A Squeeze-Flow Mode Magnetorheological Mount: Design, Modeling, and Experimental Evaluation

2012 ◽  
Vol 134 (2) ◽  
Author(s):  
T. M. Nguyen ◽  
C. Ciocanel ◽  
M. H. Elahinia
Keyword(s):  
Vibration Isolation ◽  
Magnetic Circuit ◽  
Dynamic Stiffness ◽  
Experimental Results ◽  
Squeeze Flow ◽  
Design Parameters ◽  
Flow Mode ◽  
Wide Range ◽  
Isolation Device ◽  
Stiffness And Damping

This paper presents a dual-mode magnetorheological (MR) fluid mount. Combining the fluid’s flow and squeeze modes of operation gives this MR mount a unique possibility for varying dynamic stiffness and damping. Details on the design of the internal structure of the mount and the magnetic circuit are provided. Simulation and experimental results are presented to show the effectiveness of the magnetic circuit. A mathematical model that combines the behavior of the fluid and the elastomeric parts and takes into account the magnetic activation of the fluid is used to gauge the effect of design parameters on the isolation characteristics of the mount. Experimental results show that in the proposed design, the dynamic stiffness of the mount may be varied over a wide range of frequencies making the mount a unique and versatile vibration isolation device for cases where input excitation occurs over a wide range of frequencies.

On the Design and Control of a Squeeze-Flow Mode Magnetorheological Fluid Mount

2007 ◽  
Author(s):  
Constantin Ciocanel ◽  
The Nguyen ◽  
Christopher Schroeder ◽  
Mohammad Elahinia
Keyword(s):  
Vibration Isolation ◽  
Hybrid Control ◽  
Control Strategies ◽  
Dynamic Stiffness ◽  
Squeeze Flow ◽  
Flow Mode ◽  
Force Transmissibility ◽  
Displacement Force ◽  
Vertical Vibrations ◽  
And Control

The paper presents the design and control of a magnetorheological (MR) fluid based mount that combines the squeeze and flow modes in operation. The proposed design yields a high static stiffness and a low dynamic stiffness in the working frequency range of the mount, enhancing the vibration isolation capabilities of the mount compared to existing hydraulic mounts. Vertical vibrations, namely displacement/force transmissibility, can be isolated or significantly reduced, in real time, by controlling the fluid yield stress through an applied electric current. The mount governing equations have been derived and the effect of system parameters on its performance was analyzed. Preliminary results on the implementation of skyhook, groundhook and hybrid control strategies are also presented.

The Surface Roughness Effect on the Dynamic Stiffness and Damping Characteristics of the Hydrostatic Thrust Spherical Bearings: Part 5 of 5 — Clearance Type of Bearings

2007 ◽  
Author(s):  
Ahmad W. Yacout
Keyword(s):  
Surface Roughness ◽  
Capillary Tube ◽  
Dynamic Stiffness ◽  
Dynamic Performance ◽  
Major Effect ◽  
Design Parameters ◽  
Compressibility Effect ◽  
Damping Coefficients ◽  
Stiffness And Damping ◽  
Fluid Compressibility

This study has theoretically analyzed the surface roughness, centripetal inertia and recess volume fluid compressibility effects on the dynamic behavior of a restrictor compensated hydrostatic thrust spherical clearance type of bearing. The stochastic Reynolds equation, with centripetal inertia effect, and the recess flow continuity equation with recess volume fluid compressibility effect have been derived to take into account the presence of roughness on the bearing surfaces. On the basis of a small perturbations method, the dynamic stiffness and damping coefficients have been evaluated. In addition to the usual bearing design parameters the results for the dynamic stiffness and damping coefficients have been calculated for various frequencies of vibrations or squeeze parameter (frequency parameter) and recess volume fluid compressibility parameter. The study shows that both of the surface roughness and the centripetal inertia have slight effects on the stiffness coefficient and remarkable effects on the damping coefficient while the recess volume fluid compressibility parameter has the major effect on the bearing dynamic characteristics. The cross dynamic stiffness showed the bearing self-aligning property and the ability to oppose whirl movements. The orifice restrictor showed better dynamic performance than that of the capillary tube.

Vibration isolation using a magnetorheological damper in the squeeze-flow mode

1999 ◽  
Author(s):  
Neil D. Sims ◽  
Roger Stanway ◽  
Andrew R. Johnson ◽  
J. S. Yang
Keyword(s):  
Vibration Isolation ◽  
Magnetorheological Damper ◽  
Squeeze Flow ◽  
Flow Mode

ER fluids in the squeeze-flow mode: an application to vibration isolation

1992 ◽  
Vol 28 (1) ◽  
pp. 89-94 ◽  
Author(s):  
R. Stanway ◽  
J.L. Sproston ◽  
M.J. Prendergast ◽  
J.R. Case ◽  
C.E. Wilne
Keyword(s):  
Vibration Isolation ◽  
Squeeze Flow ◽  
Flow Mode ◽  
Er Fluids

scholarly journals Dynamically variable negative stiffness structures

2016 ◽  
Vol 2 (2) ◽  
pp. e1500778 ◽  
Author(s):  
Christopher B. Churchill ◽  
David W. Shahan ◽  
Sloan P. Smith ◽  
Andrew C. Keefe ◽  
Geoffrey P. McKnight
Keyword(s):  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Low Frequency ◽  
Variable Stiffness ◽  
Negative Stiffness ◽  
Load Bearing ◽  
Vibration Isolators ◽  
Wide Range ◽  
Engineered Systems ◽  
Tunable Stiffness

Variable stiffness structures that enable a wide range of efficient load-bearing and dexterous activity are ubiquitous in mammalian musculoskeletal systems but are rare in engineered systems because of their complexity, power, and cost. We present a new negative stiffness–based load-bearing structure with dynamically tunable stiffness. Negative stiffness, traditionally used to achieve novel response from passive structures, is a powerful tool to achieve dynamic stiffness changes when configured with an active component. Using relatively simple hardware and low-power, low-frequency actuation, we show an assembly capable of fast (<10 ms) and useful (>100×) dynamic stiffness control. This approach mitigates limitations of conventional tunable stiffness structures that exhibit either small (<30%) stiffness change, high friction, poor load/torque transmission at low stiffness, or high power active control at the frequencies of interest. We experimentally demonstrate actively tunable vibration isolation and stiffness tuning independent of supported loads, enhancing applications such as humanoid robotic limbs and lightweight adaptive vibration isolators.

Negative stiffness devices for vibration isolation applications: A review

2020 ◽  
Vol 23 (8) ◽  
pp. 1739-1755 ◽  
Author(s):  
Huan Li ◽  
Yancheng Li ◽  
Jianchun Li
Keyword(s):  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Structural Type ◽  
Research Area ◽  
Structure Design ◽  
Negative Stiffness ◽  
System Stability ◽  
Current State ◽  
Beam Type ◽  
Isolation Device

In recent years, negative stiffness vibration isolation device with nonlinear characteristic has become an emerging research area and attracted a significant amount of attentions in the community due to the promising potentials it brought into the field. Its high-static-low-dynamic stiffness property endows the capacity to realize effective vibration isolation and in the meantime to maintain the system stability. This article presents a comprehensive review of the recent research and developments on negative stiffness vibration isolation device. It begins with an introduction on the concept of negative stiffness and then provides a summary and discussion regarding the realization and characteristics of negative stiffness vibration isolation device. The article places its special interest on the principles, structure design, and device characterisation of different types of negative stiffness vibration isolation devices, including spring type, pre-bucked beam type, magnetism type, geometrically nonlinear structural type, and composite structural type. Besides, the applications of negative stiffness vibration isolation device, as well as negative stiffness damper, are summarized and discussed based on the current state-of-the-art. Finally, the conclusions and further discussion provide highlights of the investigation.

Experimental Verification of Controllability of a Mixed Mode MR Fluid Mount

2011 ◽  
Author(s):  
Shuo Wang ◽  
Mohammad Elahinia ◽  
The Nguyen
Keyword(s):  
Mixed Mode ◽  
Alternative Energy ◽  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Hybrid Vehicles ◽  
Flow Mode ◽  
Shear Mode ◽  
Mr Fluid ◽  
Set Up ◽  
Different Levels

With the advent of alternative energy and hybrid vehicles come new vibration problems and challenges that require nontraditional solutions. Semi-active vibration isolation devices are preferred to address the problem due to their effectiveness and affordability. A magnetorheological (MR) fluid mount can provide effective vibration isolation for applications such as hybrid vehicles. The MR fluid can produce different levels of damping when exposed to different levels of magnetic field. The fluid can be working in three modes which are the flow mode, shear mode and squeeze mode. A mixed mode MR fluid mount was designed to operate in a combination of the flow mode and the squeeze mode. Each of the working modes and the combined working mode has been studied. The mount’s performance has been verified in simulation and experiments. Based on the simulation and experimental results, it can be seen that the mount can provide a large range of dynamic stiffness. Given this range of dynamic stiffness, a controller has been designed to achieve certain dynamic stiffness at certain frequencies. The experiments are set up to realize the hardware-in-the-loop tests. Results from the experiments show that the mixed mode MR fluid mount is able to achieve desired dynamic stiffness which is directly related to vibration transmissibility.

Dynamic Characteristics Research of Magneto-Rheological Fluid Engine Mount

2015 ◽  
Vol 752-753 ◽  
pp. 913-917
Author(s):  
Gong Yu Pan ◽  
Qian Qian Wang ◽  
Xin Yang
Keyword(s):  
Dynamic Characteristics ◽  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Simulation Software ◽  
New Type ◽  
Engine Mount ◽  
Magneto Rheological ◽  
Stiffness And Damping ◽  
Vibration Isolation Performance ◽  
Isolation Performance

In order to improve the vibration isolation performance of engine mount, a new type of magneto-rheological semi-active mount with multiple inertia tracks is designed based on the existing magneto-rheological semi-active mount . The mechanical model is established according to the mount. The expression of the dynamic stiffness and damping lag angle is deduced, then the dynamic characteristics is simulated in the simulation software. At the same time, verify this model correct by the experiments.

Performance of an Adaptive Magnetorheological Fluid Mount

2007 ◽  
Author(s):  
Constantin Ciocanel ◽  
The Nguyen ◽  
Christopher Schroeder ◽  
Mohammad H. Elahinia
Keyword(s):  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Magnetorheological Fluid ◽  
Flow Mode ◽  
Frequency Range ◽  
Governing Equations ◽  
Mr Fluid ◽  
System Parameters ◽  
Force Transmissibility ◽  
Working Frequency

The paper investigates the response of a magnetorheological (MR) fluid based mount that combines the squeeze and flow modes in operation. The mount governing equations are introduced and the effect of system parameters on its performance is analyzed. The proposed design yields a high static and a low dynamic stiffness in the working frequency range of the mount. The overall vibration isolation characteristic of the mount is enhanced if compared to that of existing hydraulic mounts. Displacement and/or force transmissibility can be isolated or significantly reduced, in real time, by controlling the MR fluid yield stress. An embedded electromagnet is used to activate the MR fluid that can work in either squeeze or flow modes, or in both simultaneously. The results indicate that the flow mode is less effective in reducing transmissibility than the squeeze mode. However, when the flow and squeeze modes are both activated, the effect of the flow mode becomes more obvious.

Vibration Isolation of Rotating Machinery by Parameters Switched Magnetic Bearing and High Static Low Dynamic Stiffness Supports

2018 ◽  
Author(s):  
Yanhui Ma ◽  
Yixin Su ◽  
Suyuan Yu
Keyword(s):  
Rotational Speed ◽  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Design Strategy ◽  
Magnetic Bearing ◽  
Rotating Machinery ◽  
Control Parameters ◽  
Rotor Speed ◽  
Vibration Transmission ◽  
Stiffness And Damping

Vibrations in rotating machinery cause many problems such as excessive noise and the vibration transmission to the supporting structure. In addition, the vibration isolation of the machinery with a wide range of rotational speed is a vital requirement and different to realize in practical engineering. As one of the key components in rotating machinery, bearing is not only the major vibration excitation source, but also the main vibration transmission path. Therefore, the mechanical property of the bearing has a significant effect on the vibration of the rotating machinery. Compared with traditional mechanical bearing, the equivalent stiffness and damping of magnetic bearing can be changed by adjusting its control parameters. On this basis, a novel design strategy of parameters switched magnetic bearing and high static low dynamic stiffness (HSLDS) supports for the vibration isolation of rotating machinery is proposed in this article. The design changes the equivalent linear stiffness and damping of the magnetic bearing by adjusting the control parameters according to the rotor speed, which will improve the vibration isolation capability of magnetic bearing at different rotor speed. Meanwhile, to further reduce the vibration transmission, the rotating machinery was suspended by nonlinear isolator with high static low dynamic stiffness characteristic. As an example, a rotating machinery system consisting of a rigid rotor supported by parameters switched magnetic bearings and high static low dynamic stiffness supports is studied. In this model, the rotor is excited by the unbalance force with different rotational speed. The amplitude of force acted on the base and the maximum relative displacement between the journal and the bearing are used to judge the isolation performance. Simulation results show that the demonstrated the effectiveness of this design strategy and the force transmission is significantly reduced with a wide rotational speed range.

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