Variable Damping and Stiffness Vibration Control With Two Magnetorheological Fluid Dampers in Series

2005 ◽  
Author(s):  
Yanqing Liu ◽  
Hiroshi Matsuhisa ◽  
Hideo Utsuno ◽  
Jeong Gyu Park
Keyword(s):  
Vibration Control ◽  
Vibration Isolation ◽  
Degree Of Freedom ◽  
Structural Vibration ◽  
Small Current ◽  
Mr Dampers ◽  
In Series ◽  
Variable Damping ◽  
Fluid Dampers ◽  
Two Degree Of Freedom

Vibration isolation methods that vary damping and stiffness have demonstrated excellent authority over system vibration, thus, potentially making them attractive for many applications. However, conventional devices for controlling variable stiffness are typically complicated and difficult to implement in most applications. To address this issue, a new method is proposed that requires two magnetorheological (MR) fluid dampers placed in series. With this configuration, variable damping and stiffness vibration control is simultaneously achieved by varying a small current to the MR dampers. This paper presents a theoretical and experimental analysis of a two degree-of-freedom system that is controlled by the MR dampers. Five different control schemes involving the variable damping and stiffness are explored. The time and frequency responses of the two degree-of-freedom system to a random input show that combined variable damping and stiffness control provides the best vibration isolation over a frequency range spanning the system’s two structural vibration modes. The experimental results agree well with the theoretical analysis.

Vibration Control of a New Bed Stage System for Ambulance Using MR Dampers

2014 ◽  
Author(s):  
Hee-Dong Chae ◽  
Seung-bok Choi ◽  
Jong-Seok Oh
Keyword(s):  
Mathematical Model ◽  
Vibration Control ◽  
Vibration Isolation ◽  
Design Parameters ◽  
Ride Quality ◽  
Vibration Level ◽  
Mr Dampers ◽  
Secondary Damage ◽  
Stage System ◽  
Magneto Rheological

This paper proposes a new bed stage for patients in ambulance vehicle in order to improve ride quality in term of vibration control. The vibration of patient compartment in ambulance can cause a secondary damage to a patient and a difficulty for a doctor to perform emergency care. The bed stage is to solve vertical, rolling, and pitching vibration in patient compartment of ambulance. Four MR (magneto-rheological) dampers are equipped for vibration isolation of the stage. Firstly, a mathematical model of stage is derived followed by the measurement of vibration level of patient compartment of real ambulance vehicle. Then, the design parameters of bed stage is undertaken via computer simulation. Skyhook, PID and LQR controllers are used for vibration control and their control performances are compared.

scholarly journals Application of Tuned Mass Dampers for Structural Vibration Control: A State-of-the-art Review

2020 ◽  
Vol 6 (8) ◽  
pp. 1622-1651
Author(s):  
Fatemeh Rahimi ◽  
Reza Aghayari ◽  
Bijan Samali
Keyword(s):  
Vibration Control ◽  
Control Systems ◽  
Performance Optimization ◽  
Structural Control ◽  
Vibration Isolation ◽  
Hybrid Control ◽  
Structural Vibration ◽  
Tuned Mass Dampers ◽  
Advantages And Disadvantages ◽  
Hybrid Control Systems

Given the burgeoning demand for construction of structures and high-rise buildings, controlling the structural vibrations under earthquake and other external dynamic forces seems more important than ever. Vibration control devices can be classified into passive, active and hybrid control systems. The technologies commonly adopted to control vibration, reduce damage, and generally improve the structural performance, include, but not limited to, damping, vibration isolation, control of excitation forces, vibration absorber. Tuned Mass Dampers (TMDs) have become a popular tool for protecting structures from unpredictable vibrations because of their relatively simple principles, their relatively easy performance optimization as shown in numerous recent successful applications. This paper presents a critical review of active, passive, semi-active and hybrid control systems of TMD used for preserving structures against forces induced by earthquake or wind, and provides a comparison of their efficiency, and comparative advantages and disadvantages. Despite the importance and recent advancement in this field, previous review studies have only focused on either passive or active TMDs. Hence this review covers the theoretical background of all types of TMDs and discusses the structural, analytical, practical differences and the economic aspects of their application in structural control. Moreover, this study identifies and highlights a range of knowledge gaps in the existing studies within this area of research. Among these research gaps, we identified that the current practices in determining the principle natural frequency of TMDs needs improvement. Furthermore, there is an increasing need for more complex methods of analysis for both TMD and structures that consider their nonlinear behavior as this can significantly improve the prediction of structural response and in turn, the optimization of TMDs.

scholarly journals Spatial Mechanism Design in Virtual Reality With Networking

2001 ◽  
Author(s):  
John N. Kihonge ◽  
Judy M. Vance ◽  
Pierre M. Larochelle
Keyword(s):  
Virtual Reality ◽  
Finite Sequence ◽  
Degree Of Freedom ◽  
Three Dimensions ◽  
Synthesis Process ◽  
Spatial Mechanisms ◽  
Cylindrical Joint ◽  
In Series ◽  
Simply Connected ◽  
Two Degree Of Freedom

Abstract Mechanisms are used in many devices to move a rigid body through a finite sequence of prescribed locations in space. The most commonly used mechanisms are four-bar planar mechanisms that move an object in one plane in space. Spatial mechanisms allow motion in three-dimensions (3D). Spatial 4C mechanisms are two degree of freedom kinematic closed-chains consisting of four rigid links simply connected in series by cylindrical (C) joints. A cylindrical joint is a two degree of freedom joint which allows translation along and rotation about a line in space. This paper describes a synthesis process for the design of 4C spatial mechanisms in a virtual environment. Virtual reality allows the user to view and interact with digital models in a more intuitive way than using the traditional human-computer interface (HCI). The software developed as part of this research also allows multiple users to network and share the designed mechanism. Networking tools have the potential to greatly enhance communication between members of the design team at different industrial sites and therefore reduce design costs.

Vibration Control of Two-Degree-of-Freedom Structures Utilizing Sloshing in Nearly Square Tanks

2017 ◽  
Vol 12 (5) ◽  
Author(s):  
Takashi Ikeda ◽  
Yuji Harata ◽  
Shota Ninomiya
Keyword(s):  
Vibration Control ◽  
Equations Of Motion ◽  
Excitation Frequency ◽  
Harmonic Excitation ◽  
Degree Of Freedom ◽  
Response Curves ◽  
Chaotic Motions ◽  
Installation Angle ◽  
Two Degree Of Freedom ◽  
Theoretical Results

This paper investigates the vibration control of a towerlike structure with degrees of freedom utilizing a square or nearly square tuned liquid damper (TLD) when the structure is subjected to horizontal, harmonic excitation. In the theoretical analysis, when the two natural frequencies of the two-degree-of-freedom (2DOF) structure nearly equal those of the two predominant sloshing modes, the tuning condition, 1:1:1:1, is nearly satisfied. Galerkin's method is used to derive the modal equations of motion for sloshing. The nonlinearity of the hydrodynamic force due to sloshing is considered in the equations of motion for the 2DOF structure. Linear viscous damping terms are incorporated into the modal equations to consider the damping effect of sloshing. Van der Pol's method is employed to determine the expressions for the frequency response curves. The influences of the excitation frequency, the tank installation angle, and the aspect ratio of the tank cross section on the response curves are examined. The theoretical results show that whirling motions and amplitude-modulated motions (AMMs), including chaotic motions, may occur in the structure because swirl motions and Hopf bifurcations, followed by AMMs, appear in the tank. It is also found that a square TLD works more effectively than a conventional rectangular TLD, and its performance is further improved when the tank width is slightly increased and the installation angle is equal to zero. Experiments were conducted in order to confirm the validity of the theoretical results.

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