Design and Dynamic Characteristics of a Torsion Isolator With Negative Stiffness Structures

2016 ◽  
Author(s):  
Hui Liu ◽  
Xiaojie Wang ◽  
Weida Wang ◽  
Changle Xiang
Keyword(s):  
Harmonic Balance ◽  
Vibration Isolation ◽  
Harmonic Balance Method ◽  
Negative Stiffness ◽  
Frequency Range ◽  
Disk Structure ◽  
Vibration Transmissibility ◽  
Low Stiffness ◽  
Vibration Isolation Performance ◽  
Isolation Performance

This paper proposes a torsion isolator with negative stiffness structures, which has low stiffness. The torsion isolator has been designed into disk structure, which is the installation position of the positive springs and negative stiffness structures. In this paper, the model of the torsion isolator is introduced firstly, and the nonlinear stiffness and torque are studied under different compression deformation of springs in negative stiffness structures. Then a two-degree-freedom equation of the torsional isolator is established and vibration transmissibility is obtained by using Harmonic Balance Method. Theoretical analysis results show that the isolator with negative stiffness structures has larger isolation frequency range than linear isolator. Finally, an initial experiment is completed. The experimental results show that the isolator has a good vibration isolation performance.

scholarly journals Design of cab seat suspension system for construction machinery based on negative stiffness structure

2021 ◽  
Vol 13 (8) ◽  
pp. 168781402110449
Author(s):  
Xin Liao ◽  
Xiaofei Du ◽  
Shaohua Li
Keyword(s):  
Vibration Isolation ◽  
Ride Comfort ◽  
Suspension System ◽  
Negative Stiffness ◽  
Construction Machinery ◽  
Seat Suspension ◽  
Vibration Transmissibility ◽  
Suspension Structure ◽  
Vibration Isolation Performance ◽  
Isolation Performance

In order to improve the vibration isolation performance of cab seat and ride comfort of the driver, a seat suspension structure of construction machinery cab is proposed based on negative stiffness structure (NSS) in this paper. The influences of different parameters of suspension system on dynamic stiffness are analyzed. The configuration parameter range of suspension system is obtained. Then, the nonlinear dynamic equation of the seat suspension system is established and the NSS optimization model is proposed. The vibration transmissibility characteristics of suspension structure are analyzed by different methods. The results show that the displacement and acceleration amplitude of optimized seat suspension system are obviously reduced, and the VDV and RMS in the vertical vibration direction for the seat are respectively decreased by 87% and 86%. The vibration transmissibility rate SEAT and the Ttrans are both decreased. Moreover, the peak frequencies of the vibration transmitted to the driver are not near the key frequency values which are easy to cause human discomfort. It indicates that the design of seat suspension system has no effect on the health condition of the driver after being vibrated. The advantages of vibration isolation performance of the designed NSS suspension system are demonstrated, improving the driver’s ride comfort and the working environment.

Optimization of Vehicle Powertrain Mounting System and its Performance

2013 ◽  
Vol 441 ◽  
pp. 580-583
Author(s):  
Gong Yu Pan ◽  
Xin Yang ◽  
You Yan
Keyword(s):  
Vibration Isolation ◽  
Dynamics Model ◽  
Acceleration Response ◽  
Idle State ◽  
Decoupling Method ◽  
Before And After ◽  
Vibration Transmissibility ◽  
Six Degree Of Freedom ◽  
Vibration Isolation Performance ◽  
Isolation Performance

In order to solve the vibration problem of diesel engine powertrain assembly at its idle state, a six degree-of-freedom dynamics model of the powertrain mounting system is established and a optimization based on Adams/View is applied to simulation and analysis on the powertrain mounting system with energy decoupling method. The results show that the optimized repositioning mounts installation position can effectively improve decoupling rate in main vibration directions of mounting system. Based on this, the vibration transmissibility and acceleration response before and after optimization are simulated. The results show that the optimized engine mounting system makes a great improvement of vibration isolation performance.

scholarly journals High-Efficiency Vibration Isolation for a Three-Phase Power Transformer by a Quasi-Zero-Stiffness Isolator

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Hao Cao ◽  
Yaopeng Chang ◽  
Jiaxi Zhou ◽  
Xuhui Zhao ◽  
Ling Lu ◽  
...  
Keyword(s):  
Vibration Isolation ◽  
High Efficiency ◽  
Power Transformer ◽  
Dynamic Stiffness ◽  
Harmonic Balance Method ◽  
Isolation System ◽  
Three Phase ◽  
Engineering Practices ◽  
Vibration Isolation Performance ◽  
Isolation Performance

The vibrations generated by a three-phase power transformer reduce the comfort of residents and the service life of surrounding equipment. To resolve this tough issue, a quasi-zero-stiffness (QZS) isolator for the transformer is proposed. This paper is devoted to developing a QZS isolator in a simple way for engineering practices. The vertical springs are used to support the heavy weight of the transformer, while the oblique springs are employed to fulfill negative stiffness to neutralize the positive stiffness of the vertical spring. Hence, a combination of the vertical and oblique spring can yield high static but low dynamic stiffness, and the vibration isolation efficiency can be improved substantially. The dynamic analysis for the QZS vibration isolation system is conducted by the harmonic balance method, and the vibration isolation performance is estimated. Finally, the prototype of the QZS isolator is manufactured, and then the vibration isolation performance is tested comparing with the linear isolator under real power loading conditions. The experimental results show that the QZS isolator prominently outperforms the existing linear isolator. This is the first time to devise a QZS isolator for three-phase power transformers with heavy payloads in engineering practices.

A Study of a Pendulum-Like Vibration Isolator With Quasi-Zero-Stiffness

2021 ◽  
Author(s):  
Yishen Tian ◽  
Dengqing Cao ◽  
Yan Wang
Keyword(s):  
Harmonic Balance ◽  
Geometric Nonlinearity ◽  
Harmonic Balance Method ◽  
The Novel ◽  
Vibration Isolator ◽  
Frequency Range ◽  
Jump Phenomenon ◽  
Isolation Performance ◽  
Force And Displacement Transmissibility ◽  
Better Than

Abstract This article introduces a pendulum element to a 3-spring vibration isolator to achieve a high-static-low-dynamic (HSLD) stiffness or even quasi-zero stiffness (QZS) around the equilibrium position. Numerical simulation is given and the harmonic balance method (HBM) is used to obtain time responses for analysis. Effects of different parameters on the isolation performance are studied and summarized. Approximation force and displacement transmissibility of the system are calculated to evaluate the isolation performance. Comparisons are made with those of an equivalent linear isolator and the typical 1 degree-of-freedom (DOF) QZS isolator. Results show that the novel vibration isolator performs better than existing isolators under selected parameters. The left bent backbone of the novel isolator demonstrates evident softening geometric nonlinearity. Therefore, it achieves a wider frequency range of isolation than the linear 1DOF isolator and typical 3-spring QZS isolator. Moreover, the transmissibility of the novel isolator is smaller at higher frequencies as the jump phenomenon occurs on the left.

An innovative X-shaped vibration isolation mount with tunable quasi-zero-stiffness property

2021 ◽  
Vol 263 (3) ◽  
pp. 3011-3022
Author(s):  
Jing Bian ◽  
Xingjian Jing ◽  
Yishen Tian
Keyword(s):  
Vibration Isolation ◽  
Negative Stiffness ◽  
Design Parameters ◽  
Property A ◽  
Vibration Displacement ◽  
Stiffness Property ◽  
Passive Vibration Isolation ◽  
Engineering Practices ◽  
Vibration Isolation Performance ◽  
Isolation Performance

Passive vibration isolation is always preferable in many engineering practices. To this aim, an innovative, compact, and passive vibration isolation mount is studied in this paper. The novel mount is adjustable to different payloads due to a special oblique and tunable stiffness mechanism, and of high vibration isolation performance with a wider quasi-zero-stiffness range due to the deliberate employment of negative stiffness of the X-shaped structure. The X-shaped structure has been well studied recently due to its excellent nonlinear stiffness and damping properties. In this study, by using of the negative stiffness property within the X-shaped structure, the X-shaped mount (X-mount) can have an obviously larger vibration displacement range which maintains the quasi-zero-stiffness property. A special oblique spring is thus introduced such that the overall equivalent stiffness can be much easily adjusted. Systematic parametric study is conducted to reveal the critical design parameters and their relationship with vibration isolation performance. A prototype and experimental validations are implemented to validate the theoretical results. It is believed that the X-mount would provide an innovative technical upgrade to many existing vibration isolation mounts in various engineering practices and it could also be the first prototyped mount which can offer adjustable quasi-zero stiffness conveniently.

scholarly journals An Asymmetric Quasi-zero Stiffness Vibration Isolator with Long Stroke and Large Bearing Capacity

2021 ◽  
Author(s):  
Xinghua Zhou ◽  
Dingxuan Zhao ◽  
Xiao Sun ◽  
Xiao Yang ◽  
Jianhai Zhang ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Vibration Isolation ◽  
Geometrical Nonlinearity ◽  
Harmonic Balance Method ◽  
Nonlinear Damping ◽  
Vibration Isolator ◽  
Plate Spring ◽  
Supporting Force ◽  
Vibration Isolation Performance ◽  
Isolation Performance

Abstract A novel passive asymmetric quasi-zero stiffness vibration isolator (AQZS-VI) comprising two linear springs acting in parallel with one negative stiffness element (NSE) is proposed, of which the NSE is mainly constructed by the combination of cantilever plate spring and L-shaped lever (CPS-LSL). The static model of the isolator is deduced considering the geometrical nonlinearity of the NSE and the bending deformation of plate spring. The nonlinear stiffness properties of the CPS-LSL and the AQZS-VI, as well as the nonlinear damping properties of the AQZS-VI are discussed. The absolute displacement transmissibility of the AQZS-VI under base displacement excitation is obtained using Harmonic Balance Method, and the effects of different excitation amplitudes and damping factors on the vibration isolation performance are analyzed. Better than other quasi-zero stiffness vibration isolators (QZS-VI) whose NSEs do not provide supporting force at zero stiffness point, the NSE of the AQZS-VI provides more supporting force than the parallel connected linear springs, which is very beneficial for improving the bearing capacity of the isolator. Compared with a typical symmetric QZS-VI with same damping property, the AQZS-VI has longer stroke with low stiffness and lower peak value of displacement transmissibility. The prototype experiments indicate that the AQZS-VI outperforms the linear counterpart with much smaller starting frequency of vibration isolation and lower displacement transmissibility. The proposed AQZS-VI has great potential for applying in various engineering practices with superior vibration isolation performance.

scholarly journals Theoretical Modeling and Vibration Isolation Performance Analysis of a Seat Suspension System Based on a Negative Stiffness Structure

2021 ◽  
Vol 11 (15) ◽  
pp. 6928
Author(s):  
Xin Liao ◽  
Ning Zhang ◽  
Xiaofei Du ◽  
Wanjie Zhang
Keyword(s):  
Vibration Isolation ◽  
Vibration Suppression ◽  
Ride Comfort ◽  
Dynamic Stiffness ◽  
Suspension System ◽  
Negative Stiffness ◽  
Nonlinear Dynamic Model ◽  
Seat Suspension ◽  
Vibration Isolation Performance ◽  
Isolation Performance

In this study, to improve the vibration isolation performance of a cab seat and the ride comfort of the driver, we propose a mathematical model for a seat suspension system of a construction machinery cab based on a negative stiffness structure (NSS). First, a static analysis of a seat suspension system is conducted and the different parameters and their influences on the dynamic stiffness are discussed. Thereby, the ideal configuration parameter range of the suspension system is obtained. Moreover, the nonlinear dynamic model of the designed seat suspension system is established. The frequency response and the stability are analyzed by using the HBM method and numerical simulation. The vibration transmissibility characteristics and vibration suppression effects of the seat suspension system are presented in detail. The results show that, as compared with a quasi-zero-stiffness system, the QZS-IE system has higher vibration suppression advantages under large excitation and small damping, as well as lower transmissibility and a wider vibration isolation frequency range. In addition, an inerter element with a larger mass ratio and relatively shorter distance ratio is better for vibration isolation performance of the QZS-IE system in a practical engineering application. The results of this study provide a scientific basis for the design and improvement of a seat suspension system.

scholarly journals Theoretical Design of a Novel Vibration Energy Absorbing Mechanism for Cables

2020 ◽  
Vol 10 (15) ◽  
pp. 5309
Author(s):  
Zhen Qin ◽  
Yu-Ting Wu ◽  
Aihua Huang ◽  
Sung-Ki Lyu ◽  
John W. Sutherland
Keyword(s):  
Vibration Isolation ◽  
Harmonic Balance Method ◽  
Hydraulic Cylinder ◽  
Vibration Energy ◽  
Single Degree Of Freedom ◽  
Environmental Vibration ◽  
Energy Absorbing ◽  
Vibration Isolation Performance ◽  
Isolation Performance ◽  
Novel Design

A novel design of a vibration energy absorbing mechanism (VEAM) that is based on multi-physics (magnetic spring, hydraulic system, structural dynamics, etc.) for cable vibration is proposed. The minimum working force of the hydraulic cylinder has been exploited in this design in order to combine a non-linear stiffness vibration isolation module that is composed of permanent magnetic springs with hydraulic viscous vibration damping modules. In response to different environmental vibration impacts, VEAM can automatically switch the vibration control modes without an electronic mechanism. Additionally, the non-contact design effectively reduces the wear that is induced by the reciprocating motion of the small amplitude of the hydraulic viscous dampers. The proposed mechanism is explained and a theoretical model is established. The transmissibility of the two modules at a single degree of freedom is derived using the harmonic balance method. After that, a series of variable control numerical simulations were performed for each important parameter. Empirical rules for designing the system were created by comparing the influence of each parameter on the vibration isolation performance of the entire system.

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