Research on dynamic stiffness of the damping element in bellows-type fluid viscous damper by a simplified model

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xiaolei Jiao ◽  
Jinxiu Zhang ◽  
Hongchao Zhao ◽  
Yong Yan
Keyword(s):  
Frequency Domain ◽  
Analytical Model ◽  
High Frequency ◽  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Simplified Model ◽  
Viscous Damper ◽  
Content Type ◽  
Fluid Viscous Damper ◽  
Frequency Domains

Purpose Bellows-type fluid viscous damper can be used to isolate micro vibration in high-precision satellites. The conventional model cannot describe hydraulic stiffness in the medium- and high-frequency domain of this damper. A simplified analytical model needs to be established to analyze hydraulic stiffness of the damping element in this damper. Design/methodology/approach In this paper, a bellows-type fluid viscous damper is researched, and a simplified model of the damping element in this damper is proposed. Based on this model, the hydraulic stiffness and damping of this damper in the medium- and high-frequency domains are studied, and a comparison is made between the analytical model and a finite element model to verify the analytical model. Findings The results show that when silicone oil has low viscosity, a model that considers the influence of the initial segment of the damping orifice is more reasonable. In the low-frequency domain, hydraulic stiffness increases quickly with frequency and remains stable when the frequency increases to a certain value; the stable stiffness can reach 106 N/m, which is much higher than the main stiffness. Excessive dynamic stiffness in the high-frequency domain will cause poor vibration isolation performance. Adding compensation bellows to the end of the original isolator may be an effective solution. Practical implications A model of the isolator containing the compensation bellows can be derived based on this analytical model. This research can also be used for dynamic modeling and vibration isolation performance analysis of a vibration isolation platform based on this bellows-type fluid viscous damper. Originality/value This paper proposed a simplified model of damping element in bellows-type fluid viscous damper, which can be used to analyze hydraulic stiffness in this damper and it was found that this damper showed stable hydraulic stiffness in the medium- and high-frequency domains.

scholarly journals Dynamic characterization of controlled multi-channel semi-active magnetorheological fluid mount

2021 ◽  
Vol 12 (2) ◽  
pp. 751-764
Author(s):  
Zhihong Lin ◽  
Mingzhong Wu
Keyword(s):  
High Frequency ◽  
Optimization Design ◽  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Low Frequency ◽  
Vehicle Model ◽  
Mr Fluid ◽  
Unbalanced Force ◽  
Low Frequency Vibration ◽  
Engine Mount

Abstract. In this paper, a novel structure of a controlled multi-channel semi-active magnetorheological (MR) fluid mount is proposed, including four controlled channels and one rate-dip channel. Firstly, the magnetic circuit analysis, rate-dip channel optimization design, and MR fluid mount damping analysis are given. Secondly, the mathematical model of the controlled multi-channel semi-active MR fluid mount is constructed. We analyze the effect of controlled multi-channel closing on the dynamic characteristics of the mounts and the effect of the presence or absence of the rate-dip channel on the low-frequency isolation of the mount. Finally, the controlled multi-channel semi-active MR fluid mount was applied to the 1/4 vehicle model (a model consisting of an engine, a single engine mount, a single suspension and a vehicle frame), with the transmissibility of the engine relative to the vehicle frame at low frequency and the transmissibility of the engine reciprocating unbalanced force to the vehicle frame magnitude at high frequency as the evaluation index. Numerical simulation shows the following points. (1) The controllable multi-channel semi-active MR fluid mount can achieve adjustable dynamic stiffness and damping with applied 2 A current to different channels. (2) With known external excitation source, applied currents to different controllable channels can achieve the minimum transmissibility and meet the mount wide-frequency vibration isolation requirement, while adding a rate-dip channel can improve the low-frequency vibration isolation performance of the MR fluid mount. (3) Switching and closing different controllable channels in the 1/4 vehicle model can achieve the minimum transmissibility of low-frequency engine vibrations relative to the vehicle frame and high-frequency engine vibrations reciprocating an unbalanced force to the vehicle frame. Therefore, the design of the controllable multi-channel semi-active MR fluid mount can meet the wide-frequency isolation.

scholarly journals Research on the Impediment to Vibration Wave Propagation of Pipe from a vibration isolation mass

2019 ◽  
Vol 288 ◽  
pp. 01002
Author(s):  
Gong Yufeng ◽  
Peng Weicai ◽  
Zhang Junjie ◽  
Liu Zhizhong
Keyword(s):  
Wave Propagation ◽  
Numerical Analysis ◽  
Frequency Domain ◽  
High Frequency ◽  
Vibration Isolation ◽  
Rotational Inertia ◽  
Analysis Method ◽  
Damping Effect ◽  
Vibration Wave ◽  
Pipe Vibration

In order to control the pipe vibration, the performance of flexible connection with vibration isolation mass in impeding vibration wave propagation is studied. Based on the principle of impedance mismatching and numerical analysis method, the influences of vibration isolation mass and rotational inertia on the vibration wave propagation in pipe were discussed. The results show that the isolation mass is good at reducing the vibration of wave transmission in intermediate and high frequency domain. Meanwhile, The larger rotational inertia of the isolation mass, the better the damping effect. A useful reference was provided for the application of flexible connection to the vibration isolation and noise reduction of ship pipe.

scholarly journals Study on mechanism and filter efficacy of AGO/IAGO in the frequency domain

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Changhai Lin ◽  
Zhengyu Song ◽  
Sifeng Liu ◽  
Yingjie Yang ◽  
Jeffrey Forrest
Keyword(s):  
Frequency Domain ◽  
High Frequency ◽  
Statistical Data ◽  
Low Frequency ◽  
Digital Signal ◽  
Good Effect ◽  
Data Sequence ◽  
Content Type ◽  
Noise Interference ◽  
Long Period

PurposeThe purpose of this paper is to analyze the mechanism and filter efficacy of accumulation generation operator (AGO)/inverse accumulation generation operator (IAGO) in the frequency domain.Design/methodology/approachThe AGO/IAGO in time domain will be transferred to the frequency domain by the Fourier transform. Based on the consistency of the mathematical expressions of the AGO/IAGO in the gray system and the digital filter in digital signal processing, the equivalent filter model of the AGO/IAGO is established. The unique methods in digital signal processing systems “spectrum analysis” of AGO/IAGO are carried out in the frequency domain.FindingsThrough the theoretical study and practical example, benefit of spectrum analysis is explained, and the mechanism and filter efficacy of AGO/IAGO are quantitatively analyzed. The study indicated that the AGO is particularly suitable to act on the system's behavior time series in which the long period parts is the main factor. The acted sequence has good effect of noise immunity.Practical implicationsThe AGO/IAGO has a wonderful effect on the processing of some statistical data, e.g. most of the statistical data related to economic growth, crop production, climate and atmospheric changes are mainly affected by long period factors (i.e. low-frequency data), and most of the disturbances are short-period factors (high-frequency data). After processing by the 1-AGO, its high frequency content is suppressed, and its low frequency content is amplified. In terms of information theory, this two-way effect improves the signal-to-noise ratio greatly and reduces the proportion of noise/interference in the new sequence. Based on 1-AGO acting, the information mining and extrapolation prediction will have a good effect.Originality/valueThe authors find that 1-AGO has a wonderful effect on the processing of data sequence. When the 1-AGO acts on a data sequence X, its low-pass filtering effect will benefit the information fluctuations removing and high-frequency noise/interference reduction, so the data shows a clear exponential change trends. However, it is not suitable for excessive use because its equivalent filter has poles at the non-periodic content. But, because of pol effect at zero frequency, the 1-AGO will greatly amplify the low-frequency information parts and suppress the high-frequency parts in the information at the same time.

scholarly journals Nonlinear Characteristics of Three-parameter Fluid Viscous Damper with Considering of Principal Stiffness and Hydraulic Stiffness

2021 ◽  
Author(s):  
Xiaolei Jiao ◽  
Jinxiu Zhang ◽  
Wenbo Li ◽  
Jingjing Mu
Keyword(s):  
Frequency Domain ◽  
Linear Model ◽  
Hydraulic Resistance ◽  
Nonlinear Model ◽  
Nonlinear Behavior ◽  
Resonance Peak ◽  
Correction Coefficient ◽  
Viscous Damper ◽  
Nonlinear Characteristics ◽  
Fluid Viscous Damper

Abstract The three-parameter fluid viscous damper is used to isolate micro-vibration produced by control torque gyro (CMG) in satellite. In this paper, the damper is simplified by a single tube fluid viscous damper and two springs connected to the damping piston. With consideration of the principal stiffness of the bellows and the contraction and expansion effect of the damping orifice, the approximate analytical nonlinear model of the damper is established and verified by the computation fluid mechanics (CFD) method. Based on this analytical model, the displacement response of the damper and correction coefficient of hydraulic resistance are analyzed, the nonlinear characteristics in the frequency domain are also revealed. Furthermore, the energy consumptions of the nonlinear model and linear model are researched. The results show that the damper has an obvious amplitude at the first resonance peak, but not obvious at the second resonance peak. The vibration amplitude of the damping piston is only um level in the high-frequency domain. The correction coefficient of the hydraulic resistance at the resonance peak is much higher than other frequencies, which causes a significant nonlinear behavior. In addition, the energy consumption of the nonlinear model is larger than that of the linear model at the resonance peak, and the larger the resonance peak, the more obvious the phenomenon is. This means that the nonlinear damping can be used to further improve the suppression of the resonance peak of the three-parameter fluid viscous damper.

Design and analysis of a vibration isolation system with cam–roller–spring–rod mechanism

2021 ◽  
pp. 107754632110005
Author(s):  
Yonglei Zhang ◽  
Guo Wei ◽  
Hao Wen ◽  
Dongping Jin ◽  
Haiyan Hu
Keyword(s):  
Vibration Isolation ◽  
Dynamic Stiffness ◽  
Experimental Studies ◽  
Excitation Amplitude ◽  
Isolation System ◽  
Vibration Isolation System ◽  
Stiffness Characteristic ◽  
Negative Stiffness Mechanism ◽  
Isolation Systems ◽  
Vibration Isolation Performance

The vibration isolation system using a pair of oblique springs or a spring-rod mechanism as a negative stiffness mechanism exhibits a high-static low-dynamic stiffness characteristic and a nonlinear jump phenomenon when the system damping is light and the excitation amplitude is large. It is possible to remove the jump via adjusting the end trajectories of the above springs or rods. To realize this idea, the article presents a vibration isolation system with a cam–roller–spring–rod mechanism and gives the detailed numerical and experimental studies on the effects of the above mechanism on the vibration isolation performance. The comparative studies demonstrate that the vibration isolation system proposed works well and outperforms some other vibration isolation systems.

Simplified Modeling Research of Reinforced Concrete Based on the Dynamic Stiffness Equivalence

2012 ◽  
Vol 446-449 ◽  
pp. 458-462
Author(s):  
Jie Hu ◽  
Jia Quan Feng ◽  
Xi Nong Zhang
Keyword(s):  
Reinforced Concrete ◽  
Reference Model ◽  
Dynamic Stiffness ◽  
Optimization Method ◽  
Simplified Model ◽  
Response Analysis ◽  
Reinforced Concrete Structure ◽  
Optimization Function ◽  
Nature Frequency ◽  
Simplified Modeling

This paper proposed a simplified modeling method of reinforced concrete based on the equivalence of dynamic stiffness, the parameters of simplified model were modified to make the error of nature frequency between reference model and simplified model as small as possible, and an appropriate optimization function was designed. The essentiality of the proposed method is parameter optimization, with the advantages such as fewer elements and calculation assumption. The numerical simulation result indicated that this optimization method is suitable for the dynamic response analysis of complicated reinforced concrete structure.

Posteroventral pallidotomy for midbrain tremor after a pontine hemorrhage

1999 ◽  
Vol 91 (5) ◽  
pp. 885-888 ◽  
Author(s):  
Yasushi Miyagi ◽  
Fumio Shima ◽  
Katsuya Ishido ◽  
Masashi Moriguchi ◽  
Kazufumi Kamikaseda
Keyword(s):  
Upper Extremity ◽  
High Frequency ◽  
Upper Extremities ◽  
Proximal Segment ◽  
Action Tremor ◽  
Content Type ◽  
Pontine Hemorrhage ◽  
Posteroventral Pallidotomy ◽  
Left Thalamus ◽  
Midbrain Tremor

✓ This 49-year-old man gradually developed a disabling action tremor in the proximal right upper extremity 8 months after suffering a pontine tegmental hemorrhage. The intraoperative microrecording in the nucleus ventralis intermedius (VIM) of the left thalamus revealed tremor-synchronous grouped discharges with a vigorous (2.7 Hz) action tremor predominantly in the shoulder and upper arm. High frequency electrical stimulation in the VIM did not affect the tremor. A posteroventral pallidotomy (PVP) was performed and resulted in the successful alleviation of all tremor activity. Posteroventral pallidotomy is known to alleviate parkinsonian tremors, especially those occurring in the contralateral lower extremity, trunk, and proximal segment of the contralateral upper extremity. The authors consider the pallidoreticular pathway to be an important tremor-mediating pathway for the proximal segment of the upper extremities and believe it can be controlled more effectively by PVP than by VIM thalamotomy, as demonstrated by the PVP-induced resolution of the midbrain tremor observed in this case.

Sign in / Sign up

Export Citation Format

Share Document