Study of Dynamic Properties of Automotive Hydrobushing

2000 ◽  
Author(s):  
Min Lu ◽  
Judah Ari-Gur
Keyword(s):  
Mathematical Model ◽  
Resonant Frequency ◽  
Dynamic Properties ◽  
Dynamic Stiffness ◽  
Damping Ratio ◽  
Minimal Effect ◽  
Stiffness Ratio ◽  
Loss Angle ◽  
High Frequencies ◽  
Maximum Loss

Abstract The objective of this research is to understand the dynamic properties of the hydrobushing. By means of a proposed mathematical model, it is found that the dynamic stiffness and loss angle of a hydrobushing are related to the rubber property and the effectiveness of the fluid in the inertia track. At high frequencies, however, the fluid in the inertia track becomes inefficient so that it may be ignored. It is also concluded that the rubber damping has minimal effect on the hydrobushing dynamic properties and may be neglected. The maximum loss angle of a hydrobushing, which corresponds to the maximum damping coefficient, occurs at a frequency close to the fluid resonant frequency. The degree of its closeness depends on the damping ratio and dynamic stiffness ratio.

An Oscillating Disk Rheometer for Measuring Dynamic Properties during Vulcanization

1963 ◽  
Vol 36 (2) ◽  
pp. 451-458 ◽  
Author(s):  
G. E. Decker ◽  
R. W. Wise ◽  
D. Guerry
Keyword(s):  
Small Angle ◽  
High Frequency ◽  
Unique Feature ◽  
Dynamic Properties ◽  
Dynamic Stiffness ◽  
Low Frequency ◽  
Stress And Strain ◽  
Loss Angle ◽  
High Frequencies ◽  
Rubber Specimen

Abstract A forced oscillating-disk rheometer has been developed which can measure both the low and high frequency dynamic properties of a rubber specimen throughout vulcanization. It may also be used to measure the rheological properties of unvulcanized polymers. The instrument consists of a cone-shaped disk which is embedded in the rubber specimen and oscillated through a small angle while the specimen is heated under pressure. Both stress and strain in terms of torque and displacement, respectively, are measured by appropriate transducers and recorded on an oscillograph. Provisions are made for changing both frequency and strain. At low frequency, the instrument is a convenient tool for determining all of the curing parameters of a rubber specimen. At high frequencies, the change in the dynamic properties of a rubber specimen throughout vulcanization may be continuously followed. A unique feature of the rheometer is that the loss angle may be determined which permits resolution of the measured dynamic stiffness into its elastic and viscous components.

Study of Automotive Hydrobushing in Off-Axis Vibration

2001 ◽  
Author(s):  
Min Lu ◽  
Judah Ari-Gur ◽  
John Garety
Keyword(s):  
Resonant Frequency ◽  
Dynamic Behavior ◽  
Pressure Difference ◽  
Dynamic Stiffness ◽  
Fluid Pressure ◽  
Loss Angle ◽  
Static Stiffness ◽  
High Frequencies

Abstract A model was developed for the dynamic behavior of a misaligned hydrobushing, which is forced to oscillate in directions that are not aligned with the axis of the fluid chambers. It was found that the displacement of the fluid in the inertia track and of the equivalent piston peak at the fluid resonant frequency, but they decrease when the off-axis angle increases. Similarly, the fluid pressure difference between the chambers peaks at the fluid resonant frequency and it decreases when the off-axis angle increases. The dynamic stiffness and loss angle are functions of the off-axis angle and become less and less sensitive to the frequency when the off-axis angle increases. At high frequencies, the dynamic stiffness is the sum of the static stiffness and the equivalent volumetric stiffness. A comparison of the measured and calculated equivalent volumetric stiffness shows good correlation. But further work is needed to improve the accuracy of the dynamic stiffness and loss angle prediction.

Experimental Study on the Performance of the Laminated Steel Isolators

2013 ◽  
Vol 423-426 ◽  
pp. 1603-1607
Author(s):  
Yao Guo Xie ◽  
Ping He ◽  
Xian Qiang Qu ◽  
Hong Bin Cui
Keyword(s):  
Experimental Study ◽  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Damping Ratio ◽  
Dynamic Performance ◽  
Performance Testing ◽  
Stiffness Ratio ◽  
Static Stiffness ◽  
Comparison Of The Results

Through the analysis and comparison of the results of static and dynamic performance testing of a series of laminated steel pieces isolators used in the vibration isolation of warships, in the number and thickness of laminated steel pieces of the same circumstances, laminated steel arc and preload of test samples had a certain impact on the values ​​of static stiffness, dynamic stiffness, damping ratio as well as dynamic and static stiffness ratio.

scholarly journals Dynamic Properties of Pretreated Rubberized Concrete under Incremental Loading

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2183
Author(s):  
Aijiu Chen ◽  
Xiaoyan Han ◽  
Zhihao Wang ◽  
Tengteng Guo
Keyword(s):  
Stress Level ◽  
Dynamic Properties ◽  
Dynamic Stiffness ◽  
Damping Ratio ◽  
Rubberized Concrete ◽  
Rubber Content ◽  
Rubber Particles ◽  
Energy Dissipation Capacity ◽  
Stiffness And Damping ◽  
Incremental Loading

Recycling scrap tyres as alternative aggregates of concrete is an innovative option. To clarify the dynamic properties of the pretreated rubberized concrete with some cumulative damage, the natural frequency, flexural dynamic stiffness, and damping ratio of the specimens under incremental stress level were investigated in this paper. The results indicated that the pretreatment of rubber particles improved the strength, ductility, and crack resistance of the rubberized concrete. The reduction of the flexural dynamic stiffness was clarified with the increase of concrete stress level. The addition of the pretreated rubber particles enhanced the concrete energy dissipation capacity during the destruction, and the specimen dissipated more energy with the increase of rubber content before its failure.

Study on Dynamic Properties of Semi-Active Seism Isolator for Building

2012 ◽  
Vol 598 ◽  
pp. 299-302
Author(s):  
Wei Xiong Yu ◽  
Sheng Chun Yang
Keyword(s):  
Dynamic Properties ◽  
Dynamic Stiffness ◽  
Damping Ratio ◽  
Magnetorheological Elastomers

The dynamic properties of semi-active seism isolator for building made of magnetorheological elastomers (MRE) were studied. Semi-active seism isolators were designed with MRE, and their dynamic properties at different amplitudes, frequencies, preloads or currents were tested. The results show that the dynamic stiffness decreases with the increase of amplitude or preload, but increases with the rise of frequency or current; the damping ratio ascends with the increase of amplitude, but declines with the rise of preload.

scholarly journals Evaluation of Dynamic Properties of Sodium-Alginate-Reinforced Soil Using A Resonant-Column Test

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2743
Author(s):  
Seongnoh Ahn ◽  
Jae-Eun Ryou ◽  
Kwangkuk Ahn ◽  
Changho Lee ◽  
Jun-Dae Lee ◽  
...  
Keyword(s):  
Shear Modulus ◽  
Sodium Alginate ◽  
Shear Failure ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Reinforced Soil ◽  
Resonant Column ◽  
Column Test ◽  
Alginate Solution ◽  
Resonant Column Test

Ground reinforcement is a method used to reduce the damage caused by earthquakes. Usually, cement-based reinforcement methods are used because they are inexpensive and show excellent performance. Recently, however, reinforcement methods using eco-friendly materials have been proposed due to environmental issues. In this study, the cement reinforcement method and the biopolymer reinforcement method using sodium alginate were compared. The dynamic properties of the reinforced ground, including shear modulus and damping ratio, were measured through a resonant-column test. Also, the viscosity of sodium alginate solution, which is a non-Newtonian fluid, was also explored and found to increase with concentration. The maximum shear modulus and minimum damping ratio increased, and the linear range of the shear modulus curve decreased, when cement and sodium alginate solution were mixed. Addition of biopolymer showed similar reinforcing effect in a lesser amount of additive compared to the cement-reinforced ground, but the effect decreased above a certain viscosity because the biopolymer solution was not homogeneously distributed. This was examined through a shear-failure-mode test.

scholarly journals Identification of Dynamic Parameters of Pedestrian Walking Model Based on a Coupled Pedestrian–Structure System

2021 ◽  
Vol 11 (14) ◽  
pp. 6407
Author(s):  
Huiqi Liang ◽  
Wenbo Xie ◽  
Peizi Wei ◽  
Dehao Ai ◽  
Zhiqiang Zhang
Keyword(s):  
Negative Correlation ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Field Testing ◽  
The Body ◽  
Structural Vibration ◽  
Pedestrian Dynamics ◽  
Structure Interaction ◽  
Mass Spring ◽  
Stiffness And Damping

As human occupancy has an enormous effect on the dynamics of light, flexible, large-span, low-damping structures, which are sensitive to human-induced vibrations, it is essential to investigate the effects of pedestrian–structure interaction. The single-degree-of-freedom (SDOF) mass–spring–damping (MSD) model, the simplest dynamical model that considers how pedestrian mass, stiffness and damping impact the dynamic properties of structures, is widely used in civil engineering. With field testing methods and the SDOF MSD model, this study obtained pedestrian dynamics parameters from measured data of the properties of both empty structures and structures with pedestrian occupancy. The parameters identification procedure involved individuals at four walking frequencies. Body frequency is positively correlated to the walking frequency, while a negative correlation is observed between the body damping ratio and the walking frequency. The test results further show a negative correlation between the pedestrian’s frequency and his/her weight, but no significant correlation exists between one’s damping ratio and weight. The findings provide a reference for structural vibration serviceability assessments that would consider pedestrian–structure interaction effects.

scholarly journals Multi-Scale Study of The Small-Strain Damping Ratio of Fiber-Sand Composites

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2476
Author(s):  
Haiwen Li ◽  
Sathwik S. Kasyap ◽  
Kostas Senetakis
Keyword(s):  
Dynamic Properties ◽  
Wide Spectrum ◽  
Damping Ratio ◽  
Polypropylene Fiber ◽  
Small Strain ◽  
Treatment Method ◽  
Fiber Content ◽  
Polypropylene Fibers ◽  
Test Results ◽  
Fiber Reinforced

The use of polypropylene fibers as a geosynthetic in infrastructures is a promising ground treatment method with applications in the enhancement of the bearing capacity of foundations, slope rehabilitation, strengthening of backfills, as well as the improvement of the seismic behavior of geo-systems. Despite the large number of studies published in the literature investigating the properties of fiber-reinforced soils, less attention has been given in the evaluation of the dynamic properties of these composites, especially in examining damping characteristics and the influence of fiber inclusion and content. In the present study, the effect of polypropylene fiber inclusion on the small-strain damping ratio of sands with different gradations and various particle shapes was investigated through resonant column (macroscopic) experiments. The macroscopic test results suggested that the damping ratio of the mixtures tended to increase with increasing fiber content. Accordingly, a new expression was proposed which considers the influence of fiber content in the estimation of the small-strain damping of polypropylene fiber-sand mixtures and it can be complementary of damping modeling from small-to-medium strains based on previously developed expressions in the regime of medium strains. Additional insights were attempted to be obtained on the energy dissipation and contribution of fibers of these composite materials by performing grain-scale tests which further supported the macroscopic experimental test results. It was also attempted to interpret, based on the grain-scale tests results, the influence of fiber inclusion in a wide spectrum of properties for fiber-reinforced sands providing some general inferences on the contribution of polypropylene fibers on the constitutive behavior of granular materials.

scholarly journals Nominal and Actual Values of Inductor and Capacitor Parameters at High Frequencies

2019 ◽  
Vol 7 (4) ◽  
pp. 44-53 ◽  
Author(s):  
E. V. Gurov ◽  
S. S. Uvaysov ◽  
A. S. Uvaysova ◽  
S. S. Uvaysova
Keyword(s):  
Resonant Frequency ◽  
High Frequency ◽  
The Self ◽  
Impedance Match ◽  
Analog Filters ◽  
Reactive Component ◽  
High Frequencies ◽  
Coil Inductance ◽  
Parasitic Parameters ◽  
Capacitor Capacitance

Coil inductance and capacitor capacitance depend on overall dimensions, structure, and ambient factors. They do not vary with frequency. Reactive component impedance is determined by inductance or capacitance respectively, if active resistance is not considered. This is true for the frequencies which are significantly lower than the self-resonant frequency of the component. Parasitic parameters contribution increases on approaching the self-resonant frequency. Therefore, the componentʼs actual inductance and actual capacitance on operating frequency are defined. They are provided by manufacturers and differ from the nominal values. The actual values provide more accurate impedance of components near the considered frequency. Significant deviation from the considered frequency can cause impedance mismatch even more than the nominal values can provide. Frequency response of the high-frequency circuits such as analog filters and impedance match networks are determined by components impedance, not the nominal values. Thus, calculated values must be close to the actual values. The purpose of this article is to justify actual values application instead of nominal values.

scholarly journals Effect of Grain Refinement on the Dynamic, Mechanical Properties, and Corrosion Behaviour of Al-Mg Alloy

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1825
Author(s):  
Haitham M. Ahmed ◽  
Hussin A. M. Ahmed ◽  
Mohammed Hefni ◽  
Essam B. Moustafa
Keyword(s):  
Mechanical Properties ◽  
Grain Refinement ◽  
Corrosion Behaviour ◽  
Cast Alloy ◽  
Dynamic Properties ◽  
Damping Ratio ◽  
Xrd Analysis ◽  
Optical Microscope ◽  
Mg Alloy ◽  
Resonance Frequencies

In this investigation, aluminium Al-2.5% Mg cast alloy was modified by adding 0.5 Ti and 0.1 B wt % modifiers to investigate their impact on the dynamic behaviour, as well as the mechanical and microstructure properties. The dynamic properties were analysed experimentally using a free vibration impact test and predicted using finite element methods. This study used a high-resolution polarised optical microscope to analyse the microstructure of the studied alloys and X-ray Powder Diffraction (XRD) analysis to determine the developed phases. Microstructure and mechanical properties were mostly enhanced as a result of grain refining during solidification and through the metal segregation process. The microstructure analysis of the modified alloy showed a significant improvement in the grain refinement; hence, the grains were 10 times finer than the cast alloy. The modified Al-2.5% Mg/Ti-B alloy demonstrated reduced inter-granular corrosion (IGC) than the Al-2.5% Mg standard cast alloy. By incorporating Ti-B modifiers into the composition of the cast Al-Mg alloy, the ultimate tensile strength (UTS), strain (ε), and hardness values (HV) were increased by 30.5%, 100%, and 18.18%, respectively. The dynamic properties of the modified alloy showed an enhancement in the resonant (fn) and damping ratio (ζ) by 7% and 68%, respectively. The predicted resonance frequencies of the investigated alloys showed results close to the experimental dynamic tests.

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