Design and Analysis of a Magnetorheological Fluid Mount Featuring Uni-Directional Squeeze Mode

2015 ◽  
Author(s):  
Xian-Xu Bai ◽  
Peng Chen ◽  
Li-Jun Qian ◽  
Ping Kan
Keyword(s):  
Dynamic Stiffness ◽  
Magnetorheological Fluid ◽  
Relative Displacement ◽  
Bottom Surface ◽  
Damping Properties ◽  
Damping Force ◽  
Equivalent Damping ◽  
Engine Vibration ◽  
Coil Winding ◽  
Stiffness And Damping

A magnetorheological fluid (MRF) mount featuring unidirectional squeeze mode for vehicle engine mounting system is proposed and designed to attenuate the engine vibration with characteristics of broadband and small amplitude. The MRF mount is comprised of upper and lower bases for installation, a main rubber for static load, a bobbin for electromagnetic coil winding and a squeeze plate. The bottom surface of the bobbin and the top surface of the squeeze plate form the polar plates, between which the MRF is squeezed during the rebound of the MRF mount. Combining dynamic stiffness property of passive hydraulic mounts without fluid and adjustable damping force of MRF at squeeze mode, the MRF mount could provide a unique variable dynamic stiffness and damping properties, by adjusting the exciting current. To evaluate the performance of the MRF mount, a mathematical model considering the behavior of MRF at squeeze mode is derived to theoretically analyze and numerically simulate the dynamic stiffness and equivalent damping properties of the MRF mount. Further, the MRF mount based quarter vehicle mounting system model considering suspension system is constructed to analyze the force transmissibility of engine mounting system in frequency domain and simulate the relative displacement response in time domain.

Porous Wall Gas Lubricated Journal Bearings: Theoretical Investigation

1979 ◽  
Vol 101 (4) ◽  
pp. 458-465 ◽  
Author(s):  
E. P. Gargiulo
Keyword(s):  
Experimental Investigation ◽  
Dynamic Stiffness ◽  
Porous Wall ◽  
Companion Paper ◽  
Journal Bearings ◽  
Damping Properties ◽  
Governing Equations ◽  
Performance Curves ◽  
Unsteady Characteristics ◽  
Stiffness And Damping

A model has been developed to compute the dynamic stiffness and damping properties of externally pressurized, porous-wall, gas journal bearings which includes the effects of journal rotation and eccentricity. This paper presents the derivation of the governing equations and the perturbation analysis used to find the unsteady characteristics. Typical nondimensional performance curves are found and the influences of seven governing parameters are discussed. A companion paper describes an experimental investigation of porous journal bearings.

scholarly journals Dynamic Performance of Laminated High-Damping and High-Stiffness Composite Structure Composed of Metal Rubber and Silicone Rubber

Materials ◽  
2021 ◽  
Vol 14 (1) ◽  
pp. 187
Author(s):  
Xiaoyuan Zheng ◽  
Zhiying Ren ◽  
Liangliang Shen ◽  
Bin Zhang ◽  
Hongbai Bai
Keyword(s):  
Silicone Rubber ◽  
Composite Structure ◽  
Dynamic Stiffness ◽  
Damping Properties ◽  
Damping Characteristics ◽  
Vibration Excitation ◽  
Metal Rubber ◽  
Damping Materials ◽  
Stiffness And Damping ◽  
Laminated Structures

In this study, a laminated composite damping structure (LCDS) with metal rubber (MR) as matrix and silicone rubber (SR) as reinforcement has been designed. The embedded interlocking structure formed by the multi-material interface of the LCDS can effectively incorporate the high damping characteristics of traditional polymer damping materials and significantly enhance the adjustable stiffness of the damping structure. Based on the periodic cyclic vibration excitation, dynamic tests on different laminated structures were designed, and the damping performance and fatigue characteristics under periodic vibration excitation of the LCDS, based on MR and SR, were explored in depth. The experimental results exhibited that, compared to single-compound damping structures, the LCDS with SR as reinforcement and MR as matrix has excellent stiffness and damping characteristics. The incorporation of the silicon-based reinforcement can significantly improve the performance of the entire structure under cyclic fatigue vibration. In particular, the effects of material preparation and operating parameters on the composite structure are discussed. The effects of MR matrix density, operating frequency, amplitude, and preload on the stiffness and damping properties of the MR- and SR-based LCDS were investigated by the single factor controlled variable method. The results demonstrated that the vibration frequency has little effect on the LCDS damping performance. By increasing the density of the MR matrix or increasing the structural preload, the energy dissipation characteristics and damping properties of the LCDS can be effectively improved. With the increase in vibration excitation amplitude, the energy consumption of the LCDS increases, and the average dynamic stiffness changes at different rates, resulting in the loss factor decreasing first and then increasing. In this study, a damping structure suitable for narrow areas has been designed, which overcomes the temperature intolerance and low stiffness phenomena of traditional polymer rubber materials, and provides effective guidance for the design of damping materials with controllable high damping and stiffness.

Experimental Investigation of Dynamic Normal Characteristics of Machined Joint Surfaces

2000 ◽  
Vol 122 (4) ◽  
pp. 393-398 ◽  
Author(s):  
W. P. Fu ◽  
Y. M. Huang ◽  
X. L. Zhang ◽  
Q. Guo
Keyword(s):  
Experimental Investigation ◽  
Dynamic Characteristics ◽  
Static Pressure ◽  
Dynamic Stiffness ◽  
Relative Displacement ◽  
Test Range ◽  
Joint Surfaces ◽  
Exciting Frequency ◽  
Stiffness And Damping Coefficient ◽  
Stiffness And Damping

This paper presents an experimental investigation on the normal dynamic characteristics of several machined joint surfaces, i.e., the varying principle of the normal dynamic stiffness and damping with exciting frequency, relative displacement and static pre-load under different joint conditions, including joint materials, mediums, machining methods and surface roughness, etc.. The joint parameters are extracted from experimental data by establishing the theoretical model of the joint surfaces, and the mechanism is analyzed qualitatively. The studied results show that, in the test range of this paper, the stiffness and damping coefficient of the joint surfaces increase with the static pre-load; the stiffness for a dry joint is independent of the exciting frequency, while the damping coefficients for both a dry and an oiled joint decrease with the exciting frequency; little relative displacement has no marked effect on the dynamic characteristics. The amount of influence of exciting frequency and static pressure is related to the joint conditions. [S0739-3717(00)00804-7]

Magnetorheological semi-active mount system for engines: Prototyping and testing

2020 ◽  
Vol 234 (13) ◽  
pp. 3081-3094
Author(s):  
Qing Liu ◽  
Guo-Dong Bai ◽  
Zhi-Hao Liu ◽  
Xian-Xu ‘Frank’ Bai ◽  
Hao Du ◽  
...  
Keyword(s):  
Fuzzy Controller ◽  
Mechanical Energy ◽  
Dynamic Stiffness ◽  
Experimental Tests ◽  
Damping Force ◽  
Mr Fluid ◽  
Theoretical Simulation ◽  
Structural Principle ◽  
Mr Damping ◽  
Coil Winding

In order to maximize the controllability of magnetorheological (MR) mount for engines, a novel (MR) mount with an internal bypass (MRM-IB), which provides particular advantages of large dynamic stiffness range, small field-off dynamic stiffness and long available stroke under full vibration frequency range, is proposed and investigated in this paper. The proposed MRM-IB consists of a main rubber spring unit for supporting static load and a MR damping unit for mechanical energy dissipation. The MR damping unit is composed of a piston assembly, a MR fluid chamber and an annular MR fluid channel sandwiched by two concentric cylinders, that is, the inner and outer cylinders. Electromagnetic coil winding is wound on the outside of the inner cylinder and continuous damping/dynamic stiffness of the MRM-IB is tuned by the applied current in the coils. Structural principle of the magnetic circuit of the proposed MRM-IB is validated and analyzed, and the mathematical model of the controllable damping force is then established. In addition, a frequency-based piecewise controller and a fuzzy controller for a specific MR semi-active automotive mount system are designed, and the theoretical simulation and the experimental tests of the system are conducted, compared and analyzed.

Dynamic stiffness and damping properties of elastic elements with reinforced-composite coverings

1986 ◽  
Vol 18 (2) ◽  
pp. 225-227
Author(s):  
B. L. Pelekh ◽  
B. I. Salyak ◽  
I. S. Kogut ◽  
A. Yu. Mykita
Keyword(s):  
Dynamic Stiffness ◽  
Damping Properties ◽  
Reinforced Composite ◽  
Stiffness And Damping ◽  
Elastic Elements

scholarly journals Development of a novel variable stiffness and damping magnetorheological fluid damper

2015 ◽  
Vol 24 (8) ◽  
pp. 085021 ◽  
Author(s):  
Shuaishuai Sun ◽  
Jian Yang ◽  
Weihua Li ◽  
Huaxia Deng ◽  
Haiping Du ◽  
...  
Keyword(s):  
Variable Stiffness ◽  
Magnetorheological Fluid ◽  
Magnetorheological Fluid Damper ◽  
Fluid Damper ◽  
Stiffness And Damping

Dynamic characteristics of squeeze-type mount using magnetorheological fluid

2005 ◽  
Vol 219 (1) ◽  
pp. 27-34 ◽  
Author(s):  
Y K Ahn ◽  
J-Y Ha ◽  
Y-H Kim ◽  
B-S Yang ◽  
M Ahmadian ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
Experimental Analysis ◽  
Vibration Isolation ◽  
Dynamic Behaviour ◽  
Electrical Current ◽  
Magnetorheological Fluid ◽  
Test Set ◽  
Mr Fluid ◽  
Set Up ◽  
Stiffness And Damping

This paper presents an analytical and experimental analysis of the characteristics of a squeeze-type magnetorheological (MR) mount which can be used for various vibration isolation areas. The concept of the squeeze-type mount and details of the design of a squeeze-type MR mount are discussed. These are followed by a detailed description of the test set-up for evaluating the dynamic behaviour of the mount. A series of tests was conducted on the prototype mount built for this study, in order to characterize the changes occurring as a result of changing electrical current to the mount. The results of this study show that increasing electrical current to the mount, which increases the yield stress of the MR fluid, will result in an increase in both stiffness and damping of the mount. The results also show that the mount hysteresis increases with increase in current to the MR fluid, causing changes in stiffness and damping at different input frequencies.

Design and structural performance measurements of a novel multi-cantilever foil bearing

2014 ◽  
Vol 229 (10) ◽  
pp. 1830-1838 ◽  
Author(s):  
Kai Feng ◽  
Xueyuan Zhao ◽  
Zhiyang Guo
Keyword(s):  
Dynamic Characteristics ◽  
Dynamic Load ◽  
Dynamic Stiffness ◽  
Excitation Frequency ◽  
Viscous Damping ◽  
Equivalent Viscous Damping ◽  
Foil Bearing ◽  
Load Tests ◽  
Stiffness And Damping ◽  
Motion Amplitude

With increasing need for high-speed, high-temperature, and oil-free turbomachinery, gas foil bearings (GFBs) have been considered to be the best substitutes for traditional oil-lubricated bearings. A multi-cantilever foil bearing (MCFB), a novel GFB with multi-cantilever foil strips serving as the compliant underlying structure, was designed, fabricated, and tested. A series of static and dynamic load tests were conducted to measure the structural stiffness and equivalent viscous damping of the prototype MCFB. Experiments of static load versus deflection showed that the proposed bearing has a large mechanical energy dissipation capability and a pronounced nonlinear static stiffness that can prevents overly large motion amplitude of journal. Dynamic load tests evaluated the influence of motion amplitude, loading orientation and misalignment on the dynamic stiffness and equivalent viscous damping with respect to excitation frequency. The test results demonstrated that the dynamic stiffness and damping are strongly dependent on the excitation frequency. Three motion amplitudes were applied to the bearing housing to investigate the effects of motion amplitude on the dynamic characteristics. It is noted that the bearing dynamic stiffness and damping decreases with incrementally increasing motion amplitudes. A high level of misalignment can lead to larger static and dynamic bearing stiffness as well as to larger equivalent viscous damping. With dynamic loads applied to two orientations in the bearing midplane separately, the dynamic stiffness increases rapidly and the equivalent viscous damping declines slightly. These results indicate that the loading orientation is a non-negligible factor on the dynamic characteristics of MCFBs.

Nonlinear Isolator Optimization Using RMS Cost Function

2004 ◽  
Author(s):  
A. Narimani ◽  
M. F. Golnaraghi
Keyword(s):  
Closed Form Solution ◽  
Optimization Method ◽  
Relative Displacement ◽  
Form Solution ◽  
Jump Phenomenon ◽  
Nonlinear Parameters ◽  
Strongly Nonlinear ◽  
Damping Characteristics ◽  
Stiffness And Damping ◽  
Boundary Limits

In this paper using a modified averaging method the frequency response of a general nonlinear isolator is obtained. Stiffness and damping characteristics are considered cubic functions of displacement and velocity through the isolator. Analytical results are compared with those obtained by numerical integration in order to validate the closed form solution for strongly nonlinear isolator. While increasing the nonlinearity in the system improves the response of the isolator, stability and jump avoidance conditions set boundary limits for the parameters. The effects of nonlinear parameters to avoid jump phenomenon are discussed in detail. The set of parameters where the system behaves regularly are found and the nonlinear isolator is optimized based on RMS optimization method. Using this method the RMS function of absolute acceleration of the sprung mass is minimized versus the RMS function of relative displacement.

Calculation and Measurement of the Stiffness and Damping Coefficients for a Low Impedance Hydrodynamic Bearing

1997 ◽  
Vol 119 (1) ◽  
pp. 57-63 ◽  
Author(s):  
M. J. Goodwin ◽  
P. J. Ogrodnik ◽  
M. P. Roach ◽  
Y. Fang
Keyword(s):  
Experimental Data ◽  
Dynamic Stiffness ◽  
Perturbation Technique ◽  
The Novel ◽  
Oil Film ◽  
Hydrodynamic Bearing ◽  
Damping Coefficients ◽  
Stiffness And Damping ◽  
Film Stiffness ◽  
Novel Design

This paper describes a combined theoretical and experimental investigation of the eight oil film stiffness and damping coefficients for a novel low impedance hydrodynamic bearing. The novel design incorporates a recess in the bearing surface which is connected to a standard commercial gas bag accumulator; this arrangement reduces the oil film dynamic stiffness and leads to improved machine response and stability. A finite difference method was used to solve Reynolds equation and yield the pressure distribution in the bearing oil film. Integration of the pressure profile then enabled the fluid film forces to be evaluated. A perturbation technique was used to determine the dynamic pressure components, and hence to determine the eight oil film stiffness and damping coefficients. Experimental data was obtained from a laboratory test rig in which a test bearing, floating on a rotating shaft, was excited by a multi-frequency force signal. Measurements of the resulting relative movement between bearing and journal enabled the oil film coefficients to be measured. The results of the work show good agreement between theoretical and experimental data, and indicate that the oil film impedance of the novel design is considerably lower than that of a conventional bearing.

Sign in / Sign up

Export Citation Format

Share Document