Fluid Damper Research Articles

Steady-State and Bifurcation Analysis of Nonlinear Jumps in a Non-ideal Rotor System Using Magnetorheological Fluid Dampers

Steady-State and Bifurcation Analysis of Nonlinear Jumps in a Non-ideal Rotor System Using Magnetorheological Fluid Dampers

Preliminary Design of Seismic Isolation Systems Using Artificial Neural Networks

This works attempts to implement artificial neural networks (ANN) for modeling Seismic-Isolation (SI) systems consisting of Natural Rubber Bearings and Viscous Fluid Dampers subject to Near-Field (NF) earthquake ground motion. Fourteen NF earthquake records representing two seismic hazard levels are used. The commercial analysis program SAP2000 was used to perform the Time-History Analysis (THA) of the MDOF system (stick model representing a realistic five-story base-isolated building) subject to all 14 records. Different combinations of damping coefficients (c) and damping exponents (α) are investigated under the 14 earthquake records to develop the database of feasible combinations for the SI system. The total number of considered THA combinations is 350 and were used for training and testing the neural network. Mathematical models for the key response parameters are established via ANN. The input patterns used in the network included the damping coefficients (c), damping exponents (α), ground excitation (peak ground acceleration, PGA and Arias Intensity, Ia). The network was programmed to process this information and produce the key response parameters that represent the behavior of SI system such as the Total Maximum Displacement (DTM), the Peak Damper Force (PDF) and the Top Story Acceleration Ratio (TSAR) of the isolated structure compared to the fixed-base structure. The ANN models produced acceptable results with significantly less computation. The results of this study show that ANN models can be a powerful tool to be included in the design process of Seismic-Isolation (SI) systems, especially at the preliminary stages.

Fluid–structure interaction and dynamic stability of shock absorber check valves

Shock absorbers, also known as dampers, are a crucial part of most vehicles produced today and ensure both safety and comfort of passengers by absorbing displacement changes through fluid–structure interaction (FSI) between the contained mineral oil and elastic metal valves. In this study, the two most common types of shock absorber valves, namely the spring valve and the shim valve, are investigated in both compression and rebound operation of a typical motorcycle suspension system. Depending on the flow direction, different properties of the valve system are desired, which are demonstrated for realistic boundary conditions. By using both high-order FSI simulations as well as a low-order analytical model, stability and nonlinear dynamics of the valve are computed within the system’s parameter space and the opening and closing characteristics are obtained for typical volumetric flow rates. Additionally, the adhesion force due to viscous stiction between valve plate and seat area by the damper fluid is taken into account, causing delay of opening especially at high excitation velocities and frequencies. It is demonstrated that significant pressure losses of more than 95% during compression take place in the small gap region between shim valve and piston due to frictional effects. Additionally, the check valve response time during transition from rebound to compression is reduced from 3.7ms down to 0.4ms by optimizing spring properties, which limit hysteresis effects. Linear stability analysis using the Routh–Hurwitz criterion shows the onset of instabilities at a flow rate of 95.9Lmin−1 for the baseline setup, with parameters such as damping and valve opening section negatively affecting stability at lower values. Finally, frequencies of valve vibrations during rebound are calculated and their dependence on the most important parameters of the valve, such as pretension and stiffness, are examined.

Comparison of discrete-time sliding mode control algorithms for seismic control of buildings with magnetorheological fluid dampers

Semi-active control implementations for structures are gaining considerable attention in civil engineering. This paper presents a method for the design and implementation of the discrete-time sliding mode controller with a hybrid control strategy, based on Gao’s reaching law and the variable rate reaching law, for practical applications in civil structures by using magnetorheological (MR) dampers. The structure is modeled as a five-degree-of-freedom lumped mass system, controlled by an MR damper placed in between the ground and the first floor. The MR damper is experimentally tested and its behavior is represented by using modified Bouc–Wen model and artificial neural network (ANN) as forward and inverse models, respectively. The five-story building is simulated under the seismic excitation of El Centro earthquake along with the historical earthquake records, Northridge and Kobe. It is demonstrated that the hybrid control strategy yields better results regarding the energy consumption of the controller and time-averaged structural responses by eliminating the chattering, compared to Gao’s controller.

Real-time adaptive leg-stiffness for roll compensation via magnetorheological control in a legged robot

Over the recent few decades, the evolving research-field of legged robotics has seen various mechanical and control-based developments. Inspired by biological species, a significant adaptation in modern mechanical leg designs has been the implementation of adjustable stiffness, shifting from what were previously simple linkages to more-complex variable stiffness actuators. Physiological studies previously demonstrated leg-stiffness modulation was not only a common trait in multiple biological locomotors, but also played a key role in disturbance recovery for humans. Guided by this, recent robotics research has shown that this can also be applied to legged robots to achieve similar locomotion adaptations, albeit often limited by the tuning time of leg stiffness in such circumstances. This study proposes real-time adaptive stiffness robot legs which are governed by fast-response magnetorheological fluid dampers, enabling stiffness adjustment upon a single step. Through experimental characterisation and model validation, these legs are shown to achieve a maximum stiffness shift of 114%. Enabled by real-time control during locomotion, improved performance and roll-angle stability is experimentally demonstrated for a bipedal robot test platform. Such improvement to locomotion is found through typical legged locomotion scenarios, with the platform encountering: obstacles, valleys, and coronal gradients in a comprehensive series of experiments.

Vibration control of primary and subharmonic simultaneous resonance of nonlinear system with fractional-order Bingham model

The passive vibration control of primary and subharmonic simultaneous resonance for the Duffing-type nonlinear system under the base excitation and external excitation by using magnetorheological (MR) fluid damper is studied, where the fractional-order derivative Bingham model of MR fluid damper is considered. The approximate analytical solution of the system is obtained by using the incremental averaging method. On the basis of obtaining the primary resonance of the system under base excitation by the averaging method, the subharmonic resonance solution of the system is obtained by taking the subharmonic resonance of the system under base excitation and external excitation as an increment, so as to obtain the approximate analytical solution of the simultaneous resonance of primary and subharmonic resonance. And the amplitude–frequency equation and phase–frequency equation of the steady-state solutions for the primary and subharmonic resonance of the system are derived respectively. According to the approximate analytical solutions, the stability conditions of the steady-state solution of the primary resonance and subharmonic simultaneous resonance are obtained by Lyapunov method. Compared with the numerical solution, the correctness and accuracy of the analytical solution of the primary resonance and subharmonic simultaneous resonance are demonstrated. The influence of system parameters on the resonant response of the system is analyzed in detail, with emphasis on the resonance bifurcation behavior of the system. The analysis results show that the damping passive vibration reduction control has obvious vibration suppression effect on the primary and subharmonic simultaneous resonance of the Duffing-type nonlinear system. Under certain conditions, there are 9 branches in the steady-state amplitude–frequency response of the primary and subharmonic simultaneous resonance of the Duffing-type system, of which 5 branches are stable solutions.

Identification of limiting damping mechanisms in a high quality factor hybrid resonator of space application gyroscope

• Studied hybrid gyroscope resonator damping mechanisms with imperfection sensitivity. • Realized thin film coated high precision resonator with few millions quality factor. • Limiting damping mechanisms are identified at each stage from design to realization. The performance of Hemispherical Resonator Gyroscopes (HRG) is decided by the mechanical resonator’s Quality factor ( Q factor). The Q factor is a measure of energy dissipation. A Q factor of few millions is needed to realize fine resolution millimeter size of the HRG for future interplanetary satellite missions. The objective is to carry out a detailed study of thermoelastic damping (TED), anchor loss, surface loss, material internal friction and fluid damping. A hybrid resonator is designed with very low TED. One of the major contributions of the present work is the study of the effect of thin film coating and different coating configurations on TED. Extensive simulations have been carried out on the effect of different fabrication deviations on anchor loss. A unique sensitivity study of mode interactions and mass unbalance pattern on frequency split and anchor loss mismatch is also done. Based on this, dimensional and geometric tolerances are derived for precision fabrication and the precision hybrid configuration resonator is realized. Surface loss and material internal friction are estimated. Also, surface characterisation has been done using nanoindentation techniques. Q factor of few millions is obtained in a fabricated precision resonator with thin film coating. Based on the estimation of different damping mechanisms and measurements, the limiting mechanisms are identified at each stage from the design to the realization. The Q factor of an uncoated resonator is limited by the surface loss while that of a coated resonator is limited by the coating induced additional TED, the coating material internal friction and the surface loss.

MAGNETO-RHEOLOGICAL (MR) DAMPER – PARAMETRIC MODELLING AND EXPERIMENTAL VALIDATION FOR LORD RD 8040-1

Magneto-rheological (MR) fluid technology has significantly developed during the past decades. The application of MR fluids has proliferated in various engineering fields with the development of MR fluid-based devices, especially MR fluid dampers. MR dampers are semi-active devices used for vibration reduction in many engineering applications. The MR dampers could offer an outstanding capability in semi-active vibration control due to excellent dynamical features such as fast response, low power consumption, and simple interfaces between electronic input and mechanical output. Modelling of MR damper is crucial in describing MR damper’s behaviour. It is critical to comprehend the dynamic behaviour of these devices, as nonlinear hysteresis is a rather complex phenomenon. The Modified Bouc-Wen model represents the MR damper mathematically since this model is capable of performing as precisely as the non-parametric model. The Modified Bouc-Wen model parameters are damper dependent and must be defined for further simulation studies before utilising the damper. Validation of MR damper experimentally is one of the tasks required to confirm the parametric model performance. The specified parameters are believed to be worthwhile for this MR damper’s use in further studies of real-time semi-active (SA) suspension systems. The small values of percentage difference for force (0.5-3.5%) indicate that the parameters implemented in the Modified Bouc-Wen model accurately portray the characteristics and behaviour of the MR damper.

Skyhook Control Law Extension for Suspension with Nonlinear Spring Characteristics

This work aimed to improve the vehicle body stability and the ride comfort of the tracked military vehicle crew. For this purpose, magnetorheological fluid dampers were used. This process has made the theoretical model of the tracked platform a semi-active suspension system. This modification allows for the application of different control laws to these systems. The usage of the continuous skyhook control law assumes the influence of three fictitious viscous dampers. Their force in this conceptual model is replicated by the magnetorheological dampers of the suspension in the real system. However, the continuous skyhook control law does not take into consideration the nonlinear stiffness characteristics. In this paper, the continuous skyhook control law has been appropriately modified. The modification takes into consideration the nonlinearity of the stiffness characteristics. Applying the modified continuous skyhook control law improves the stability of the vehicle body and the vehicle crew’s ride comfort. All these goals had to be introduced due to the modernization of the tracked military vehicle suspension by replacing the torsion bars with spiral spring packages with nonlinear characteristics.

A Semi-Active Control Technique through MR Fluid Dampers for Seismic Protection of Single-Story RC Precast Buildings.

The work proposes an innovative solution for the reduction of seismic effects on precast reinforced concrete (RC) structures. It is a semi-active control system based on the use of magnetorheological dampers. The special base restraint is remotely and automatically controlled according to a control algorithm, which modifies the dissipative capability of the structure as a function of an instantaneous dynamic response. The aim is that of reducing the base bending moment demand without a significant increase in the top displacement response. A procedure for the optimal calibration of the parameters involved in the control logic is also proposed. Non-linear modelling of a case-study structure has been performed in the OpenSees environment, also involving the specific detailing of a novel variable base restraint. Non-linear time history analyses against natural earthquakes allowed testing of the optimization procedure for the control algorithm parameters, finally the capability of the proposed technology to mitigate seismic risk of new or existing one-story precast RC structures is highlighted.

Effect of temperature on the mechanics of magnetorheological fluid damper

ABSTRACT As a kind of smart damping controllable device, magnetorheological (MR) fluid damper is a hot research topic in the field of vibration control. In this paper, the mechanical properties of MR damper under different temperatures were investigated. A set of test systems, including force sensors, data acquisition platform, stepper motor and K-type temperature sensor was built to test the damping force of MR damper. LabVIEW software was used to compile a data acquisition platform and collect the voltage signals of temperature and pressure sensors, and the data were analyzed by Matlab software. The damping force of the MR damper under different temperatures was obtained. The result shows that, at the range of 20 ~ 40°C, the temperature has a great influence on the MR damper, and the damping force decreases with the increasing of temperature.

Development and Implementation of Energy-Efficient Magnetorheological Fluid Bypass Damper for Prosthetics Limbs Using a Fuzzy-Logic Controller

Walking behaviour in amputees with lower-limb loss is absent from shock-absorbing properties. A damper can be used to reduce the impact of ground reaction force (GRF) during heel strikes. Magnetorheological fluid (MRF) damper is deemed the best option for this application as it includes the advantages of both passive and active dampers. An enhanced MRF damper is essential in supplying the appropriate current and damping force levels. Therefore, an energy-efficient design is required to prolong the battery life used by MRF dampers in prosthetic limbs. This paper investigates two fluids of different properties and magnetic particle volume content. A bypass damper was used to observe the response of both fluids. The findings highlighted that an MRF with a higher percentage of solid weight could produce a more significant damping force with a lesser amount of applied current. This work presents a simulation study on implementing the energy-efficient MRF damper utilizing a Fuzzy-PID controller in a prosthetic limb.

Optimal Evaluation of the Rheological Parameters for STF Dampers in Semi‐Rigid Joints of Steel Structures Using Response Surface Method

This work deals with the multiobjective optimization of rheolohical parameters on a novel designed flexible joints using shear thickening fluid dampers (STFD) on steel structures. The proposed damper consists of the shear thickening fluid (STF) with the combination of nano‐silica and PEG (400) sonicated to achieve colloidal dispersion of nanoparticles. Series of cyclic loading were imposed on the frames equipped with STF dampers to assess their impacts on T‐steel frames. The stiffener end plate is bolted over the corner of the joints that are subjected to bending moment. The multi‐objective optimization using the response surface method of the rheological parameters for STF dampers was studied in order to reduce the dynamic forces and moments produced in a semi‐rigid joint of the steel structures. Results from the analysis were used to obtain correlations between the response variables and the input factors (effective stiffness of 449.89 N/mm, complex viscosity of 98.69 Pa.s, and damping constant of 446.99 N.s/mm) for the proposed STF damped semi‐rigid joints.

Online DE Optimization for Fuzzy-PID Controller of Semi-Active Suspension System Featuring MR Damper

In pursue of a comfortable vehicle driving in different road profiles, intelligent methods used to improve the suspension system of the vehicle. Semi-active suspension system outperformed other suspension systems because it contains an intelligent actuator that can give the appropriate force to dissipate unwanted vibration using intelligent and real-time controllers. Here in this paper MR fluid damper with Fuzzy-PID controller examined to optimized using modified DE algorithm. However, in the Fuzzy-PID controller, the fuzzy logic algorithm is used to autotune the PID controller, but it cannot be considered as a fully real-time controller since the fuzzy algorithm uses a previous knowledge base built offline. The offline design of Fuzzy algorithm cannot cope with real-time unexpected vibrations occurred while driving car in different road profiles. In this paper, a Fuzzy-DE-PID controller proposed based on modified DE algorithm to enhance the Fuzzy logic gains in order to increase vehicle semi-active suspension system performance. To prove the effectiveness of the proposed controllers, a simulation and experimental tests were conducted using the proposed controller with different disturbances. The results of the simulation and the experimental tests for the proposed controller showed improvement of the vehicle’s ride comfort over the Fuzzy-PID and the passive system. We believe that using this proposed controller in any other real-time application will improve the performance to the highest levels without the need for a previous knowledge base for designing a real-time Fuzzy-PID controller.

Semi-active lateral control simulation of straddle-type monorail dynamic model with single-axle bogies

Lateral stability of straddle-type monorail vehicle (STMV) with single-axle bogies, as a new type of bogies, has been paid more and more attention. To solve it the lateral control method of a semi-active suspension system for STMV dynamic model with single-axle bogies based on magnetorheological fluid damper is proposed. The full-scale dynamics model of 34 freedom and magneto-rheological (MR) damper is established. An adaptive fuzzy hybrid strategy for STMV dynamic model based on vehicle body acceleration and velocity feedback is designed. The inverse mechanical model of MR damper is established to predict the control current. The dynamic characteristics of a semi-active suspension system based on MR damper model are studied by numerical method. The dynamic response of a STMV model with a semi-active suspension system is analysed. The simulation results show that the proposed adaptive control strategy can improve the comfort of the vehicle and improve the stability of the operation.

Characterization and quarter car analysis with magnetorheological fluid damper using modified algebraic model (mAlg)

Magnetorheological (MR) dampers have received the ever-increasing attention of many researchers considering their wide range of applications ranging from large seismic control of structures to prosthetics in the medical field. One such application is in semi-active vehicle suspension with MR damper. Modeling the dynamic behavior of MR damper is an intriguing challenge and many mathematical models are put forth to address this task. In this work, the MR damper is initially developed and characterized using in-house prepared MR fluid. This study aims at using a modified algebraic model (mAlg) for modeling the hysteretic behavior of the MR damper using experimental force data. Also, the study uses a Genetic algorithm toolbox to find optimal parameters for the mAlg model, and the accuracy of mAlg is visualized with various plots. The work also aims at analyzing the response of the quarter car model with MR damper to three kinds of road excitations using Simulink.

Monitoring of Liquid Viscosity for Viscous Dampers through a Wireless Impedance Measurement System

Viscous dampers are a type of seismic damping equipment widely used in high-rise buildings and bridges. However, the viscosity of the damping fluid inside the viscous damper will change over time during its use, which significantly reduces the seismic performance of the viscous damper. Hence, it is necessary to monitor the viscosity of the fluid inside the damper over its service life. In this paper, a damping fluid viscosity monitoring method based on wireless impedance measurement technology is proposed. A piezoelectric sensor is installed in a damper cylinder specimen, and the viscosity of the damping fluid is determined by measuring the piezoelectric impedance value of the sensor. In this study, 10 samples of damping fluids with different viscosities are tested. In order to quantitatively correlate damping fluid viscosity and electrical impedance, a viscosity index (VI) based on the root mean square deviation (RMSD) is proposed. The experimental results show that the variation of the real part in the impedance signal can qualitatively determine the damping fluid viscosity while the proposed VI can effectively and quantitatively identify the damping fluid viscosity.

Self-adapting model for variable stiffness magnetorheological dampers

Variable stiffness magnetorheological fluid (MRF) dampers inherently have special nonlinear characteristics and complex structures. An accurate model describing the nonlinearity is the key for the damper to operate under variable conditions. This paper proposes a self-adapting model to characterize the variable stiffness MRF dampers through corresponding optimized algorithm. The experimental results verify the capability of the self-adapting of the model parameters. The model can describe the nonlinear characteristics of the variable stiffness MRF damper when conditions are changed. The proposed self-adaptive model improves the model accuracy which provide an approach for modeling complex dampers under variable working conditions.

Semi‐active control of metal foam magnetorheological damper

AbstractA new type of foam metal magnetorheological damper is designed, and its performance in semi‐active control is investigated. At first, magnetorheological fluid is stored in the pore of metal foam, and with the action of magnetic field, magnetorheological fluid is extracted from metal foam, and then fills up the shear gap to produce magnetorheological effect. The magnetic field density in the shear gap is studied by the software Ansys finite element method, the magnetic flux density in the working gap is obtained in the different exciting current. A testing rig, including the vibration generator, laser displacement sensor, proportion integration differentiation control and cantilever beam, is built to investigate the semi‐active control performance of metal foam magnetorheological fluid damper. The result indicates that metal foam magnetorheological fluid damper has a good controllable damping property. When the exciting current is about compared with the vibration amplitude of cantilever beam magnetorheological fluid damper the vibration amplitude without foam metal magnetorheological fluid, the displacement of cantilever beam decreases by 44.4 %, which validates the semi‐active control effect of the foam metal magnetorheological fluid damper.

Earthquake Damage Reduction in Timber Frame Houses Using Small-Size Fluid Damper

Timber frame structures are common traditional methods of housing construction, which use squared-off timber beams, columns, and walls as lateral load-bearing members. The seismic performance of timber frame houses can be secured by the load-bearing capacity of erected braces and walls; however, past major earthquakes have caused severe damage to earthquake-resistant timber frame houses. This study investigates the effect of small-size fluid dampers on the earthquake damage reduction in a timber frame house through earthquake response analyses. A detailed analytical model was generated based on an actual two-story timber frame house, which was designed for the highest seismic grade using the latest Japanese standards. Time-history response analyses were carried out for the analytical model subjected to the 2016 Kumamoto earthquake with and without small-size fluid dampers. The small-size fluid damper is equipped with a relief mechanism for the damping force, and its damping property can be expressed using the Maxwell model. Four or seven fluid dampers were installed in the first story of the model to investigate their effect on the earthquake damage reduction. The results of the earthquake response analyses show that the four and seven fluid dampers can reduce the maximum first-story drift angle by approximately one-third and half, respectively. The dampers suppress the residual deformation, control the elongation of the fundamental period during the response, and restrain the amplitude growth. A small-size fluid damper has an equivalent quake resistance to a conventional structural wall with a wall ratio of 3 plus.