Tests and Modeling of a New Vibration Isolation and Suppression Device

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
Zhao-Dong Xu ◽  
Yeshou Xu ◽  
Qianqiu Yang ◽  
Chao Xu ◽  
Feihong Xu ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Energy Dissipation ◽  
Viscoelastic Material ◽  
Vibration Isolation ◽  
Dynamic Properties ◽  
Excitation Frequency ◽  
Dynamic Responses ◽  
Damping Capacity ◽  
Air Spring ◽  
Energy Dissipation Devices

Vibration is an environmental factor with hazardous effects on the instruments' precision, structural stability, and service life in engineering fields. Many kinds of energy dissipation devices have been invented to reduce the dynamic responses of structures and instruments due to environmental excitations. In this paper, a new kind of vibration isolation and suppression device with high damping performance, fine deformation recoverability, and bearing capacity for platform structures is developed, which is designed by considering the combination of the energy dissipation mechanisms of viscoelastic material, viscous fluid, and air spring. A series of dynamic properties tests on the device are carried out under different excitation frequencies and displacement amplitudes, and a mathematical model considering the coupling effects of energy dissipation of viscoelastic material, viscous liquid, and air spring is proposed. The research results indicate that the vibration isolation and suppression device has high damping capacity, and the proposed mathematical model can well describe the mechanical properties affected by excitation frequency and displacement amplitude.

Modeling and analysis of a viscoelastic micro-vibration isolation and mitigation platform for spacecraft

2017 ◽  
Vol 24 (18) ◽  
pp. 4337-4352 ◽  
Author(s):  
Chao Xu ◽  
Zhao-Dong Xu ◽  
Xing-Huai Huang ◽  
Ye-Shou Xu ◽  
Teng Ge
Keyword(s):  
Energy Dissipation ◽  
Analytical Model ◽  
Viscoelastic Material ◽  
Vibration Isolation ◽  
Dynamic Properties ◽  
Coupled System ◽  
Mathematic Model ◽  
Experimental Results ◽  
Modeling And Analysis ◽  
Micro Vibration

A new viscoelastic micro-vibration isolation and mitigation platform is proposed to reduce disturbances generated by flywheels on board spacecraft. Firstly, property tests on the high-damping viscoelastic material used in the micro-vibration isolation and mitigation element are conducted. Experimental results show that the developed viscoelastic material has better energy dissipation capability under micro-vibration conditions. A mathematic model is employed to describe the dynamic properties of the high-damping viscoelastic material and is used to model the isolation and mitigation element. Secondly, a viscoelastic micro-vibration isolation and mitigation platform, which consists of four elements, is proposed and the analytical model of the coupled system that consists of the platform with flywheel is established. Finally, the isolation and mitigation performances of this micro-vibration isolation and mitigation platform are analyzed and discussed. The results show that the isolation and mitigation platform can effectively reduce the micro-vibration disturbances induced by the flywheel.

scholarly journals Effect of Preservation Period on the Viscoelastic Material Properties of Soft Tissues With Implications for Liver Transplantation

2010 ◽  
Vol 132 (10) ◽  
Author(s):  
Sina Ocal ◽  
M. Umut Ozcan ◽  
Ipek Basdogan ◽  
Cagatay Basdogan
Keyword(s):  
Liver Transplantation ◽  
Viscoelastic Material ◽  
Material Properties ◽  
Soft Tissues ◽  
Excitation Frequency ◽  
Viscoelastic Model ◽  
Relaxation Modulus ◽  
Bovine Liver ◽  
Dynamic Responses ◽  
Time Dependent

The liver harvested from a donor must be preserved and transported to a suitable recipient immediately for a successful liver transplantation. In this process, the preservation period is the most critical, since it is the longest and most tissue damage occurs during this period due to the reduced blood supply to the harvested liver and the change in its temperature. We investigate the effect of preservation period on the dynamic material properties of bovine liver using a viscoelastic model derived from both impact and ramp and hold experiments. First, we measure the storage and loss moduli of bovine liver as a function of excitation frequency using an impact hammer. Second, its time-dependent relaxation modulus is measured separately through ramp and hold experiments performed by a compression device. Third, a Maxwell solid model that successfully imitates the frequency- and time-dependent dynamic responses of bovine liver is developed to estimate the optimum viscoelastic material coefficients by minimizing the error between the experimental data and the corresponding values generated by the model. Finally, the variation in the viscoelastic material coefficients of bovine liver are investigated as a function of preservation period for the liver samples tested 1 h, 2 h, 4 h, 8 h, 12 h, 24 h, 36 h, and 48 h after harvesting. The results of our experiments performed with three animals show that the liver tissue becomes stiffer and more viscous as it spends more time in the preservation cycle.

scholarly journals Editorial for Special Issue “Energy Dissipation and Vibration Control: Materials, Modeling, Algorithm, and Devices”

2020 ◽  
Vol 10 (2) ◽  
pp. 572 ◽  
Author(s):  
Gangbing Song ◽  
Hong-Nan Li ◽  
Steve C.S. Cai
Keyword(s):  
Energy Dissipation ◽  
Vibration Control ◽  
Active Vibration Control ◽  
Vibration Damping ◽  
Dynamic Responses ◽  
Special Issue ◽  
The Arts ◽  
Materials Modeling ◽  
Active Vibration ◽  
Energy Dissipation Devices

Many engineering systems, from subsea pipelines to space structures, from moving vehicles to stationary skyscrapers, are subject to unwanted vibration excitations. Often vibration control can be considered as a problem of energy dissipation and vibration damping. The aims of this issue are to accumulate, disseminate, and promote new knowledge about vibration control, especially for topics related to energy dissipation methods for vibration damping. Topics in this issue reflect the start-of-the-arts in the field of vibration control, such as inerter dampers and pounding tuned mass dampers (PTMDs). This special issue also reports other types of new energy dissipation devices, including a multi-unit particle damper, a nonlinear eddy current damper, and layered dampers. Also reported in this issue are structural elements with innovative designs to dissipate energy. In addition, this special issue also reports two research studies on the dynamic responses of a structural foundation and an earth-retaining structure. Though most papers in this special issue are related to passive methods, one paper reports a semi-active vibration control via magnetorheological dampers (MRDs), and another two papers report active vibration controls using piezoelectric transducers and inertial actuators, respectively.

Analysis and Experiment of an Air Vibration Isolation System with Auxiliary Chambers

2012 ◽  
Vol 226-228 ◽  
pp. 195-198
Author(s):  
Rong Wei Wen ◽  
Jiu Bin Tan ◽  
Lei Wang ◽  
Guan Hua Wang
Keyword(s):  
Resonant Frequency ◽  
Vibration Isolation ◽  
Excitation Frequency ◽  
Volume Ratio ◽  
Air Spring ◽  
Working Pressure ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Vibration Transmissibility ◽  
System Vibration

A mathematical model of a single degree of freedom air spring vibration isolation system is established. The model analyzes the influence of structural damping in the air spring vibration isolation system based on the traditional model. This paper establishes the relationship between the working pressure p, the volume ratio of n and system vibration transmissibility T under forced vibration. The experimental results are verified on different working pressure. The results showed that working pressure p has little effect on the resonant frequency of the system and the system vibration transmissibility. The smaller the ratio n, the lower the resonant frequency of the system and the system vibration transmissibility. The environmental excitation frequency range must be taken into account in designing.

scholarly journals Dynamic Properties and Energy Dissipation Study of Sandwich Viscoelastic Damper Considering Temperature Influence

Buildings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 470
Author(s):  
Yeshou Xu ◽  
Zhaodong Xu ◽  
Yingqing Guo ◽  
Xinghuai Huang ◽  
Yaorong Dong ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Dynamic Properties ◽  
Excitation Frequency ◽  
Viscoelastic Damper ◽  
Kelvin Model ◽  
Viscoelastic Dampers ◽  
Self Heating ◽  
Passive Energy Dissipation ◽  
Sandwich Type ◽  
Environmental Temperatures

Viscoelastic dampers are a kind of classical passive energy dissipation and vibration control devices which are widely utilized in engineering fields. The mechanical properties and energy dissipation capacity of the viscoelastic damper are significantly affected by ambient temperature. In this work, dynamic properties tests of the sandwich type viscoelastic damper at different environmental temperatures are carried out. The equivalent fractional Kelvin model which can characterize the mechanical behavior of the viscoelastic damper with varying frequencies and temperatures is introduced to describe the dynamic properties and energy dissipation capability of the sandwich viscoelastic damper. The self-heating phenomenon of the sandwich viscoelastic damper is studied with a numerical simulation, and the dynamic properties and energy dissipation variation of the viscoelastic damper with self-heating processes are also analyzed. The results show that the dynamic properties of the viscoelastic damper are significantly affected by temperature, excitation frequency and the internal self-generated heating.

Theoretical and Experimental Analysis of the Non-Linear Characteristics of an Air Spring With an Orifice

2011 ◽  
Author(s):  
Yasutaka Yokota ◽  
Toshihiko Asami ◽  
Tomohiko Ise ◽  
Itsuro Honda ◽  
Hiroya Sakamoto
Keyword(s):  
Vibration Isolation ◽  
Dynamic Properties ◽  
Flow Characteristics ◽  
Accurate Method ◽  
Air Spring ◽  
Damping Force ◽  
Linear Flow ◽  
Iterative Calculation ◽  
Non Linear ◽  
Amplitude Dependency

This paper proposes a simple but accurate method for calculating the dynamic properties of an air spring employing an orifice to produce a damping force. Air springs are very common in rail, automotive, and vibration isolation applications. However, because this type of air spring has non-linear flow characteristics, an accurate model is yet to be proposed. The restoring and damping forces in an air spring with an orifice damper vary with amplitude. This amplitude dependency has not been considered in previous studies. Proposed herein is a simple model for calculating the air spring constant and damping coefficient. However, iterative calculation is required due to the non-linearity of the spring. The theoretical and experimental results are found to agree well. The theoretical equations provide an effective tool for air spring design.

Theoretical and Experimental Analysis of the Nonlinear Characteristics of an Air Spring With an Orifice

2013 ◽  
Vol 135 (1) ◽  
Author(s):  
Toshihiko Asami ◽  
Yasutaka Yokota ◽  
Tomohiko Ise ◽  
Itsuro Honda ◽  
Hiroya Sakamoto
Keyword(s):  
Vibration Isolation ◽  
Dynamic Properties ◽  
Flow Characteristics ◽  
Accurate Method ◽  
The Body ◽  
Nonlinear Flow ◽  
Air Spring ◽  
Damping Force ◽  
Nonlinear Characteristics ◽  
Amplitude Dependency

We herein propose a simple but accurate method for calculating the dynamic properties of an air spring that uses an orifice to produce a damping force. Air springs are commonly used in rail, automotive, and vibration isolation applications. However, because this type of air spring has nonlinear flow characteristics, accurate approaches have not yet been proposed. The restoring and damping forces in an air spring with an orifice damper vary with the amplitude of the body. This amplitude dependency has not been considered in previous studies. We herein propose a simple model for calculating the air spring constant and damping coefficient. However, this requires iterative calculation due to the nonlinearity of the air spring. The theoretical and experimental results are found to agree well with each other. The theoretical equations provide an effective tool for air spring design.

Attitude Control of Air Spring Mounting System Based on Fuzzy Control

2007 ◽  
Author(s):  
Wenjun Bu ◽  
Lin He ◽  
Shujun Shan
Keyword(s):  
Control Strategy ◽  
Attitude Control ◽  
Vibration Isolation ◽  
Dynamic Properties ◽  
Engineering Application ◽  
Air Spring ◽  
Object A ◽  
Constant Change ◽  
Environment Temperature ◽  
Coupling Characteristic

Air spring is a kind of mount with excellent vibration isolation effect and it uses air as its elastic component. But its height is subject to constant change due to air leak or environment temperature and this restricts its engineering application. So some studies on attitude control are carried out, focusing on statically indeterminate and multivariable coupling air spring mounting systems in this paper. The Statically indeterminate problem is transformed through adding the constraint of loading evenness among air springs. After analyzing the model of this controlled object, a new control strategy based on coupling characteristic recognition is presented and combined with fuzzy logic control to realize attitude control of the multivariable coupling system. Finally, a test is conducted to show that the control strategy is feasible and the control system has good static and dynamic properties.

scholarly journals Viscoelastic Material as Energy Dissipater Viscoelastic Damper for Building Structures to Mitigate the Seismic Vibration

2019 ◽  
Vol 29 (2) ◽  
pp. 41-49
Author(s):  
Waseem Sarwar
Keyword(s):  
Viscoelastic Material ◽  
Performance Index ◽  
Dynamic Properties ◽  
Loss Modulus ◽  
Excitation Frequency ◽  
Structural Response ◽  
Mechanical Analysis ◽  
Building Structures ◽  
Seismic Vibration ◽  
Viscoelastic Dampers

Abstract The supplemental energy dissipation system is a practical approach to attenuate the structural response under extreme loading. Viscoelastic damping used to reinforce the structure against the seismic vibration, Viscoelastic material (VEM) most commonly used in viscoelastic dampers (VEDs). In this paper, dynamic mechanical analysis (DMA) approach is used to investigate the performance index of VEM. It is demonstrated that the performance index, such as storage modulus, loss modulus, and loss factor decrease noticeably as the temperature increases, which reflects the low stiffness at high temperature. Excitation frequency also influenced the performance index, and the reaction has correspondence to temperature. As the temperature increases, the VEM dynamic properties decreases, which represents the rubbery region, and it is found that higher to low-temperature dynamic properties increases, which the glassy region is. DMA is a particularly flexible approach, and it characterizes the properties of VEM simultaneously at various conditions.

Low-Cycle Fatigue Performance of Buckling Restrained Braces and Assessment of Cumulative Damage under Severe Earthquakes

2018 ◽  
Vol 763 ◽  
pp. 867-874
Author(s):  
Yu Shu Liu ◽  
Ke Peng Chen ◽  
Guo Qiang Li ◽  
Fei Fei Sun
Keyword(s):  
Fatigue Life ◽  
Energy Dissipation ◽  
Structural Reliability ◽  
Low Cycle Fatigue ◽  
Engineering Application ◽  
Fatigue Performance ◽  
Cycle Fatigue ◽  
Variable Amplitude ◽  
Buckling Restrained Braces ◽  
Energy Dissipation Devices

Buckling Restrained Braces (BRBs) are effective energy dissipation devices. The key advantages of BRB are its comparable tensile and compressive behavior and stable energy dissipation capacity. In this paper, low-cycle fatigue performance of domestic BRBs is obtained based on collected experimental data under constant and variable amplitude loadings. The results show that the relationship between fatigue life and strain amplitude satisfies the Mason-Coffin equation. By adopting theory of structural reliability, this paper presents several allowable fatigue life curves with different confidential levels. Besides, Palmgren-Miner method was used for calculating BRB cumulative damages. An allowable damage factor with 95% confidential level is put forward for assessing damage under variable amplitude fatigue. In addition, this paper presents an empirical criterion with rain flow algorithm, which may be used to predict the fracture of BRBs under severe earthquakes and provide theory and method for their engineering application. Finally, the conclusions of the paper were vilified through precise yet conservative prediction of the fatigue failure of BRB.

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