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You searched for subject:(magneto rheological dampers). Showing records 1 – 3 of 3 total matches.

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Michigan Technological University

1. Winter, Benjamin. Limited Bandwidth Wireless Communication Strategies for Structural Control of Seismically Excited Shear Structures.

Degree: PhD, Department of Civil and Environmental Engineering, 2017, Michigan Technological University

Structural control is used to mitigate unwanted vibrations in structures when large excitations occur, such as high winds and earthquakes. To increase reliability and controllability in structural control applications, engineers are making use of semi-active control devices. Semi-active control gives engineers greater control authority over structural response versus passive controllers, but are less expensive and more reliable than active devices. However, the large numbers of actuators required for semi-active structural control networks introduce more cabling within control systems leading to increased cost. Researchers are exploring the use of wireless technology for structural control to cut down on the installation cost associated with cabling. However wireless communication latency (time delays in data transmissions) can be a barrier to full acceptance of wireless technology for structural control. As the number of sensors in a control network grows, it becomes increasingly difficult to transmit all sensor data during a single control step over the fixed wireless bandwidth. Because control force calculations rely on accurate state measurements or estimates, the use of strategic bandwidth allocation becomes more necessary to provide good control performance. The traditional method for speeding up the control step in larger wireless networks is to spatially decentralize the network into multiple subnetworks, sacrificing communication for speed. This dissertation seeks to provide an additional approach to address the issue of communication latency that may be an alternative, or even a supplement, to spatial decentralization of the control network. The proposed approach is to use temporal decentralization, or the decentralization of the control network over time, as opposed to space/location. Temporal decentralization is first presented with a means of selecting and evaluating different communication group sizes and wireless unit combinations for staggered temporal group communication that still provide highly accurate state estimates. It is found that, in staggered communication schemes, state estimation and control performance are affected by the network topology used at each time step with some sensor combinations providing more useful information than others. Sensor placement theory is used to form sensor groups that provide consistently high-quality output information to the network during each time step, but still utilize all sensors. If the demand for sensors to communicate data outweighs the available bandwidth, traditional temporal and spatial approaches are no longer feasible. This dissertation examines and validates a dynamic approach for bandwidth allocation relying on an extended, autonomous and controller-aware, carrier sense multiple access with collision detection (CSMA/CD) protocol. Stochastic parameters are derived to strategically alter back-off times in the CSMA/CD algorithm based on nodal observability and output estimation error. Inspired by data fusion approaches,… Advisors/Committee Members: R. Andrew Swartz.

Subjects/Keywords: Wireless Structural Control; Semi-Active Control; LQG Control; Sensor Placement Theory; Temporal Decentralization; Magneto-Rheological Dampers; Structural Engineering

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APA (6th Edition):

Winter, B. (2017). Limited Bandwidth Wireless Communication Strategies for Structural Control of Seismically Excited Shear Structures. (Doctoral Dissertation). Michigan Technological University. Retrieved from https://digitalcommons.mtu.edu/etdr/392

Chicago Manual of Style (16th Edition):

Winter, Benjamin. “Limited Bandwidth Wireless Communication Strategies for Structural Control of Seismically Excited Shear Structures.” 2017. Doctoral Dissertation, Michigan Technological University. Accessed January 24, 2021. https://digitalcommons.mtu.edu/etdr/392.

MLA Handbook (7th Edition):

Winter, Benjamin. “Limited Bandwidth Wireless Communication Strategies for Structural Control of Seismically Excited Shear Structures.” 2017. Web. 24 Jan 2021.

Vancouver:

Winter B. Limited Bandwidth Wireless Communication Strategies for Structural Control of Seismically Excited Shear Structures. [Internet] [Doctoral dissertation]. Michigan Technological University; 2017. [cited 2021 Jan 24]. Available from: https://digitalcommons.mtu.edu/etdr/392.

Council of Science Editors:

Winter B. Limited Bandwidth Wireless Communication Strategies for Structural Control of Seismically Excited Shear Structures. [Doctoral Dissertation]. Michigan Technological University; 2017. Available from: https://digitalcommons.mtu.edu/etdr/392


Virginia Tech

2. El-Aouar, Walid Hassib. Finite Element Analysis Based Modeling of Magneto Rheological Dampers.

Degree: MS, Mechanical Engineering, 2002, Virginia Tech

A Finite Element model was built to analyze and examine a 2-D axisymmetric MR damper. This model has been validated with the experimental data. The results obtained in this thesis will help designers to create more efficient and reliable MR dampers. We can create some design analysis to change the shape of the piston in the damper or other parameters in the model. The main benefit of this research is to show a 2-D MR damper and generate the magnetic flux density along the MR Fluid gap. We can detect saturation by looking at the nodal solution for the magnetic flux density. Increasing the current in the model, results in an increase in magnetic induction. We studied four different configurations of an MR damper piston in order to determine how changing the shape of the piston affects the maximum force that the damper can provide. In designing MR dampers, the designer always faces the challenge of providing the largest forces in the most compact and efficient envelope. Therefore, it is important to identify the configuration that gives more force in less space. In chapter 4, shows the magnetic flux density contour before and after reaching the rheological saturation. By increasing the current, the color spectrum of the magnetic flux density will shift from the MR fluid gap to the piston centerline. In chapter 5, we provided a reasonably good amount of force in model 4 at 1.4 Amps, but it reaches saturation before the other models. For cases with power constraint or heat build up limitations, this model could work the best among the four designs that we considered. For cases where higher electrical currents can be tolerated, model 3 would be the most advantageous design, since it provides the largest force among the four models. Advisors/Committee Members: Ahmadian, Mehdi (committeechair), Leo, Donald J. (committee member), Inman, Daniel J. (committee member).

Subjects/Keywords: force provided; modeling magneto rheological dampers; magnetic flux density; magnetic flux line; Magnetic field

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

El-Aouar, W. H. (2002). Finite Element Analysis Based Modeling of Magneto Rheological Dampers. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/35165

Chicago Manual of Style (16th Edition):

El-Aouar, Walid Hassib. “Finite Element Analysis Based Modeling of Magneto Rheological Dampers.” 2002. Masters Thesis, Virginia Tech. Accessed January 24, 2021. http://hdl.handle.net/10919/35165.

MLA Handbook (7th Edition):

El-Aouar, Walid Hassib. “Finite Element Analysis Based Modeling of Magneto Rheological Dampers.” 2002. Web. 24 Jan 2021.

Vancouver:

El-Aouar WH. Finite Element Analysis Based Modeling of Magneto Rheological Dampers. [Internet] [Masters thesis]. Virginia Tech; 2002. [cited 2021 Jan 24]. Available from: http://hdl.handle.net/10919/35165.

Council of Science Editors:

El-Aouar WH. Finite Element Analysis Based Modeling of Magneto Rheological Dampers. [Masters Thesis]. Virginia Tech; 2002. Available from: http://hdl.handle.net/10919/35165


University of Southern California

3. Yun, Hae-Bum. Analytical and experimental studies of modeling and monitoring uncertain nonlinear systems.

Degree: PhD, Civil Engineering (Structural Mechanics), 2007, University of Southern California

The development of effective structural health monitoring (SHM) methodologies is imperative for the efficient maintenance of important structures in aerospace, mechanical and civil engineering. Based on reliable condition assessment, the owners of monitored structures can expect two important benefits: to avoid catastrophic accidents by detecting various types of structural deterioration during operation, and to establish efficient maintenance means and time schedule to reduce maintenance costs.; A vibration-based SHM methodology is evaluated for change detection in nonlinear systems that can be frequently seen in many engineering fields. The proposed methodology is advantageous over existing SHM methodologies regarding the following aspects: feasible to detect small changes in complex nonlinear systems, possible to make physical interpretation of detected changes, and possible to quantify the uncertainty associated with the change detection.; A series of analytical and experimental studies was performed to investigate various important issues in modeling and monitoring of uncertain nonlinear systems. Different parametric and non-parametric identification methods were compared for monitoring purpose using full-scale nonlinear viscous dampers for seismic mitigation in civil structures. Then, the effects of uncertainty on change detection performance were investigated. Two types of uncertainty were studied: measurement uncertainty and system characteristic uncertainty. For measurement uncertainty, three different types of full-scale nonlinear viscous dampers were used to validate the proposed SHM methodology when the dampers' response was polluted with random noise. For system characteristic uncertainty, a semi-active magneto-rheological damper whose system characteristics were determined through user controllable input current was used. Statistical pattern recognition methods were studied to detect relatively small changes in nonlinear systems with different uncertainty types. The Bootstrap method, a statistical data resampling technique, was also studied to estimate the uncertainty bounds of change detection when the measurement data are insufficient for reliable statistical inference.; A web-based real-time bridge monitoring system was developed and used for a forensic study involving a cargo ship collision with the Vincent Thomas Bridge, a critical suspension bridge in the metropolitan Los Angeles region. Advisors/Committee Members: Sami F. Masri (Committee Chair), Carter Wellford (Committee Member), Jiin-Jen Lee (Committee Member), John P. Caffrey (Committee Member), Roger G. Ghanem (Committee Member).

Subjects/Keywords: structural health monitoring; system identification; Restoring Force Method; artificial neural networks; Hypothesis Test; Bootstrap Method; statistical pattern recognition; support vector machines; k-means clustering; error analysis; detection theory; Natural Excitation Technique; Eigensystem Realization Algorithm; full-scale viscous dampers; magneto-rheological dampers; suspension bridge; web-based real-time bridge monitoring system; ship-bridge collision

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Yun, H. (2007). Analytical and experimental studies of modeling and monitoring uncertain nonlinear systems. (Doctoral Dissertation). University of Southern California. Retrieved from http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll127/id/528810/rec/819

Chicago Manual of Style (16th Edition):

Yun, Hae-Bum. “Analytical and experimental studies of modeling and monitoring uncertain nonlinear systems.” 2007. Doctoral Dissertation, University of Southern California. Accessed January 24, 2021. http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll127/id/528810/rec/819.

MLA Handbook (7th Edition):

Yun, Hae-Bum. “Analytical and experimental studies of modeling and monitoring uncertain nonlinear systems.” 2007. Web. 24 Jan 2021.

Vancouver:

Yun H. Analytical and experimental studies of modeling and monitoring uncertain nonlinear systems. [Internet] [Doctoral dissertation]. University of Southern California; 2007. [cited 2021 Jan 24]. Available from: http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll127/id/528810/rec/819.

Council of Science Editors:

Yun H. Analytical and experimental studies of modeling and monitoring uncertain nonlinear systems. [Doctoral Dissertation]. University of Southern California; 2007. Available from: http://digitallibrary.usc.edu/cdm/compoundobject/collection/p15799coll127/id/528810/rec/819

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