scholarly journals Seismic Control of SDOF Systems with Nonlinear Eddy Current Dampers

2019 ◽  
Vol 9 (16) ◽  
pp. 3427 ◽  
Author(s):  
Longteng Liang ◽  
Zhouquan Feng ◽  
Zhengqing Chen
Keyword(s):  
Energy Dissipation ◽  
Eddy Current ◽  
Experimental Testing ◽  
Model Fitting ◽  
Good Alternative ◽  
Dynamic Responses ◽  
Control Performance ◽  
Seismic Control ◽  
Fluid Viscous Dampers ◽  
Nonlinear Force

The nonlinear model and energy dissipation of a rotary axial eddy current damper (ECD) and the dynamic responses to harmonic and seismic base excitations of a linear elastic SDOF system with the nonlinear ECD (SDOF-ECD) are investigated. Firstly, the nonlinear force-velocity relationship of the ECD is studied using finite element simulation, experimental testing and mathematical model fitting. Secondly, the energy dissipated by the nonlinear ECD under a cycle of harmonic motion is derived analytically and its optimal critical velocity is determined such that the energy dissipation is maximized. Finally, the responses of the SDOF-ECDs subjected to harmonic and seismic base excitations are calculated using numerical algorithm, where the displacement and acceleration control performance and the energy dissipation capacity of the ECD are compared with those of the conventional fluid viscous dampers (FVDs). The results indicate that the seismic control performance of ECDs outperforms that of FVDs in most cases and it is anticipated that the ECDs can be used as good alternative devices to conventional FVDs for seismic control applications.

Seismic Control of a Self-Anchored Suspension Bridge Using Fluid Viscous Dampers

2020 ◽  
pp. 2150025
Author(s):  
Dongming Feng ◽  
Jingquan Wang
Keyword(s):  
Energy Dissipation ◽  
Shear Force ◽  
Bending Moment ◽  
Suspension Bridge ◽  
Longitudinal Direction ◽  
Damping Coefficient ◽  
Suspension Bridges ◽  
Seismic Control ◽  
Fluid Viscous Dampers ◽  
Connection System

A self-anchored suspension bridge balances forces internally without external anchorage requirements, making it suitable for sites where anchorages would be difficult to construct. It often adopts either a full-floating or a semi-floating tower-girder connection system, which may result in large displacement responses along bridge longitudinal direction during earthquakes. This study investigated the efficacy of using the fluid viscous damper (FVD) for seismic control of a single-tower self-anchored suspension bridge. First, the energy dissipation behaviors of the FVD under sinusoidal excitations were studied. It revealed that besides the damper parameters (i.e. damping coefficient and velocity exponent) of an FVD itself, the energy dissipation capacity also relies on the characteristics of external excitations. Therefore, optimum damper parameters added to a structure should be determined on a case-by-case basis. Parametric study was then carried out on the prototype bridge, which indicated a tendency of decreasing the longitudinal deck/tower displacements and tower forces with increasing damping coefficient [Formula: see text] and decreasing velocity exponent [Formula: see text]. Compared with the linear FVD, the nonlinear FVD with a smaller velocity exponent can develop more rectangular force-displacement loops and thus achieve better energy dissipation performance. With selected optimum damper parameters (i.e. [Formula: see text][Formula: see text]kN[Formula: see text]m[Formula: see text][Formula: see text]s[Formula: see text] and [Formula: see text]) for the two FVDs added between the deck and the tower, the longitudinal deck and tower displacements could be reduced by 54%, while the peak bending moment and shear force at the tower base could be reduced by 30% and 19%, respectively. It is concluded that the nonlinear FVD can provide a simple and efficient solution to reduce displacement responses of self-anchored suspension bridges while simultaneously reducing the bending moment and shear force in the tower.

scholarly journals Fique as a Sustainable Material and Thermal Insulation for Buildings: Study of Its Decomposition and Thermal Conductivity

2021 ◽  
Vol 13 (13) ◽  
pp. 7484
Author(s):  
Gabriel Fernando García Sánchez ◽  
Rolando Enrique Guzmán López ◽  
Roberto Alonso Gonzalez-Lezcano
Keyword(s):  
Thermal Conductivity ◽  
Thermal Decomposition ◽  
Thermal Insulation ◽  
Model Fitting ◽  
Good Alternative ◽  
Negative Effects ◽  
Thermal Insulator ◽  
Fitting Method ◽  
Thermogravimetric Data ◽  
Reduce Energy Consumption

Buildings consume a large amount of energy during all stages of their life cycle. One of the most efficient ways to reduce their consumption is to use thermal insulation materials; however, these generally have negative effects on the environment and human health. Bio-insulations are presented as a good alternative solution to this problem, thus motivating the study of the properties of natural or recycled materials that could reduce energy consumption in buildings. Fique is a very important crop in Colombia. In order to contribute to our knowledge of the properties of its fibers as a thermal insulator, the measurement of its thermal conductivity is reported herein, employing equipment designed according to the ASTM C 177 standard and a kinetic study of its thermal decomposition from thermogravimetric data through the Coats–Redfern model-fitting method.

Experimental study on seismic control of towers in cable-supported bridges by incorporating fluid viscous dampers between sub-towers

2020 ◽  
Vol 23 (10) ◽  
pp. 2086-2096
Author(s):  
Peng Zhou ◽  
Min Liu ◽  
Suchao Li ◽  
Hui Li ◽  
Gangbing Song
Keyword(s):  
Control Strategies ◽  
Experimental Tests ◽  
Shaking Table ◽  
Viscous Dampers ◽  
Damping Force ◽  
Alternative Scheme ◽  
Seismic Control ◽  
Fluid Viscous Dampers ◽  
Seismic Loadings ◽  
Energy Dissipation Devices

In this article, the seismic control of towers incorporated with fluid viscous dampers between sub-towers is investigated experimentally. To replace one entire tower, an alternative scheme consisting of four separate sub-towers is first proposed. Fluid viscous dampers are utilized as energy dissipation devices to be installed between sub-towers. Experimental tests are conducted to study the damping force characteristics. Three control strategies with various distributions of these dampers between sub-towers are developed. Then, a series of shaking table tests are carried out to evaluate the control performance of the proposed control strategies. Different earthquake records are adopted as seismic loadings. Experimental results clearly show a remarkable reduction in the towers seismic responses, including the accelerations, relative displacements, and strains. Rather than attaching dampers in concentrated ways, the strategy of distributing dampers uniformly behaves better.

scholarly journals Editorial for Special Issue “Energy Dissipation and Vibration Control: Materials, Modeling, Algorithm, and Devices”

2020 ◽  
Vol 10 (2) ◽  
pp. 572 ◽  
Author(s):  
Gangbing Song ◽  
Hong-Nan Li ◽  
Steve C.S. Cai
Keyword(s):  
Energy Dissipation ◽  
Vibration Control ◽  
Active Vibration Control ◽  
Vibration Damping ◽  
Dynamic Responses ◽  
Special Issue ◽  
The Arts ◽  
Materials Modeling ◽  
Active Vibration ◽  
Energy Dissipation Devices

Many engineering systems, from subsea pipelines to space structures, from moving vehicles to stationary skyscrapers, are subject to unwanted vibration excitations. Often vibration control can be considered as a problem of energy dissipation and vibration damping. The aims of this issue are to accumulate, disseminate, and promote new knowledge about vibration control, especially for topics related to energy dissipation methods for vibration damping. Topics in this issue reflect the start-of-the-arts in the field of vibration control, such as inerter dampers and pounding tuned mass dampers (PTMDs). This special issue also reports other types of new energy dissipation devices, including a multi-unit particle damper, a nonlinear eddy current damper, and layered dampers. Also reported in this issue are structural elements with innovative designs to dissipate energy. In addition, this special issue also reports two research studies on the dynamic responses of a structural foundation and an earth-retaining structure. Though most papers in this special issue are related to passive methods, one paper reports a semi-active vibration control via magnetorheological dampers (MRDs), and another two papers report active vibration controls using piezoelectric transducers and inertial actuators, respectively.

The Use of Eddy Current Sensors for the Measurement of Rotor Blade Tip Timing: Development of a New Method Based on Integration

2016 ◽  
Author(s):  
K. S. Chana ◽  
V. Sridhar ◽  
D. Singh
Keyword(s):  
Gas Turbine ◽  
Eddy Current ◽  
Health Monitoring ◽  
Rotor Blade ◽  
Power Plants ◽  
Service Use ◽  
Low Cost ◽  
Good Alternative ◽  
Blade Vibration ◽  
Current Sensors

The advent of tip-timing systems makes it possible to assess turbomachinery blade vibration using non-contact systems. The most widely used systems in industry are optical. However, these systems are still only used on developmental gas turbine engines, largely because of contamination problems from dust, dirt, oil, water etc. Further development of these systems for in-service use is problematic because of the difficulty of eliminating contamination of the optics. Eddy current sensors are found to be a good alternative and are already being used for gas turbine health monitoring in power plants. Experimental measurements have been carried out on three different rotors using an eddy current sensor developed in a series of laboratory and engine tests in-house to measure rotor blade arrival times. A new tip-timing algorithm for eddy current sensors based on integration has been developed and is compared with two existing tip-timing algorithms: peak-to-peak and peak-and-trough. Among the three, the integration method provided the most promising results in the presence of electrical noise interference. The main aim of this work is to develop an algorithm that can be used to build a simple, robust, real-time and low cost analogue electronic circuit for use in-service health monitoring of engines.

scholarly journals Energy-Dissipation Performance of Combined Low Yield Point Steel Plate Damper Based on Topology Optimization and Its Application in Structural Control

2016 ◽  
Vol 2016 ◽  
pp. 1-16 ◽  
Author(s):  
Haoxiang He ◽  
Xiaobing Wang ◽  
Xiaofu Zhang
Keyword(s):  
Topology Optimization ◽  
Energy Dissipation ◽  
Yield Stress ◽  
Yield Point ◽  
Structural Control ◽  
Steel Plate ◽  
Steel Plates ◽  
Dynamic Responses ◽  
Initial Stiffness ◽  
Seismic Capacity

In view of the disadvantages such as higher yield stress and inadequate adjustability, a combined low yield point steel plate damper involving low yield point steel plates and common steel plates is proposed. Three types of combined plate dampers with new hollow shapes are proposed, and the specific forms include interior hollow, boundary hollow, and ellipse hollow. The “maximum stiffness” and “full stress state” are used as the optimization objectives, and the topology optimization of different hollow forms by alternating optimization method is to obtain the optimal shape. Various combined steel plate dampers are calculated by finite element simulation, the results indicate that the initial stiffness of the boundary optimized damper and interior optimized damper is lager, the hysteresis curves are full, and there is no stress concentration. These two types of optimization models made in different materials rations are studied by numerical simulation, and the adjustability of yield stress of these combined dampers is verified. The nonlinear dynamic responses, seismic capacity, and damping effect of steel frame structures with different combined dampers are analyzed. The results show that the boundary optimized damper has better energy-dissipation capacity and is suitable for engineering application.

A Modified Pall-Typed Friction Damper for Vibration Control in Series Compensation Platform Structure

2013 ◽  
Vol 405-408 ◽  
pp. 633-637
Author(s):  
Wen Hui Wei ◽  
Lai Gan ◽  
Meng Fei Hu ◽  
Jian Wang
Keyword(s):  
Passive Control ◽  
Wave Train ◽  
Time History ◽  
Internal Force ◽  
Dynamic Responses ◽  
Friction Damper ◽  
Series Compensation ◽  
Friction Dampers ◽  
Seismic Control ◽  
In Series

Based on the characteristics of series compensation platform structure, a method of installing modified Pall-typed friction dampers for seismic passive control was proposed. Compared with the conventional , the modified Pall-typed friction damper has the same effect on energy dissipation, and it is superior in imposing pretension at both ends and saving friction materials. The equations of relation between brace displacement and internal force of the modified Pall-typed friction damper were derived. Besides, the time-history analysis method for seismic responses of series compensation platform structures with modified Pall-typed friction dampers was established, and a sine amplitude-modulation wave train was applied to analyzing the dynamic responses of these structures. The results show that, the displacement of the series compensation platform structures with modified Pall-typed friction dampers decrease to some extent. The seismic control is effective.

scholarly journals Vibration suppression for high speed railway bridges using fluid viscous dampers

2019 ◽  
Vol 286 ◽  
pp. 01002
Author(s):  
M. Tahiri ◽  
A. Khamlichi ◽  
M. Bezzazi
Keyword(s):  
Structural Control ◽  
High Speed ◽  
Vibration Suppression ◽  
Dynamic Responses ◽  
Resonance Phenomenon ◽  
Bottom Surface ◽  
Viscous Dampers ◽  
Railway Bridges ◽  
Fluid Viscous Dampers ◽  
Promising Solution

The results of experimental and theoritical investigations of railway bridges have shown the significant dynamic responses exceeding that anticipated on certain railway bridges, such as a resonance phenomenon who have a great effect in the bridge. Alternatively , the use of structural control systems devices might be a very promising solution to attenuate undesirable vibration. The aim of this study, first, is to investigate the posibility of reducing the acceleration in an acceptable level by using fluid viscous dampers. The bridge-damper system is described by a single-degree-of-freedom model. The ,dampers are connected between the bottom surface of the bridge deck and the abutment, Finallay a linearisation model and a comparative study in order to investigate the effect of the nonlinearite of the device in the dynamic response of the system.

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