Damper Piston Research Articles

Development of a semi-active suspension using a compact magnetorheological damper with negative-stiffness components

Semi-active suspension with traditional magnetorheological (MR) dampers can attenuate vehicle’s vibration with less power consumption and high stability, nevertheless, it is not as effective as an active suspension. To further improve its vibration attenuation performance, this paper proposes a new MR damper with compact negative-stiffness components and analyses the effect of negative-stiffness characteristics on vibration attenuation performance. Its primary advantages include its high compactness which enables the suspension to be installed into the very limited space of real vehicles without any configuration change, and also its high effectiveness on reducing the vibrations as well as improving the vehicle stability. Upon the design of the new MR damper, a theoretical model and a mechanical model for the compact negative-stiffness component and the MR damper piston is established, respectively, to determine the suitable size of the negative-stiffness component and to optimize the parameters of the piston. Then the mechanical performance of the proposed new MRF damper is verified through an MTS machine. Finally, the new MR damper was mounted on a quarter-car system to evaluate its vibration attenuation performance under sky-hook algorithm by subjecting to different excitations. The experimental results demonstrated that the compact negative-stiffness MR damper has excellent vibration attenuation performance comparable to that of the active suspension.

Experimental Study on Magnetorheological Damper Prototype and Obtaining Its Equivalent Damping Coefficients

In this work, a magnetorheological (MR) damper prototype that provides controllable damping force was designed, manufactured and tested. The design and dimensions of the MR damper piston were determined according to the static magnetic analysis results made in ANSYS/Emag (Electromagnetics) software. The MR damper’s damping performance was tested in laboratory by utilizing a damper testing device. The tests were carried out under different currents applied to coil of the MR damper. According to the test results, the equivalent damping coefficients of the MR damper were calculated for different currents. The test results show that the highest damping force is 169.4 N with frequency of 3.18 Hz and applied current of 2 A. In this case, the equivalent damping coefficient is 302 Ns/m. The equivalent damping coefficient is 181 Ns/m when no current is supplied to the coil. The area of the dynamic force range also becomes larger with increasing the applied current. In addition, according to the quarter car model based simulation results in MATLAB/Simulink, it was seen that the semi-active suspension system using MR damper was more effective and successful in vibration mitigation.

Fluid dynamic vibration absorber for vehicle suspension system

The Fluid Dynamic Vibration Absorber (FDVA) is a dynamic vibration absorber where the inductance is gained by translated fluid mass and the capacitance by coil springs. Due to the hydraulic transmission, the FDVA is a lightweight component compared to other dynamic vibration absorbers. As shown in this paper, the FDVA reduces the wheel load fluctuation of a passenger car. After optimisation, the FDVA is integrated into a damper's piston rod. Experiments in a quarter-car test rig show the benefit of the integrated FDVA compared to a standard damper. Excited by a stochastic road profile, the measured benefit with FDVA is 3.5 % more comfort and 4.3 % less wheel load fluctuation.

Design optimization and experimental evaluation of a large capacity magnetorheological damper with annular and radial fluid gaps.

This paper presents an optimal design of a large-capacity Magnetorheological (MR) damper suitable for off-road vehicle applications. The damper includes an MR fluid bypass valve with both annular and radial gaps to generate a large damping force and dynamic range. An analytical model of the proposed damper is formulated based on the Bingham plastic model of MR fluids. To establish a relationship between the applied current and magnetic flux density in the MR fluid active regions, an analytical magnetic circuit is formulated and further compared with a magnetic finite element model. The MR valve geometrical parameters are subsequently optimized to maximize the damper dynamic range under specific volume and magnetic field constraints. The optimized MR valve can theoretically generate off-state and on-state damping forces of 1.1 and 7.41 kN, respectively at 12.5 mm/s damper piston velocity. The proposed damper has been also designed to allow a large piston stroke of 180 mm. The proof-of-concept of the optimally designed MR damper was subsequently fabricated and experimentally characterized to investigate its performance and validate the models. The results show that the proposed MR damper is able to provide large damping forces with a high dynamic range under different excitation conditions.

Shape optimization of magnetorheological damper piston based on parametric curve for damping force augmentation

Making full use of the magnetically controllable rheological properties of magnetorheological (MR) fluid, MR actuators have been applied in many engineering fields. To adapt to different application scenarios, parameters of MR actuators often need to be optimized. Previous MR actuator optimization was focused on finding optimal combinations of geometric dimensions and physical parameters that meet certain requirements. The parts with optimized dimensions were still in regular shape, which might not bring optimal damping performance. Therefore, in this paper, shape optimization of MR damper piston based on parametric curve is performed for the first time. First, the regional magnetic saturation problem in the previous prototype is stated. Then, the MR damper with normal piston is simulated as a reference. Later, Bezier curve, one of the typical parametric curves, is used to form the piston with optimized parameters, and the MR damper with optimized piston is also simulated. Finally, prototypes of the MR dampers with normal and optimized pistons are fabricated and tested. Compared with the MR damper with normal piston, the one with optimized piston has larger field dependent force and total damping force under relatively large current, with about 52% and 24% maximum increasing percentage, respectively. The controllable force range of the MR damper with optimized piston is also larger than that with normal piston.

Ідентифікація несправностей опор амортизаційних стійок легкових автомобілів

The goal of current research is the systematization of information from existent constructions of upper supports, features of support elements load depending on their constructions, analysis aspects, which influence supports attrition and their probable defects, and also giving recommendations for diagnostics. The informational analysis made due to existent upper supports constructions, features of their action in exploitation conditions, considered factors which influence on supports attrition, and their probable defects. Considered supporting bearer and rubber damping elements of damper strut supports fail indications. Fail of rubber damping elements characterized by the range of attributes. Due to car exploitation take place support detail attrition, rubber damping elements of supports waste their elasticity, crack and delaminate from the metal details, rubber damping supports stretch, which leads to support`s contact with upper springs cap and attends with singular thumps. Due to bearing attrition level of rattling and decreasing driving comfort are much higher than due to rubber element attrition. Features of increased bearing attrition are next: rattling by rudder turning occurrence (can also take place on the steering wheel), deterioration of car control. Bearing attrition appears in terms of squeaks and jerks in the process of steering wheel turning in the cars without a power steering. Due to attrition bearing starts to play, thump, and damper piston rod deviates from own axle. During car motion on the small roughs with depleted bearings also perceived rattling from the side of suspender, which sometimes can be difficult to identify, because it is analogous to rattling caused by attrition of other details of suspender or steerage. Offered to realize damper strut supports diagnostics by the way of support` action in a car moving conditions on the pocky surface simulation, to solve this task recommended to use vibration stand for suspender diagnostics. Offered to use the identification of hits and vibrations in foreworn supports via vibration acceleration sensor with later processing.

Analyzing quarter car model with Magneto-Rheological (MR) damper using equivalent damping and Magic formula models

Mathematical modelling of Magneto-Rheological (MR) damper has been an intriguing field of research ever since the invention of the device itself. An accurate model of MR damper results in development of an efficient controller for a semi-active system with MR damper. Hence, a number of models have been put forward to accurately predict the MR damper behavior. One of these models is Magic formula model. Based on the famous Magic formula used in tire force calculation, this model can be used for representing the peak damper force vs damper piston velocity amplitude graph. This model was later modified to capture the force displacement diagram of MR damper. The former model is denoted as Magic Formula Model-1 (MFM-1) and the latter one is denoted as Magic Formula Model-2 (MFM-2) here onwards. In the current study a commercial MR damper has been tested for various piston velocities and currents. The equivalent damping coefficient is then calculated for the tested conditions. The equivalent damping coefficients are used for analyzing a quarter car model. Two quarter car models with MR damper are simulated, one uses MFM-1 for MR damper and the other uses MFM-2. All the quarter car models are subjected to single pulse input and the sprung mass response is measured in terms of displacement. The RMS error between the response of quarter car model with equivalent damping and quarter car models with MR damper is used to determine the performance of each mathematical model. The study revealed that MFM-1 represents the MR damper behavior more accurate than that of MFM-2.

Semi-Active Scissors-Seat Suspension With Magneto-Rheological Damper

A cab seat suspension with a magneto-rheological (MR) fluid damper is introduced in this paper. A unified-format model for the MR damper is proposed to describe the dynamic characteristics of the MR damper. Also, a simple force-inverse model and a viscous damping tracking model are used for the coil current solution. A digital integrator and an extended Kalman filter are respectively adopted to obtain the vibration velocity of the chair frame and the relative motion velocity of the MR damper piston. A new skyhook control base with viscous damping tracking is applied to the semi-active seat suspension. In the simulation, compared with passive seat suspension under different displacement excitation (2, 4, 6, 8 Hz-sine, and random), the acceleration root mean square of the seat suspension with the MR damper is reduced by 52.2%, 32.2%, 41.3%, 50.8%, and 34.6%, respectively. In the experiment, the acceleration root mean square is reduced by 11.2%, 41.2%, 45.8%, and 31.5%, respectively under different displacement excitation (2, 4, 6, and 8 Hz-sine).

Performance Analysis of a Novel Magnetorheological Damper with Displacement Self-Sensing and Energy Harvesting Capability

External sensors are vulnerable to the external magnetic field, temperature, noise, and other factors in the semi-active control system based on magnetorheological (MR) damper, which not only reduces the reliability and stability but also increases the complexity, installation space, and system cost. Meanwhile, mechanical energy is generally dissipated as heat due to the friction between the cylinder and damper piston of the MR damper. To further broaden the applications of MR damper, it is essential to maintain excellent functions when the power supply is cut off in various emergencies. Based on this, a novel MR damper with displacement self-sensing and energy harvesting capability is proposed to solve the problems such as large structural size, high system cost, and vibration energy dissipation. Firstly, the structures of the MR damping, displacement self-sensing, and vibration energy harvesting are designed and integrated into the proposed MR damper. Then, the distribution of the magnetic flux density, displacement self-sensing voltage, and energy harvesting efficiency with a single induction coil and double induction coil is obtained using the finite element method. The experimental test system is set up and the performance of MR damping, displacement self-sensing voltage, and energy harvesting efficiency is experimentally tested. The experimental results show that the damping force reaches 513 N at the applied current of 0.25 A. At the same time, the amplitude of self-sensing voltage increases linearly with the increase of the amplitude of sinusoidal displacement excitation, and the displacement sensitivity comes up to 54.37 mV/mm. Moreover, the self-sensing voltage of the vibration energy harvesting component with a double induction coil is 2.512 V, and the energy harvesting efficiency is about twice than that with a single induction coil. It is found that the proposed MR damper, with a relatively compact structure and lower cost compared with traditional MR damper, not only promisingly achieves excellent dynamic damping performance but also simultaneously possesses displacement self-sensing ability and energy harvesting capability.

Design optimization of magnetorheological damper geometry using response surface method for achieving maximum yield stress

Field controllable magnetorheological (MR) damper has gained prominence as a suitable vibration control device for a wide variety of applications as they offer the combined advantages of high-performance metrics of a fully active vibration control system with the cost metrics of a passive vibration control system. The functional quantity that influences the damping performance of a magnetorheological damper is the yield stress of the magnetorheological fluid across the fluid flow gap when the magnetic field is applied. To achieve maximum damping output from the magnetorheological damper, the geometry of the damper piston needs to be optimized. The main geometrical design parameters of the damper piston are the pole width, magnetorheological fluid flow gap, distance between piston rod and coil and the outer pole thickness. The optimization of the damper geometry is carried over with magnetic field strength and yield stress as response variables in two different iterations. A quadratic polynomial function is considered for both the response variables. The yield stress response variable is found to exhibit a more accurate following through the regression equation and it is selected as the response variable of choice. The individual effect of each of the design variable and the interaction effect of the design variables over the yield stress response variable is studied in this research paper. The optimal values of the piston geometry could be used to fabricate a magnetorheological damper prototype in future study.

Transient Magnetic Model of Magnetorheological Damper and Its Experimental Verification

The present paper deals with the transient magnetic model of the magnetorheological (MR) damper and its experimental verification. The response time of MR damper affects the quality of semi-active control of this damper. The lower the response time, the higher the system efficiency. The most important part of the response time of the MR damper is the response time of magnetic field of the MR damper which can be determined by transient magnetic model. The transient magnetic model was created by the software Ansys Electromagnetics 17.1 as 2D axisymmetric and verified by measurement of magnetic field in the gap of MR damper piston. The maximum difference between the model and the experiment was 28 %. The response time depends on the electric current in the coil of MR damper. The transient magnetic model was used for determination of influence of MR fluid type, material of cover and material of magnetic circuit on the response time of magnetic field of MR damper. The type of MR fluid has a significant influence on the response time. The lower the mass concentration of ferromagnetic particles, the lower the response time of magnetic field. A material selection of magnetic circuit is always a trade-off between the response time and the maximum magnetic flux density (dynamic force range) in the gap of the MR damper. According to the verified transient magnetic model, it is possible to find a suitable material of magnetic circuit for specific application (response time).

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.

Semi-active vibration control using experimental model of magnetorheological damper with adaptive F-PID controller

The aim of this research is to develop a new method to use magnetorheological (MR) damper for vibration control. It is a new way to achieve the MR damper response without the need to have detailed constant parameters estimations. The methodology adopted in designing the control structure in this work is based on the experimental results. In order to investigate and understand the behaviour of an MR damper, an experiment is first conducted. Force-displacement and force-velocity responses with varying current have been established to model the MR damper. The force for upward and downward motions of the damper piston is found to be increasing with current and velocity. In cyclic motion, which is the combination of upward and downward motions of the piston, the force with hysteresis behaviour is seen to be increasing with current. In addition, the energy dissipated is also found to be linear with current. A proportional-integral-derivative (PID) controller, based on the established characteristics for a quarter car suspension model, has been adapted in this study. A fuzzy rule based PID controller (F-PID) is opted to achieve better response for a varying frequency input. The outcome of this study can be used in the modelling of MR damper and applied to control engineering. Moreover, the identified behaviour can help in further development of the MR damper technology.

Nonlinear modeling of adaptive magnetorheological landing gear dampers under impact conditions

Adaptive landing gear dampers that can continuously adjust their stroking load in response to various operating conditions have been investigated for improving the landing performance of a lightweight helicopter. In prior work, adaptive magnetorheological (MR) landing gear dampers that maintained a constant peak stroking force of 4000 lbf across sink rates ranging from 6 to 12 ft s−1 were designed, fabricated and successfully tested. In this follow-on effort, it is desired to expand the high end of the sink rate range to hold the peak stroking load constant for sink rates ranging from 6 to 26 ft s−1, thus extending the high end of the speed range from 12 (in the first study) to 26 ft s−1. To achieve this increase, a spring-based relief valve MR landing gear damper was developed. In order to better understand the MR landing gear damper behavior, a modified nonlinear Bingham Plastic model was formulated, and it incorporates Darcy friction, viscous forces across the MR and relief valves to better account for the damper force behavior at higher speeds. In addition, gas pressure inside the MR damper piston is considered so the total damper force includes a gas force. The MR landing gear damper performance is characterized using drop tests, and the experiments are used to validate model predictions data at low and high nominal impact speeds up to 26 ft s−1 (shaft velocity of 9.6 ft s−1).

SIDE FORCE ANALYSIS OF SUSPENSION STRUT UNDER VARIOUS LOAD CASES

This paper presents the side forces extraction of a Macpherson suspension strut under extreme load cases using multibody dynamics model. Inevitable side forces subjected to the Macpherson suspension system during vehicle driving cause the damper rod and top mounting failure. Bending moment generated could increase the friction of damper piston and inner tube and simultaneously decrease the ride comfort of the vehicle, or in a more severe condition, failure occurs. In this study, the side forces magnitude subjected to the Macpherson strut under various severe load events were obtained through a quasi-static multibody dynamics half vehicle model simulation. Outcomes of the multibody simulation that showing the forces exerted on the suspension Macpherson strut were derived into three axes which were vertical, lateral and longitudinal. The lateral and longitudinal side forces on the strut were highest during the pothole striking event which achieved 11052 N. The extracted force provided useful information for suspension linkages design and damper friction analysis to prevent failure.

Numerical study of magnetic circuit response in magneto-rheological damper

Purpose – The purpose of this paper is to evaluate the performance of the semi-active fluid damper. It is recognized that the performance of such a damper depends upon the magnetic and hydraulic circuit design. These dampers are generally used to control the vibrations in various applications in machine tools and robots. The present paper deals with the design of magneto-rheological (MR) damper. A finite element model is built to analyze and understand the performance of a 2D axi-symmetric MR damper. Various configurations of damper with modified piston ends are investigated. The input current to the coil and the piston velocity are varied to evaluate the resulting change in magnetic flux density (B), magnetic field (H), field dependent yield stress and magnetic force vectors. The simulation results of the various configurations of damper show that higher magnetic force is associated with plain piston ends. The performance of filleted piston ends is superior to that of other configurations for the same magnitude of coil current and piston velocity. Design/methodology/approach – The damper design is done based on the fact that mechanical energy required for yielding of MR fluid increases with increase in applied magnetic field intensity. In the presence of magnetic field, the MR fluid follows Bingham’s plastic flow model, given by the equation τ = η γ•+τ y (H) τ > τ y . The above equation is used to design a device which works on the basis of MR fluid. The total pressure drop in the damper is evaluated by summing the viscous component and yield stress component which is approximated as ΔP = 12ηQL/g3W + CτyL/g, where the value of the parameter, C ranges from a minimum of 2 (for ΔPτ ΔPη less than approximately 1) to a maximum of 3 (for ΔPτ/ΔPη greater than approximately 100). To calculate the change in pressure on either side of the piston within the cylinder, yield stress is required which is obtained from the graph of yield stress vs magnetic field intensity provided by Lord Corporation for MR fluid −132 DG. Findings – In this work, three different finite element models of MR damper piston are analyzed. The regression equations, contour plots and surface plots are obtained for different parameters. This study can be used as a reference for selecting the parameters for meeting different requirements. It is observed from the simulation of these models that the plain ends model gave optimum magnetic force and 2D flux lines with respect to damper input current. This is due to the fact that the plain ends model has more area when compared with that of other models. It is also observed that filleted ends model gave optimum magnetic flux density and yield stress. As there is reduced pole length in the filleted ends model, the MR fluid occupies vacant area, and hence results in increased flux density and yield shear stress. The filleted ends assist the formation of dense magnetic flux lines thereby increasing the flux density and yield stress. This implies that higher load can be carried by the filleted ends damper even with a smaller size. Originality/value – This work is carried out to manufacture different capacities of the dampers. This can be applied as vibration controls.

Some Dynamic Behaviour Aspects Related to a Vehicle Suspension

Some of the aspects of the vehicle suspension limiting performances from stress and vibrations point of view have been explored in this study. The vehicle is modeled as two DOF system and the suspension is considered a passive one. 3D CATIA model was built for both the spring and spring-damper ensemble, neglecting the tire influence. This can reasonably covers the studies of geometries and forces (bending or tensile stress), masses and stiffnesses (meaning vibration profiles). The theoretical analysis on the vibration behaviour of the spring-damper ensemble, regarded as the vehicle suspension, suggests a convenient operation regime at low frequencies below 15 Hz, if the damper piston displacement is limited.

Static and Dynamic Experiment Evaluations of a Displacement Differential Self-Induced Magnetorheological Damper

This paper presents the development of a novel magnetorheological damper (MRD) which has a self-induced ability. In this study, a linear variable differential sensor (LVDS) based on the electromagnetic induction mechanism was integrated with a conventional MRD. The structure of the displacement differential self-induced magnetorheological damper (DDSMRD) was developed, and the theory of displacement differential self-induced performance was deduced. The static experiments of the DDSMRD under different displacement positions were carried out by applying sine excitation signals to the excitation coils, and the experimental results show that the self-induced voltage is proportional to the damper piston displacement. Meanwhile, the dynamic experiments were also carried out using the fatigue test machine to investigate the change of the self-induced voltage under the typical direct current inputs and the different piston rod displacements; the experimental results also show that the self-induced voltage is proportional to the damper piston displacements. Additionally, the dynamic mechanical performance of the DDSMRD was evaluated. The theory deduction and the experimental results indicate that the proposed DDSMRD has the ability of the integrated displacement sensor in addition to the output controllable damping force.

Optimal design of Magneto-Rheological damper comparing different configurations by finite element analysis

Magnetorheological (MR) damper is one of the most advanced applications of semi active damper in controlling vibration. Due to its continuous controllability in both on and off state its practice is increasing day by day in the vehicle suspension system. MR damper’s damping force can be controlled by changing the viscosity of its internal magnetorheological fluids (MRF). But still there are some problems with this damper such as MR fluid’s sedimentation, optimal design configuration considering all components of the damper. In this paper both 2-D Axisymmetric and 3-D model of MR Damper is built and finite element analysis is done for design optimization. Different configurations of MR damper piston, MR fluid gap, air gap and Dampers housing are simulated for comparing the Dampers performance variation. From the analytical results it is observed that among different configurations single coil MR damper with linear plastic air gap, top and bottom chamfered piston end and medium MR fluid gap shows better performance than other configurations by maintaining the same input current and piston velocity. Further an experimental analysis is performed by using RD-8041-1 MR Damper. These results are compared with the optimized MR Damper’s simulation results, which are clearly validating the simulated results.

Energy-harvesting linear MR damper: prototyping and testing

The present study is concerned with an energy-harvesting linear MR (EH-LMR) damper which is able to recover energy from external excitations using an electromagnetic energy extractor, and to adjust itself to excitations by varying the damping characteristics. The device has three main components: an MR part having a damper piston assembly movable in relation to the damper cylinder under an external excitation, a power generator to produce electrical power according to the relative movement between the damper piston and the cylinder assembly, and a conditioning electronics unit to interface directly with the generator and the MR damper. The EH-LMR damper integrates energy harvesting, dynamic sensor and MR damping technologies in a single device. The objective of the study is to get a better insight into the structure of EH-LMR damper components, to investigate the performance of each component and a device as a whole, and to compare results of experimental study against numerical data obtained in simulations conducted at the design stage. The research work demonstrates that the proposed EH-LMR damper provides a smart and compact solution with the potential of application to vibration isolation. The advantage of the device is its adaptability to external excitations and the fact that it does not need any extra power supply unit or sensor on account of its self-powered and self-sensing capabilities.