A nonlinear stiffness and nonlinear inertial vibration isolator

2020 ◽  
pp. 107754632094092
Author(s):  
Yong Wang ◽  
Hao-Xuan Li ◽  
Chun Cheng ◽  
Hu Ding ◽  
Li-Qun Chen
Keyword(s):  
Dynamic Response ◽  
High Frequency ◽  
Nonlinear Stiffness ◽  
Vibration Isolator ◽  
Dynamic Displacement ◽  
Isolation Frequency ◽  
Inertial Characteristic ◽  
Force Transmissibility ◽  
Isolation Performance ◽  
Displacement Peak

A nonlinear stiffness and nonlinear inertial vibration isolator is proposed in this article. It consists of an inerter, a damper, and spring elements. The nonlinear stiffness characteristic is achieved through a negative stiffness structure based on the diamond-shaped structure that generates nonlinear displacement terms. The nonlinear inertial characteristic is implemented via a geometrical nonlinear inerter that produces a nonlinear acceleration term and a nonlinear quadratic velocity term. An averaging method is developed to analyze approximately the dynamic response. The isolation performance is evaluated using four performance criteria: dynamic displacement peak, force transmissibility peak, isolation frequency band, and high-frequency force transmissibility. The effects of the nonlinear inertial characteristic on the dynamic response and isolation performance are examined. The results show that the backbone curve of the nonlinear stiffness and nonlinear inertial vibration isolator has two changing trends: bending first to the right and then to the left and bending directly to the left. The corresponding frequency response curve displays linear, hardening, and softening characteristics. The isolation performance of the nonlinear stiffness and nonlinear inertial vibration isolator is compared with that of the nonlinear stiffness and nonlinear stiffness and linear inertial ones. It could achieve a smaller force transmissibility peak, lower resonant frequency, and larger isolation frequency band than the nonlinear stiffness one and could have smaller dynamic displacement peak and smaller high-frequency force transmissibility than the nonlinear stiffness and linear inertial one. The proposed nonlinear stiffness and nonlinear inertial vibration isolator achieves a better integrated isolation performance among the three vibration isolators.

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.

Application of a dynamic antiresonant vibration isolator to minimize the vibration transmission in underwater vehicles

2017 ◽  
Vol 24 (17) ◽  
pp. 3819-3829 ◽  
Author(s):  
Niuniu Liu ◽  
Chenyang Li ◽  
Caiyu Yin ◽  
Xingjian Dong ◽  
Hongxing Hua
Keyword(s):  
Power Flow ◽  
Thrust Bearing ◽  
Vibration Mode ◽  
Underwater Vehicle ◽  
Vibration Isolator ◽  
Harmonic Force ◽  
Vibration Transmission ◽  
Force Transmissibility ◽  
Isolation Performance ◽  
Analytical Dynamic

Harmonic axial force resulting from a propeller’s first vibration mode is a major cause of tonal sound radiation of an underwater vehicle. To reduce the harmonic force, we employ a dynamic antiresonant vibration isolator (DAVI) in parallel with thrust bearing of the shafting system to attenuate vibration transmitted to the hull. The methods of transfer matrices and substructure synthesis are used to create a semi-analytical dynamic model of the propeller–shaft–hull system with DAVI. In this model, the elastic properties of the propeller and foundation are taken into consideration. The force transmissibility and power flow are then used to evaluate the isolation performance of the DAVI. For the purpose of comparison, a resonance changer (RC) proposed in the published literature is also used to reduce the axial vibration transmission. It is demonstrated numerically that by using DAVI, the vibration and power flow of the underwater vehicle are greatly attenuated at the designed frequency without obviously changing the axial fundamental resonance frequency of the shafting system, which is superior to the RC isolator.

A new model of a hydraulic leveraged dynamic anti-resonance vibration isolator under base excitation: A theoretical and experimental study

2019 ◽  
Vol 25 (16) ◽  
pp. 2282-2292 ◽  
Author(s):  
Niuniu Liu ◽  
Zeyu Jin ◽  
Hongxing Hua
Keyword(s):  
Mathematical Model ◽  
Experimental Study ◽  
Vibration Isolation ◽  
Resonance Vibration ◽  
Vibration Isolator ◽  
Base Excitation ◽  
New Model ◽  
Isolation Frequency ◽  
Designed Experiment ◽  
Isolation Performance

Two models have previously been commonly used to predict the isolation performance of a hydraulic leveraged dynamic anti-resonance vibration isolator. The models have deficiencies, however, in considering the volumetric stiffness of the isolator. In this paper, a new model is proposed to improve the accuracy by reasonably taking the volumetric stiffness into consideration. The model is validated by a carefully designed experiment. The influence of the volumetric stiffness on the isolation performance of the isolator is investigated by the validated model. The results indicate that the volumetric stiffness of the isolator and its location in a mathematical model have a significant influence on the isolation frequency and the second natural frequency of the isolator. The dependence of the volumetric stiffness on the isolation frequency, the attenuation capacity at the isolation frequency, and the bandgap of the isolator is presented. The investigation will enhance the understanding of the hydraulic leveraged dynamic anti-resonance vibration isolator, and facilitate the design and exploitation of this type of isolator in the field of vibration isolation.

scholarly journals Sensitivity with Respect to the Path Parameters and Nonlinear Stiffness of Vibration Transfer Path Systems

2010 ◽  
Vol 2010 ◽  
pp. 1-11
Author(s):  
Yimin Zhang ◽  
Xianzhen Huang
Keyword(s):  
Dynamic Response ◽  
Time Domain ◽  
Evaluation Criteria ◽  
Nonlinear Stiffness ◽  
Vibration System ◽  
Transfer Path ◽  
Dynamic Sensitivity ◽  
The Time Domain

Generally speaking, a vibration system consists of three parts: vibration resource, vibration transfer path, and vibration receiver. Based on the dynamic sensitivity technique, this paper proposes a method for evaluating the contribution of each vibration transfer path to the dynamic response of the vibration receiver. Nonlinear stiffness is an important factor in causing the nonlinearity of vibration systems. Taking sensitivity as the evaluation criteria, we present an effective approach for estimating the influence of nonlinear stiffness in vibration transfer paths on the dynamic response of the vibration receiver. Using the proposed method, the sensitivity of the vibration system with multiple and/or multidimensional transfer paths could be determined in the time domain.

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.

Vibration control of an unbalanced system using a quasi-zero stiffness vibration isolator with fluidic actuators and composite material: An experimental study

2022 ◽  
pp. 107754632110514
Author(s):  
Sivakumar Solaiachari ◽  
Jayakumar Lakshmipathy
Keyword(s):  
Composite Material ◽  
Nonlinear Vibration ◽  
Vibration Isolation ◽  
Basalt Fiber ◽  
Experimental Investigations ◽  
Vibration Isolator ◽  
Coil Spring ◽  
Linear Type ◽  
Fluidic Actuators ◽  
Isolation Performance

In this study, a new type of vibration isolator based on fluidic actuators and a composite slab was tested experimentally with an unbalanced disturbance. Quasi-zero stiffness vibration isolation techniques are advanced and provide effective isolation performance for non-nominal loads. The isolation performance of the proposed isolator was compared to that of a nonlinear vibration isolator equipped with fluidic actuators and a mechanical coil spring (NLVIFA). The NLVIFA system is better suited to non-nominal loads; however, the mechanical spring axial deflection leads to limited amplitude reduction in the system. To address this issue, a cross buckled slab was developed to replace a mechanical coil spring for absorbing vertical deflection by transverse bending, which is made of a specially developed composite material of Basalt fiber reinforced with epoxy resin and enhanced with graphene nano pellets. This current study was concerned with the theoretical analysis and experimental investigations of the proposed nonlinear vibration isolator with fluidic actuators and composite material (NLVIFA-CM), which performs under quasi-zero stiffness characteristics. Because of its reduced axial deflection, the theoretical and experimental results show that the NLVIFA-CM system outperforms the NLVIFA system and other linear type vibration isolators in terms of isolation performance. Furthermore, the proposed vibration isolator makes a significant contribution to low-frequency vibration.

Vibration isolation performance of nonobstructive particle damping in a machine rack

2018 ◽  
Vol 25 (5) ◽  
pp. 1122-1130 ◽  
Author(s):  
Zhanpeng Zheng ◽  
Chengjun Wu ◽  
Hengliang Wu ◽  
Jianyong Wang ◽  
Xiaofei Lei
Keyword(s):  
Theoretical Model ◽  
Dynamic Response ◽  
Vibration Isolation ◽  
Passive Control ◽  
Vibration Energy ◽  
Damping Force ◽  
Damping Effect ◽  
Particle Damping ◽  
Vibration Isolation Performance ◽  
Isolation Performance

Nonobstructive particle damping (NOPD) is a novel passive control technology with strong nonlinear-damping. Many scholars put effort into the research on the internal mechanism of NOPD. In contrast, the application of NOPD to engineering has not received much research effort. A theoretical model based on the principle of gas–solid flows, which is employed to evaluate damping effect of NOPD and to predict dynamic response of a machine rack by a co-simulation approach, is established in this paper. In view of the difference between damping effect acting on the lateral and bottom of NOPD holes directly, total damping force is divided into lateral damping force and bottom damping force according to the Janssen theory of stress changed direction. Moreover, NOPD technology is applied to a machine rack for discussing its vibration isolation performance. The results indicate that NOPD technology can suppress the intense vibration, especially between 4000 Hz and 8000 Hz. It is noted that the theoretical model of NOPD can accurately predict the dynamic response of the machine rack with NOPD. The 1/3 Octave vibration energy spectrum indicates that NOPD technics can dissipate the vibration energy of the machine rack at full frequency, especially in 31.5 Hz, and attenuation up to 39.75 dB.

Design and Experimental Analysis of Origami-Inspired Vibration Isolator With Quasi-Zero-Stiffness Characteristic

2017 ◽  
Vol 139 (5) ◽  
Author(s):  
Sachiko Ishida ◽  
Kohki Suzuki ◽  
Haruo Shimosaka
Keyword(s):  
Pacific Ocean ◽  
Experimental Analysis ◽  
Frequency Region ◽  
Vibration Isolator ◽  
Spring Stiffness ◽  
Torsional Buckling ◽  
Harmonic Oscillations ◽  
Stiffness Characteristic ◽  
Current Specification ◽  
Isolation Performance

We present a prototype vibration isolator whose design is inspired by origami-based foldable cylinders with torsional buckling patterns. The vibration isolator works as a nonlinear spring that has quasi-zero spring stiffness in a given frequency region, where it does not transmit vibration in theory. We evaluate the performance of the prototype vibration isolator through excitation experiments via the use of harmonic oscillations and seismic-wave simulations of the Tohoku-Pacific Ocean and Kobe earthquakes. The results indicate that the isolator with the current specification is able to suppress the transmission of vibrations with frequencies of over 6 Hz. The functionality and constraints of the isolator are also clarified. It has been known that origami-based foldable cylinders with torsional buckling patterns provide bistable folding motions under given conditions. In a previous study, we proposed a vibration isolator utilizing the bistability characteristics and numerically confirmed the device's validity as a vibration isolator. Here, we attempt prototyping the isolator with the use of versatile metallic components and experimentally evaluate the isolation performance.

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.

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