporated into the governing Navier–Stokes equation in practical application for oscillatory or unsteady fluid flow. In this article, an unsteady flow of magnetorheological fluids within flow mode magnetorheological dampers was theoretically investigated under sinusoidal displacement excitation. Based on the governing Navier–Stokes equation, incorporating the boundary and initial conditions, central numerical velocity solutions of magnetorheological fluids within magnetorheological damping channel were developed and used to confirm the damping force using both Bingham plastic and Herschel–Bulkley models of magnetorheological fluids. To simplify the governing equation of Herschel–Bulkley flow, an approximation method replacing Herschel–Bulkley model velocity with Bingham plastic model velocity during calculating effective viscosity shear rate of Herschel–Bulkley model is proposed and used. For given magnetorheological fluid properties and flow mode magnetorheological damper geometry, under different yield stresses, sinusoidal excitation frequencies, and power-law exponent of Herschel–Bulkley model, the effects of magnetorheological fluid inertia terms on work and characteristic diagrams of magnetorheological dampers are discussed.