scholarly journals Full-Scale Simulations of Magnetorheological Damper for Implementation of Semi-Actively Structural Control

2018 ◽  
Vol 35 (4) ◽  
pp. 549-562 ◽  
Author(s):  
Y. B. Peng ◽  
Z. K. Zhang ◽  
J. G. Yang ◽  
L. H. Wang
Keyword(s):  
Structural Control ◽  
Low Cost ◽  
Excitation Frequency ◽  
Low Frequency ◽  
Mr Damper ◽  
Excitation Amplitude ◽  
Full Scale ◽  
Magnetorheological Damper ◽  
Input Current ◽  
Two Dimensional

ABSTRACTFull-scale simulations of a (Magnetorheological) MR damper are carried out for revealing its hysteretic behaviors associated with implementation of semi-active control using the routine of computational fluid dynamics. By virtue of the structural symmetry of the MR damper, a two-dimensional configuration for finite element simulation is built up. Herschel-Bulkley model is employed to represent the property of the MR fluid, of which the control parameters and their relevances to the input current are addressed. Typical cases involving sinusoidal and irregular displacements, steady and transient currents loaded upon the MR damper are investigated. Numerical investigations reveal that the damper force has a positive correlation with input current, excitation amplitude and excitation frequency. The full-scale simulation is proved to exhibit a sound accuracy through the validation of experimental data. It provides a logical manner revealing the true performance of MR dampers under desirable operating modes in practice, and can be readily integrated with the gain design of the associated semi-actively controlled structure. This progress bypasses the technical challenge inherent in the traditional tests with low-frequency cyclic loadings due to the limitation of experimental setup. Besides, comparative study between two-dimensional and three-dimensional configuration simulations of the MR damper shows that former has a better applicability, which can be carried out on a low-cost platform.

Magnetorheological (MR) Damping for Vibration Mitigation: Experimental Analysis

2015 ◽  
Author(s):  
Sudhir Kaul ◽  
William Deaton ◽  
Benjamin Stewart
Keyword(s):  
Smart Materials ◽  
Excitation Frequency ◽  
Time History ◽  
Mr Damper ◽  
Excitation Amplitude ◽  
Input Current ◽  
Vibration Mitigation ◽  
High Durability ◽  
Stiffness Constant ◽  
Industry Applications

Magnetorheological (MR) dampers have emerged as a viable means of semi-active damping in multiple industry applications. The semi-active nature of these dampers is a significant attribute since the damper functions as a passive damper in the event of a failure. While there have been other smart materials like ferroelectric, piezoelectric, shape memory alloys, etc. that have been successfully used, MR fluids exhibit a unique combination of completely reversible effect, very low response time, high durability and very low energy requirements that make them suitable for vibration control in a wide variety of applications. This paper presents results from an experimental investigation that has been carried out to evaluate the performance of a MR damper for vibration mitigation. The capability of a commercial MR damper to isolate a payload from base excitation is analyzed and the damper parameters are identified to simulate the capability of the damper with regards to transmissibility. Multiple iterations of testing are performed in order to evaluate the influence of variables such as input current to the electromagnet, mass of the payload, excitation frequency and excitation amplitude. Results indicate that the MR damper is successful in mitigating vibrations transmitted to the payload. Vibration mitigation is quantified through multiple means such as comparing the root mean square (RMS) of the time history of acceleration of the base with that of the payload, comparing the frequency response and evaluating the hysteresis plots. Displacement transmissibility results directly demonstrate the variable damping capability of the MR damper. Although the stiffness constant of the damper may also change, it is not seen to vary appreciably in this study since the excitation amplitude is limited to a low threshold. The damper is found to be robust with an inherent ability of handling payload and excitation variability. It is observed that increasing the input current to the electromagnet around the MR fluid results in an increase in damping, therefore, making the use of these dampers viable in applications where payloads and excitation inputs are expected to change during operation.

Nonreciprocal Wave Transmission in Metastable Modular Metastructures Utilizing Asymmetric Dual-Threshold Snap-Through

2019 ◽  
Author(s):  
Xiang Liu ◽  
Guoping Cai ◽  
K. W. Wang
Keyword(s):  
Potential Energy ◽  
Excitation Frequency ◽  
Excitation Amplitude ◽  
Wave Transmission ◽  
Dimensional Structure ◽  
Two Dimensional ◽  
One Dimensional ◽  
Threshold Phenomenon ◽  
Energy Equilibrium ◽  
Nonreciprocal Transmission

Abstract In this research, the nonreciprocal wave transmission features in one-dimensional and two-dimensional metastable modular metastructures are studied. Unlike previous work, in which the nonreciprocal transmission in metastable metastructures is realized by utilizing the supratransmission phenomenon when the excitation frequency is inside the linearized bandgap, a new approach is explored to achieve nonreciprocal wave transmission exploiting metastability and asymmetric dual-threshold snap-through. It is found that because of the asymmetry of potential energy wells of the equilibria, there will be two excitation amplitude thresholds for a metastable component when it is initially at the high-potential-energy equilibrium with excitation frequency within the passband. When the excitation amplitude increases and exceeds the first threshold, the metastable component will snap to the low-potential-energy equilibrium and maintain intrawell motion around this stable point, which will cause a significant decrease of the wave transmission. And when the excitation amplitude exceeds the second threshold, the metastable component will start to perform interwell motion, and now the wave transmission will increase suddenly. By using this “dual-threshold” phenomenon, nonreciprocal wave transmission in a one-dimensional structure is realized by connecting a metastable chain with a linear periodic part. Because of the wave attenuation effect of the linear part of the system, the excitation amplitude thresholds on different sides of the one-dimensional structure will be discrepant. Therefore, nonreciprocal wave transmission can be developed when the excitation amplitude is within certain ranges. It is interesting to note that the direction of nonreciprocal wave transmission can be changed by setting the excitation amplitude to different values. By changing the configuration of the metastable chain, the operation frequency and excitation amplitude ranges of the nonreciprocal transmission can be tuned. For a two-dimensional metastable metastructure, nonreciprocal wave transmission can be realized by adjusting the parameters of some metastable modules in the metastructure in the manner that the potential energy and energy thresholds of the adjusted modules and the unadjusted modules are different, but the passbands of the adjusted modules and the unadjusted modules will overlap in some frequency regions. Numerical studies provide clear insight of the proposed nonreciprocal wave transmission approach.

scholarly journals Experimental Study of a Variable Stiffness Seat Suspension Installed With a Compact Rotary MR Damper

2021 ◽  
Vol 8 ◽  
Author(s):  
Shuaishuai Sun ◽  
Jian Yang ◽  
Penghui Wang ◽  
Masami Nakano ◽  
Longjiang Shen ◽  
...  
Keyword(s):  
Ride Comfort ◽  
Excitation Frequency ◽  
Mr Damper ◽  
Variable Stiffness ◽  
Excitation Amplitude ◽  
Harmonic Excitation ◽  
Random Excitation ◽  
Shaking Table ◽  
Seat Suspension ◽  
Vibration Attenuation Performance

Traditional MR seat suspension without stiffness control is not able to avoid the resonance between the excitation and the seat, though it can dampen the vibration energy. To solve this problem, this paper proposed a variable stiffness (VS) magnetorheological (MR) damper to implement an advanced seat suspension. Its natural frequency can be shifted away from the excitation frequency through the variations of stiffness, thereby realizing the non-resonance control. The new seat suspension is designed and prototyped first, and then its dynamic property under different energizing current, excitation amplitude, and excitation frequency was tested using an MTS machine. The testing results verified its stiffness controllability. The vibration attenuation performance of the seat suspension was also evaluated on a vibration shaking table. The vibration reduction performance of the seat suspension was evaluated under two kinds of excitations, i.e., harmonic excitation and random excitation; the experimental results indicate that the new seat suspension outperforms passive seat suspensions regarding their ride comfort.

Testing and Modeling of MR Damper and Its Application to SDOF Systems Using Integral Backstepping Technique

2009 ◽  
Vol 131 (2) ◽  
Author(s):  
Sk. Faruque Ali ◽  
Ananth Ramaswamy
Keyword(s):  
Active Control ◽  
Testing Machine ◽  
Mr Damper ◽  
Control Device ◽  
Magnetorheological Damper ◽  
Input Current ◽  
Magnetorheological Dampers ◽  
Damper Control ◽  
Nonlinear Devices ◽  
Current Monitoring

Magnetorheological dampers are intrinsically nonlinear devices, which make the modeling and design of a suitable control algorithm an interesting and challenging task. To evaluate the potential of magnetorheological (MR) dampers in control applications and to take full advantages of its unique features, a mathematical model to accurately reproduce its dynamic behavior has to be developed and then a proper control strategy has to be taken that is implementable and can fully utilize their capabilities as a semi-active control device. The present paper focuses on both the aspects. First, the paper reports the testing of a magnetorheological damper with an universal testing machine, for a set of frequency, amplitude, and current. A modified Bouc–Wen model considering the amplitude and input current dependence of the damper parameters has been proposed. It has been shown that the damper response can be satisfactorily predicted with this model. Second, a backstepping based nonlinear current monitoring of magnetorheological dampers for semi-active control of structures under earthquakes has been developed. It provides a stable nonlinear magnetorheological damper current monitoring directly based on system feedback such that current change in magnetorheological damper is gradual. Unlike other MR damper control techniques available in literature, the main advantage of the proposed technique lies in its current input prediction directly based on system feedback and smooth update of input current. Furthermore, while developing the proposed semi-active algorithm, the dynamics of the supplied and commanded current to the damper has been considered. The efficiency of the proposed technique has been shown taking a base isolated three story building under a set of seismic excitation. Comparison with widely used clipped-optimal strategy has also been shown.

Experiment Investigation of Magnetorheological Damper for High Impulsive Load

2010 ◽  
Author(s):  
Zhaochun Li ◽  
Jiong Wang
Keyword(s):  
Low Frequency ◽  
Mr Damper ◽  
Magnetorheological Damper ◽  
The Novel ◽  
Low Velocity ◽  
Impulsive Load ◽  
Signal Process ◽  
Impulsive Input ◽  
New Type ◽  
Long Stroke

In the past decade, magnetorheological (MR) damper, as a new type of smart damper, has gained significant findings which have led to good applications in the field of engineering. However, most of these work focused on low velocity and low frequency applications. This study provides an experimental investigation into a self-designed MR damper subject to high impulsive load. First of all, the active force of the recoil system in weapons is selected as an impulsive input of the MR damper. Then, a MR damper with long stroke of 440mm and single-ended construction especially for impact and high velocity is designed. The novel recoil apparatus is mainly composed of a MR damper and a series of springs. The measurement system includes transducers and the corresponding signal process equipments. Under the firing impulsive load, three currents including 1.0A, 1.5A and 2.0A are investigated. The results show that the peak force becomes larger when the current increases. On the other hand, the MR fluid is uncontrollable when velocity rises rapidly and it is not controllable until 0.026s.

A twisting vibration based energy harvester for ultra-low frequency excitations

2020 ◽  
Vol 64 (1-4) ◽  
pp. 693-700
Author(s):  
Kangqi Fan ◽  
Hengheng Qu ◽  
Meiling Cai
Keyword(s):  
Outer Surface ◽  
Potential Application ◽  
Energy Harvester ◽  
Excitation Frequency ◽  
Low Frequency ◽  
Excitation Amplitude ◽  
Human Hand ◽  
Initial Angle ◽  
Surrounding Environment ◽  
Vibration Of A String

Ultra-low frequency mechanical excitations are omnipresent in our surrounding environment, but the efficient exploitation of them is generally difficult because they normally drive the widely reported cantilevered harvesters to work under non-resonant conditions. Although the frequency up-conversion strategy has been proposed to mitigate this issue, it usually leads to complicated structures. This paper reports a novel energy harvesting approach based on the twisting vibration of a string-driven rotor. To examine the feasibility of this approach, an electromagnetic energy harvester is designed, which is composed of a lid, a rotor with embedded magnets, a pendant, and a tube with pick-up coils attached to the outer surface. The rotor is suspended between the lid and the pendant through a piece of string, and then actuated by the ambient excitations through the string. Under the excitations produced by a crank-slider mechanism, the designed harvester can generate useful electric outputs that are proportional to the excitation amplitude, the initial angle between the pendant and lid, and the excitation frequency. Moreover, the harvester can also provide 0.034 mW power when it is periodically pulled by the human hand at approximately 1 Hz. This study demonstrates the potential application of the string-driven rotor in collecting energy from ultra-low frequency excitations.

Parameter identification of modified Bouc–Wen model and analysis of size effect of magnetorheological dampers

2017 ◽  
Vol 29 (7) ◽  
pp. 1464-1480 ◽  
Author(s):  
Yongbo Peng ◽  
Jinggui Yang ◽  
Jie Li
Keyword(s):  
Size Effect ◽  
Performance Test ◽  
Functional Relationship ◽  
Excitation Frequency ◽  
Magnetorheological Damper ◽  
Input Current ◽  
Smart Devices ◽  
Model Parameters ◽  
Magnetorheological Dampers ◽  
Large Size

Magnetorheological damper is one of the most promising smart devices for vibration mitigation of structures subjected to dynamic loads. In order to fulfill the value of magnetorheological damping control, a feasible mechanical model of magnetorheological dampers with simplicity and sufficient accuracy is usually required in practice. It comes up, however, with a challenging issue for the modeling of large-size magnetorheological dampers due to physical constraints on the performance test. The large-size magnetorheological damper is typically modeled in up-scaling parameters associated with models of the small-size magnetorheological damper. This treatment remains open since a size effect hinges upon the intrinsic non-linearity inherent in the device. In this article, a dynamic test of a small-size magnetorheological damper is performed first. The relevance of damper force with the input current and excitation frequency is well revealed. The modified Bouc–Wen model is employed to logically represent the dynamic behaviors of magnetorheological dampers. Identification of model parameters in typical loading cases is then proceeded, of which the functional relationship against input current is established. The size effect of magnetorheological dampers is further addressed through investigating the functional relationship relevant to maximum outputs of 200, 10, and 5 kN. It is indicated that the small-size magnetorheological damper needs more number of control parameters than the large-size magnetorheological damper. Moreover, a linear current relevance of model parameters appears in the small-size magnetorheological damper, while a quadratic current relevance of model parameters appears in the large-size magnetorheological damper. Size effect of magnetorheological dampers arises to be well-marked in the range of low current and becomes unapparent in the range of high current. Besides, the validation of modified Bouc–Wen model is carried out that reveals the applicability of the model with case-optimized parameters.

Structure-Excitation Modal Decoupling by Modification of the Involved Acoustic Modes of the Sound Insulating Enclosure

2001 ◽  
Author(s):  
Christos I. Papadopoulos ◽  
Ioannis T. Georgiou
Keyword(s):  
Feasible Solution ◽  
Excitation Frequency ◽  
Low Frequency ◽  
Excitation Amplitude ◽  
Acoustic Response ◽  
Noise Sources ◽  
Acoustic Modes ◽  
Band Noise ◽  
Simultaneous Control ◽  
Narrow Frequency Band

Abstract Several noise sources such as machinery with rotating or reciprocating parts routinely produce high levels of noise in narrow frequency ranges lying in the neighbourhood of the rotating or reciprocating frequency and their harmonics. When enclosures are used to isolate such noise sources, peak response might be observed at these frequency ranges due both to increased excitation amplitude and resonating phenomena caused by the interaction of the excitation with the acoustic modes of the enclosure. Especially in the low frequency range and for low or intermediate wall absorption, the acoustic response of the enclosure is modal and these peak responses can be intense. This paper proposes a methodology to minimize the effect of narrow-frequency-band noise by redistribution of the acoustic modes of the insulating enclosure. This can be achieved by shifting the enclosure acoustic modes away from the excitation frequency so as to make superimposed resonating phenomena less intense. For that, several variable geometric modifications of the enclosure walls are introduced. The magnitude of those modifications that will lead to sparse mode distribution in the neighbourhood of the excitation frequency is estimated by means of a combined finite element-optimisation method. The above methodology is applied to an orthogonal enclosure and two different narrow-band loads in the neighbourhood of 90 and 120 Hz are studied. It is shown that, for each frequency load, a feasible set of geometric modifications can be found so as for the neighbouring modes to be shifted and, consecutively, for resonating effects to be made less intense. Furthermore it is shown that feasible solution to the problem of simultaneous control of noise having two or more intense excitation frequencies is also attainable.

Research on the low-frequency pressure generator based on magnetic fluid

2019 ◽  
Vol 33 (16) ◽  
pp. 1950173 ◽  
Author(s):  
Wenrong Yang ◽  
Yao Zhai ◽  
Xiaorui Yang
Keyword(s):  
Magnetic Field ◽  
Magnetic Fluid ◽  
Excitation Frequency ◽  
Low Frequency ◽  
Magnetic Core ◽  
Input Current ◽  
Manufacturing Cost ◽  
Solenoid Coil ◽  
Output Pressure ◽  
Pressure Generator

To solve the problems that the existing pressure generators require high mechanical excitation frequency, need large manufacturing cost and are hard to control, a kind of pressure generator with low-frequency based on magnetic fluid is proposed in this paper. Magnetic fluid possesses the advantages of both magnetism of solid magnetic material and fluidity of liquid. The first-order buoyancy of magnetic fluid changes with low frequency alternating magnetic field. Based on this, the superimposed magnetic field is generated by electrifying the conical solenoid coil connected with the long solenoid coil with magnetic core in parallel. Magnetic field and magnetic force in the model are analyzed, then the relationship between input current and output pressure is calculated. In addition, the experimental platform is built and the performance of the device is tested. The result shows that the pressure generator can produce the corresponding pressure signal according to the input current.

Performance tests and mathematical model considering magnetic saturation for magnetorheological damper

2012 ◽  
Vol 23 (12) ◽  
pp. 1331-1349 ◽  
Author(s):  
Zhao-Dong Xu ◽  
Da-Huan Jia ◽  
Xiang-Cheng Zhang
Keyword(s):  
Mathematical Model ◽  
Excitation Frequency ◽  
Experimental Results ◽  
Displacement Amplitude ◽  
Magnetorheological Damper ◽  
Input Current ◽  
Magnetic Flux Density ◽  
Magnetic Saturation ◽  
Loading Frequency ◽  
Magnetorheological Dampers

As a semiactive control device, magnetorheological dampers have been paid more attention due to their high controllability, fast response, and low power demand. One of the important characteristics for magnetorheological dampers is magnetic saturation, that is, the maximum damping force will reach some value and no longer vary with the increasing input current, especially in the presence of large magnetic flux density. In order to take this problem into account fully, tests on a shear-valve mode magnetorheological damper are carried out to consider the effects of input current, displacement amplitude, and loading frequency on the properties of the magnetorheological damper during magnetic saturation situation first. Then, the magnetic saturation phenomenon of the magnetorheological damper is simulated using the finite element method, and the numerical simulation results are compared with the experimental results. Finally, a magnetic saturation mathematical model is proposed to describe the properties of the magnetorheological damper, and the numerical hysteresis curves of the proposed magnetic saturation mathematical model, the Bingham model, and the Bouc–Wen model are compared with the experimental results. It can be concluded that the magnetic saturation mathematical model can describe the influence of input current, displacement amplitude, and excitation frequency on the properties and the magnetic saturation property of the magnetorheological damper.

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