Influence of Fractional Damping and Time Delay on Maxwell-Voigt Model for Vibration Isolation

2016 ◽  
Author(s):  
Sudhir Kaul
Keyword(s):  
Time Delay ◽  
Dynamic Characteristics ◽  
Vibration Isolation ◽  
Model Parameters ◽  
Fractional Damping ◽  
Vibration Isolators ◽  
Multiple Parameters ◽  
Realistic Representation ◽  
Voigt Model ◽  
Isolation Systems

Models of vibration isolators are very commonly used for the design and analysis of isolation systems. Accurate isolator modeling is critical for a successful prediction of the dynamic characteristics of isolated systems. Isolators exhibit a complex behavior that depends on multiple parameters such as frequency, displacement amplitude, temperature and loading conditions. Therefore, it is important to choose a model that is accurate while adequately representing the relationships with relevant parameters. Recent literature has indicated some inherent advantages of fractional derivatives that can be exploited in the modeling of elastomeric isolators. Furthermore, time delay of damping is also seen to provide a realistic representation of damping. This paper examines the Maxwell-Voigt model with fractional damping and a time delay. This model is compared with the conventional Maxwell-Voigt model (without time delay or fractional damping) and the Voigt model in order to comprehend the influence of fractional damping and time delay on dynamic characteristics. Multiple simulations are performed after identifying model parameters from the data collected for a passive elastomeric isolator. The analysis results are compared and it is observed that the Voigt model is highly sensitive to fractional damping as well as time delay.

Maxwell-Voigt and Voigt Models for Vibration Isolation: Influence of Fractional Damping and Time Delay

2018 ◽  
Author(s):  
Sudhir Kaul
Keyword(s):  
Time Delay ◽  
Frequency Response ◽  
Fractional Order ◽  
Vibration Isolation ◽  
Damping Ratio ◽  
Maximum Amplitude ◽  
Damping Force ◽  
Fractional Damping ◽  
Integer Order ◽  
Voigt Model

This paper presents results from a follow-up study of fractional damping and time delay. Fractional damping has been used in the literature to demonstrate certain advantages over integer-order damping in many applications involving viscoelastic characteristics. It is observed that fractional damping can be used to influence stability boundaries, natural frequencies and vibration amplitudes, thus providing modeling flexibility in predicting the response of an isolated system during preliminary design. Additionally, time delay or lag is known to be inherent in a damped system, therefore a direct representation of time delay in modeling the damping force is expected to enhance model fidelity. This paper investigates the use of Voigt and Maxwell-Voigt models that incorporate fractional damping and time delay. In this paper, fractional damping has been particularly introduced to investigate possible improvements in the frequency response. Results indicate that fractional damping can be used to significantly enhance the capability of the Voigt model. The influence of the fractional order is found to be analogous to the damping ratio in an integer-order model. Fractional order is seen to exhibit a somewhat limited influence on the Maxwell-Voigt model. However, attributes such as the peak frequency and maximum amplitude are seen to be directly influenced by the fractional order. Although time delay is seen to exhibit an influence on the frequency response, it needs to be limited within useful bounds. Overall, it is observed that fractional order and time delay can be used to improve the accuracy of the Voigt and Maxwell-Voigt models. These enhanced models can be used for the design and development of elastomeric isolators and vibration isolation systems.

scholarly journals The Effect of Fractional Damping and Time-delayed Feedback on the Stochastic Resonance of Asymmetric SD Oscillator

2021 ◽  
Author(s):  
Qiubao Wang ◽  
Hao Wu ◽  
Yuejuan Yang
Keyword(s):  
Time Delay ◽  
Stochastic Resonance ◽  
Vibration Isolation ◽  
Weak Signal Detection ◽  
Fractional Damping ◽  
System Parameters ◽  
Sd Oscillator ◽  
Delay Feedback Control ◽  
Detection Energy ◽  
Time Delayed Feedback

Abstract This paper proposes the stiffness nonlinearities and asymmetric SD (smooth and discontinuous) oscillators under time-delay feedback control with a fractional damping. With the effect of displacement and velocity feedback, the oscillator is adjusted to the desired vibration state and then the stochastic resonance (SR) is achieved. This article discusses the contribution of various system parameters and time-delay feedback to SR, especially which induced by fractional damping. It should be noted that this paper provides effective guidance for fault diagnosis and weak signal detection, energy harvesting, vibration isolation and vibration reduction.

scholarly journals Influence of the use of spring vibration isolators in the construction of track pavement for damping vibrations from the track

2018 ◽  
Vol 2018 (5) ◽  
pp. 1-9
Author(s):  
Ewelina Kwiatkowska ◽  
Wiesław Fiebig
Keyword(s):  
Noise Reduction ◽  
Vibration Isolation ◽  
New Technology ◽  
Track Structure ◽  
Vibration Isolators ◽  
Isolation Systems ◽  
Tuning Frequency ◽  
Mass Spring ◽  
Lower Frequencies

The paper presents tuned track bed vibration isolation systems used for the railway and tramway lines. The presented solution based on mass spring systems and is effective especially at lower frequencies. The tuning frequency of such systems is mostly in the range 5 to 8 Hz. With measures based on spring elements elaborated by GERB company the significant vibration and noise reduction coming from the railways and tramways can be achieved. This new technology in Poland can be used during the track structure modernization as well as in the new projects, in which the track bed vibration isolation is required.

scholarly journals Vibration Isolation Critical to Measuring Neuronal Patterns in the Brain

2009 ◽  
Vol 17 (3) ◽  
pp. 12-15
Author(s):  
David L. Platus
Keyword(s):  
Neuronal Activity ◽  
Vibration Isolation ◽  
Medical Center ◽  
Low Frequency ◽  
Vibration Isolators ◽  
Low Frequency Vibration ◽  
Conducting Research ◽  
Neuronal Patterns ◽  
Isolation Systems ◽  
The Brain

Researchers at Georgetown University's Department of Physiology and Biophysics use negative-stiffness vibration isolators to help measure micron-level patterns of neuronal activity in the mammalian neocortex. The research is shedding new light into brain sensory and motor processing functions relating to cardiac fibrillation and epilepsy.Isolating a laboratory's sensitive microscopy equipment against low-frequency vibration has become increasingly more vital to maintaining imaging quality and data integrity for neurobiology researches. Ever more frequently, laboratory researchers are discovering that conventional air tables and the more recent active (electronic) vibration isolation systems are not able to adequately cancel out the lower frequency perturbations derived from air conditioning systems, outside vehicular movements and ambulatory personnel. Such was the case with the Department of Physiology and Biophysics at Georgetown University Medical Center, where Professor Jian-Young Wu has been conducting research on waves of neuronal activity in the neocortex of the brain.

scholarly journals INCREASED VIBRATION ON REFRIGERATOR SHIPS OF B437/11 PROJECT AND TECHNICAL PROPOSALS ON ITS REDUCTION

2018 ◽  
pp. 58-69
Author(s):  
Minas Armenakovich Minasyan ◽  
Aung Myo Thant ◽  
Armen Minasovich Minasyan
Keyword(s):  
Service Life ◽  
Vibration Isolation ◽  
Steel Wire ◽  
Modern Technology ◽  
Wire Rope ◽  
Diesel Generator ◽  
Vibration Isolators ◽  
Wide Range ◽  
Isolation Systems ◽  
The Impact

The paper considers the causes of increased vibration of four auxiliary diesel-generator sets of "Sulzer" 5АL25 type on board nine refrigerated vessels of B437 / 11 project after 15 years of operation. The proposed wide range of possible applications to address the problem of high vibration of diesel generators and motor vessels there were generally implemented upgraded turbocharger brackets, engine sub-frame and supporting spiral-rope vibration isolators in the shock absorption system of the diesel-generator. Four original patented technical solutions have been presented, among which one solution is implemented in 5AL25 diesel generator and 2H 8.5/11 diesel damping systems. There has been offered wide application both wire rope vibration isolators and combined isolators, in which elastic elements are made of nonflammable materials. Wire rope vibration isolators combine high bearing capacity (static loads within 1 N - 50 kN) with high elasticity under dynamic effects; their natural frequencies can drop to 2.5 Hz. Under the worst conditions 75% of the free moving weakens the impact to values that ensure the necessary safety of the object. Experience in designing vibration isolation systems allows to set the maximum range of loads within 15 - 25 g. The vibration isolators made of steel wire rope are practically not affected by the environment, they are made of stainless steel. They effectively operate at temperatures -200°C - +370°C in the presence of oil, dirt, sand, salt fog, etc. They usually have a service life comparable with the service life of the insulated object. Wire rope vibration isolators and combined vibration isolators can be used in all fields of modern technology: shipbuilding, power engineering, automotive, aviation and space industries, etc.

Nonlinear Design of a Passive Vibration Isolator: Influence of Multi-Axial Stiffness

2019 ◽  
Author(s):  
Sudhir Kaul
Keyword(s):  
Dynamic Response ◽  
Dynamic Stiffness ◽  
Harmonic Balance Method ◽  
Axial Stiffness ◽  
Vibration Isolators ◽  
Trade Offs ◽  
Nonlinear Design ◽  
Integration Test ◽  
Voigt Model ◽  
Isolation Systems

Abstract Passive vibration isolators are widely used in multiple engineering applications to reduce resonance peaks or to mitigate transmissibility in the presence of internal or external sources of dynamic excitation. The design of a linear passive isolator involves multiple trade-offs. In the literature, different design configurations with nonlinearities have been investigated to limit some of these trade-offs. These include designs with quasi-zero stiffness (QZS) or high-static-low-dynamic stiffness (HSLDS) characteristics. This study investigates three viscoelastic models that incorporate stiffness nonlinearity along the non-isolating axes in order to exhibit more control over the dynamic response of the isolated system and possibly mitigate some of the design trade-offs. The dynamic response of these three models is compared to an existing HSLDS model in the literature. The three models investigated in this study are as follows: Kelvin-Voigt (or Voigt), Zener, and Generalized Maxwell (or Maxwell Ladder). These three models have been commonly used in the literature for vibration analysis of passive isolators. Two methods have been used for analysis, namely the Harmonic Balance Method (HBM) and explicit numerical integration. Test results from a previous study have been used for model characterization of all the models. It is observed that the modified Kelvin-Voigt model is analogous to the HSLDS model from the literature. For the isolator parameters used in this study, it is observed that the Kelvin-Voigt model with stiffness nonlinearity is able to exhibit characteristics similar to the HSLDS design, this includes the jump phenomenon as well as the hardening behavior. In general, all three models demonstrate that stiffness nonlinearity results in a reduction in peak transmissibility as well as an enhancement of the isolation bandwidth. The findings of this study could be useful in the design of passive isolation systems for products with significantly different multi-axial requirements with various design constraints.

scholarly journals A Novel Approach to the Analysis of Under Sleeper Pads (USP) Applied in the Ballasted Track Structures

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2438 ◽  
Author(s):  
Artur Zbiciak ◽  
Cezary Kraśkiewicz ◽  
Anna Al Sabouni-Zawadzka ◽  
Jan Pełczyński ◽  
Sławomir Dudziak
Keyword(s):  
Finite Element ◽  
Dynamic Characteristics ◽  
Mechanical Model ◽  
Rheological Model ◽  
Laboratory Tests ◽  
Vibration Isolation ◽  
Special Focus ◽  
Vibration Isolators ◽  
Novel Approach ◽  
Ballasted Track

The present paper is dedicated to the analysis of under sleeper pads (USP), which are resilient elements used in ballasted track systems as vibration isolators. Four types of USP are considered. The authors present the results of laboratory tests, which are then used as input values for the finite element (FE) and mechanical model of the structure. A special focus is put on the description of an original four-degree-of-freedom (4DoF) mechanical model of the system that includes a fractional rheological model of USP. Using the proposed approaches, the dynamic characteristics of under sleeper pads are determined, and conclusions on vibration isolation effectiveness are drawn.

Semi-Active Isolators Using Electrorheological/Magnetorheological Fluids

2002 ◽  
Vol 33 (11) ◽  
pp. 16-19
Author(s):  
Young-Tai Choi ◽  
Norman M. Wereley ◽  
Young-Sik Jeon
Keyword(s):  
Vibration Isolation ◽  
Colloidal Suspensions ◽  
Fast Response ◽  
Magnetorheological Fluids ◽  
External Signal ◽  
Continuous Control ◽  
Vibration Isolators ◽  
Mr Fluids ◽  
Research Activities ◽  
Isolation Systems

ER (electrorheological)/MR (magnetorheological) fluids are colloidal suspensions that can control their rheological properties such as viscosity and yield stress in response to external signal. As a result, applications using ER/MR fluids have useful features such as fast response time and continuous control ability. These kinds of inherent advantages of ER/MR fluids trigger a lot of research activities on ER/MR applications including controllable vibration isolation systems, torque-transmission devices, and others. Among them, semi-active ER/MR fluid-based vibration isolators will be studied in this paper. The semi-active isolators can effectively isolate systems from various external disturbances with low power consumption, so that the system should not expose to significant dynamic stress and fatigue damage.

scholarly journals Line Spectrum Chaotification on QZS Systems with Time-Delay Control

Complexity ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Jing Zhang ◽  
Tao Tang ◽  
Wenhua Fang
Keyword(s):  
Comparative Analysis ◽  
Time Delay ◽  
Numerical Simulations ◽  
Vibration Isolation ◽  
Line Spectrum ◽  
New Approach ◽  
Time Delay Control ◽  
Control Gain ◽  
Delay Control ◽  
Isolation Systems

Chaotification can be employed to weaken or eliminate the feature of line spectra of waterborne noise. The efficiency of this method lies on the use of small control. The analysis reveals that the critical control gain depends on the stiffness of vibration isolation systems. Thus, an isolation raft system based on quasi-zero-stiffness (QZS) property is proposed for line spectrum chaotification. A nonlinear time-delay controller is derived accordingly. Comparative analysis shows that the new approach allows much smaller control, and the intensity of line spectra is further reduced. Numerical simulations also indicate other advantages with the introduction of QZS system into chaotification.

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