scholarly journals The nonlinear vibrations of a vertical hard gyroscopic rotor with nonlinear characteristics

2019 ◽  
Vol 10 (2) ◽  
pp. 529-544 ◽  
Author(s):  
Zharilkassin Iskakov ◽  
Kuatbay Bissembayev
Keyword(s):  
High Velocity ◽  
Nonlinear Vibrations ◽  
Rotational Velocity ◽  
Nonlinear Damping ◽  
Nonlinear Characteristics ◽  
Vibration Isolators ◽  
Absolute Displacement ◽  
Linear Damping ◽  
Force Transmissibility ◽  
The Moment

Abstract. The paper considers an impact of viscous linear and cubic nonlinear damping of the elastic support on nonlinear vibrations of a vertical hard gyroscopic unbalanced rotor, taking into account nonlinear stiffness of the support material. Analyzing the research results shows that linear and cubic nonlinear damping can significantly suppress the resonance peak of the fundamental harmonic, eliminate the jumping phenomena of the nonlinear system. In non-resonance areas where the velocity is higher than the critical one, cubic nonlinear damping, unlike linear one, can slightly suppress amplitude of the rotor vibration. Therefore, in the high-velocity area, only nonlinear damping can maintain performance of a vibration isolator. In resonance area, an increase in linear or cubic nonlinear damping significantly suppresses the ability to absolute displacement. In non-resonance area, where the rotational velocity is lower than the critical one, they have almost no impact on ability to absolute displacement. In high velocity area, an increase in nonlinear damping may slightly increase the moment of force transmissibility, but linear damping has almost no impact on it. The obtained results can be successfully used to produce passive vibration isolators used for damping the vibrations of rotary machines, including gyroscopic ones.

Study on the force transmissibility of vibration isolators with geometric nonlinear damping

2013 ◽  
Vol 74 (4) ◽  
pp. 1103-1112 ◽  
Author(s):  
Jingya Sun ◽  
Xiuchang Huang ◽  
Xingtian Liu ◽  
Feng Xiao ◽  
Hongxing Hua
Keyword(s):  
Nonlinear Damping ◽  
Vibration Isolators ◽  
Geometric Nonlinear ◽  
Force Transmissibility

The Damping Characteristics of Vibration Isolators Used in Gas Turbines

1977 ◽  
Vol 19 (6) ◽  
pp. 271-277 ◽  
Author(s):  
R. Holmes
Keyword(s):  
Gas Turbines ◽  
Journal Bearing ◽  
Nonlinear Damping ◽  
Common Type ◽  
Squeeze Film ◽  
Vibration Isolator ◽  
Vibration Isolators ◽  
Damping Coefficients ◽  
Damping Characteristics ◽  
Linear Damping

The linear and nonlinear damping performance of a common type of gas-turbine vibration isolator, consisting of a squeeze-film journal bearing in parallel with a linear retainer spring, is computed and used to prescribe limits to the use of linear damping coefficients.

scholarly journals SIMULATION OF NON-LINEAR CHARACTERISTICS INFLUENCE DYNAMIC ON VERTICAL RIGID GYRO ROTOR RESONANT OSCILLATIONS

2018 ◽  
Vol 6 ◽  
pp. 1094-1100
Author(s):  
Zharilkassin Iskakov
Keyword(s):  
Nonlinear Damping ◽  
Resonant Peak ◽  
Rotor Vibration ◽  
Vibration Isolators ◽  
Unbalanced Rotor ◽  
Absolute Motion ◽  
Non Linear ◽  
Linear Damping ◽  
Simulation Results ◽  
Resonance Oscillations

The influence of viscous linear and cubic nonlinear damping of an elastic support on the resonance oscillations of a vertical rigid gyroscopic unbalanced rotor is investigated. Simulation results show that linear and cubic non-linear damping can significantly dampen the main harmonic resonant peak. In non-resonant areas where the speed is higher than the critical speed, the cubic non-linear damping can slightly dampen rotor vibration amplitude in contrast to linear damping. If linear or cubic non-linear damping increase in resonant area significantly kills capacity for absolute motion, then they have little or no influence on the capacity for absolute motion in non-resonant areas. The simulation results can be successfully used to create passive vibration isolators used in rotor machines vibration damping, including gyroscopic ones.

Beneficial performance of a quasi-zero stiffness vibration isolator with generalized geometric nonlinear damping

2020 ◽  
pp. 095745652097238
Author(s):  
Chun Cheng ◽  
Ran Ma ◽  
Yan Hu
Keyword(s):  
Damping Ratio ◽  
Nonlinear Damping ◽  
Vibration Isolator ◽  
Equivalent Damping ◽  
Frequency Responses ◽  
Geometric Nonlinear ◽  
Resonant Region ◽  
Force Transmissibility ◽  
Isolation Performance ◽  
Force And Displacement Transmissibility

Generalized geometric nonlinear damping based on the viscous damper with a non-negative velocity exponent is proposed to improve the isolation performance of a quasi-zero stiffness (QZS) vibration isolator in this paper. Firstly, the generalized geometric nonlinear damping characteristic is derived. Then, the amplitude-frequency responses of the QZS vibration isolator under force and base excitations are obtained, respectively, using the averaging method. Parametric analysis of the force and displacement transmissibility is conducted subsequently. At last, two phenomena are explained from the viewpoint of the equivalent damping ratio. The results show that decreasing the velocity exponent of the horizontal damper is beneficial to reduce the force transmissibility in the resonant region. For the case of base excitation, it is beneficial to select a smaller velocity exponent only when the nonlinear damping ratio is relatively large.

Energy flow and performance evaluation of inerter-based vibration isolators mounted on finite and infinite flexible foundation structures

2022 ◽  
Vol 14 (1) ◽  
pp. 168781402110704
Author(s):  
Zhuang Dong ◽  
Jian Yang ◽  
Chendi Zhu ◽  
Dimitrios Chronopoulos ◽  
Tianyun Li
Keyword(s):  
Power Flow ◽  
Vibration Isolation ◽  
Vibration Suppression ◽  
Flow Behavior ◽  
Flexible Beam ◽  
Vibration Isolators ◽  
Force Transmissibility ◽  
And Performance ◽  
Flexible Foundation ◽  
Isolation Performance

This study investigates the vibration power flow behavior and performance of inerter-based vibration isolators mounted on finite and infinite flexible beam structures. Two configurations of vibration isolators with spring, damper, and inerter as well as different rigidities of finite and infinite foundation structures are considered. Both the time-averaged power flow transmission and the force transmissibility are studied and used as indices to evaluate the isolation performance. Comparisons are made between the two proposed configurations of inerter-based isolators and the conventional spring-damper isolators to show potential performance benefits of including inerter for effective vibration isolation. It is shown that by configuring the inerter, spring, and damper in parallel in the isolator, anti-peaks are introduced in the time-averaged transmitted power and force transmissibility at specific frequencies such that the vibration transmission to the foundation can be greatly suppressed. When the inerter is connected in series with a spring-damper unit and then in-parallel with a spring, considerable improvement in vibration isolation can be achieved near the original peak frequency while maintaining good high-frequency isolation performance. The study provides better understanding of the effects of adding inerters to vibration isolators mounted on a flexible foundation, and benefits enhanced designs of inerter-based vibration suppression systems.

scholarly journals Analysis and design of the power law damping based on the nonlinear vessel isolation system

2018 ◽  
Vol 10 (12) ◽  
pp. 168781401881719 ◽  
Author(s):  
You Wang ◽  
Xinghua Zhu ◽  
Rong Zheng ◽  
Zhe Tang ◽  
Bingbing Chen
Keyword(s):  
Resonant Frequency ◽  
Working Conditions ◽  
Power Law ◽  
Nonlinear Damping ◽  
Frequency Region ◽  
Isolation System ◽  
Analysis And Design ◽  
Force Transmissibility ◽  
Isolation Systems ◽  
Isolation Performance

In this study, the applications of the cubic power law damping in vessel isolation systems are investigated. The isolation performance is assessed using the force transmissibility of the vessel isolation system, which is simplified as a multiple-degree-of-freedom system with two parallel freedoms. The force transmissibilities of different working conditions faced in practice are discussed by applying the cubic power law damping on different positions of the vessel isolation system. Numerical results indicate that by adding the cubic power law damping to an appropriate position, the isolation system can not only suppress the force transmissibility over the resonant frequency region but also keep the force transmissibility unaffected at the nonresonant frequency region. Moreover, the design of the nonlinear vessel isolation system is discussed by finding the optimal nonlinear damping of the isolation system.

Matching Analysis on Main Parameter for the Shock Absorber Development Process

2013 ◽  
Vol 694-697 ◽  
pp. 393-398 ◽  
Author(s):  
Gang Liu ◽  
Si Zhong Chen ◽  
Hong Bin Ren
Keyword(s):  
Shock Absorber ◽  
Piecewise Linear ◽  
Nonlinear Damping ◽  
Control Mode ◽  
Nonlinear Dynamic Model ◽  
Nonlinear Characteristics ◽  
Car Suspension ◽  
Numerical Simulation Methods ◽  
Road Excitation ◽  
Vehicle Suspension System

Considering nonlinear characteristics of springiness and damping element, the quarter-car suspension nonlinear dynamic model is established with ADAMS. The simulation model of suspension established, and the simulation curve of nonlinear suspension is gotten by using the numerical simulation methods. The target parameters of the piecewise linear three stage control mode of the shock absorber are studied under the different random road excitation, it would provide the theoretical basic for the nonlinear damping matching of the vehicle suspension system.

Improved Feasible Load Range and Its Effect on the Frequency Response of Origami-Inspired Vibration Isolators With Quasi-Zero-Stiffness Characteristics1

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Kazuya Inamoto ◽  
Sachiko Ishida
Keyword(s):  
Numerical Analysis ◽  
Vibration Isolator ◽  
Spring Stiffness ◽  
Frequency Range ◽  
Torsional Buckling ◽  
Load Range ◽  
Nonlinear Characteristics ◽  
Vibration Isolators ◽  
Initial Load ◽  
Linear Spring

We describe herein a method for extending the load range of a vibration isolator using a foldable cylinder consisting of a torsional buckling pattern and evaluate the vibration isolating performance through excitation experiments. A previous study determined that the foldable cylinder is bistable and acts as a vibration isolator with nonlinear characteristics in a displacement region, where the spring stiffness is zero. Its spring characteristics and vibration isolating performance were clarified by numerical analysis and excitation experiments. The findings indicated that the vibration in a certain frequency range is reduced where the spring stiffness is zero. However, this vibration isolator has a disadvantage in that it can only support an initial load that transfers to the zero-spring-stiffness region. Therefore, in this research, we improve the position of the linear spring attached to the isolator. As a result, the initial load range is extended by two to four times that of the conventional vibration isolator. Furthermore, the isolating performance is maintained even when the initial load is changed within a given load range.

scholarly journals Stochastic dynamic for an extensible beam equation with localized nonlinear damping and linear memory

2020 ◽  
Vol 4 (1) ◽  
pp. 400-416
Author(s):  
Abdelmajid Ali Dafallah ◽  
◽  
Fadlallah Mustafa Mosa ◽  
Mohamed Y. A. Bakhet ◽  
Eshag Mohamed Ahmed ◽  
...  
Keyword(s):  
Nonlinear Damping ◽  
Random Attractor ◽  
Beam Equation ◽  
Stochastic Dynamic ◽  
Uniqueness Of Solutions ◽  
Stochastic Dynamical System ◽  
Autonomous Case ◽  
Bounded Absorbing Set ◽  
Linear Damping ◽  
Longtime Behavior

In this paper, we concerned to prove the existence of a random attractor for the stochastic dynamical system generated by the extensible beam equation with localized non-linear damping and linear memory defined on bounded domain. First we investigate the existence and uniqueness of solutions, bounded absorbing set, then the asymptotic compactness. Longtime behavior of solutions is analyzed. In particular, in the non-autonomous case, the existence of a random attractor attractors for solutions is achieved.

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