subject:(vibration control)

Northeastern University

1. Sidoti, Charles. Active vibration control of a flexible plate system.

Degree: MS, Department of Mechanical and Industrial Engineering, 2013, Northeastern University

URL: http://hdl.handle.net/2047/d20003380

► Vibration control and/or attenuation can significantly improve the performance and operation of systems and machines in various industries. As technology advances, the methods of vibration… (more)

▼ Vibration control and/or attenuation can significantly improve the performance and operation of systems and machines in various industries. As technology advances, the methods of vibration control also become more involved and therefore allow for control of more complex structures. This thesis focuses on vibration control of a flexible plate system. The basic modeling of the physical system is developed as a precursor to the controller design. Linear controllers are explored along with advanced controllers. These controllers require an accurate model of the physical system of interest. For this reason, an experimental setup is designed and developed for implementation. A major part of this thesis is devoted to the experimental design, setup, and implementation of different controllers to achieve broadband attenuation within a frequency range from 400 to 2000 Hz.; An experimental setup is designed to demonstrate attenuation of flexible modes of the plate system. Actuators, accelerometers, and force sensors are specified to apply appropriate disturbance forces of varying complexity and to measure and record data necessary to update the theoretical model and design an effective controller. The experimental setup is initially made up of three relatively large stacked aluminum plates. After proof-of-concept results are obtained, the setup is scaled down to represent a more applicable system. The miniaturized setup is made up of a large base plate to distribute the input forces and a small flexible plate to be controlled. The control scheme involves non-collocation control of a location to which the accelerometer is mounted. With a desired range of attenuation, the controller is designed and developed. The initial stages involve experimental development of a PID controller using time delays and filters to attenuate multiple resonant frequencies. The controller showed 58% and 81% attenuations of the first two resonant peaks at 618 Hz and 1001 Hz, respectively. These results represent a proof-of-concept using the measured force input as feedback to the controller. In parallel, a model reference adaptive controller is explored, and data is recorded for later use in updating the model for increased accuracy. Significantly greater attenuation is envisioned with the completion of the development of this advanced controller.

Subjects/Keywords: Active Control; Vibration; Vibration Control; Mechanical Engineering

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APA (6^th Edition):

Sidoti, C. (2013). Active vibration control of a flexible plate system. (Masters Thesis). Northeastern University. Retrieved from http://hdl.handle.net/2047/d20003380

Chicago Manual of Style (16^th Edition):

Sidoti, Charles. “Active vibration control of a flexible plate system.” 2013. Masters Thesis, Northeastern University. Accessed March 03, 2021. http://hdl.handle.net/2047/d20003380.

MLA Handbook (7^th Edition):

Sidoti, Charles. “Active vibration control of a flexible plate system.” 2013. Web. 03 Mar 2021.

Vancouver:

Sidoti C. Active vibration control of a flexible plate system. [Internet] [Masters thesis]. Northeastern University; 2013. [cited 2021 Mar 03]. Available from: http://hdl.handle.net/2047/d20003380.

Council of Science Editors:

Sidoti C. Active vibration control of a flexible plate system. [Masters Thesis]. Northeastern University; 2013. Available from: http://hdl.handle.net/2047/d20003380

2. Thomas, Rohan. Prediction Of Aircraft Fuselage Vibration.

Degree: MEngr, Mechanical Engineering, 2015, University of North Dakota

URL: https://commons.und.edu/theses/1844

► Modern unmanned aerial vehicles (UAV) are made of lightweight structures, owing to the demand for longer ranges and heavier payloads. These lightweight aircraft are… (more)

▼ Modern unmanned aerial vehicles (UAV) are made of lightweight structures, owing to the demand for longer ranges and heavier payloads. These lightweight aircraft are more susceptible to vibrations caused by atmospheric turbulence transmitted to the fuselage from the wings. These vibrations, which can cause damage to the payload or on board avionics present a serious problem, since air turbulence is expected to increase over the next few decades, due to climate change. The objective of this thesis is to predict the vibration of an aircraft fuselage by establishing a relationship between wing and fuselage vibration. A combination of ANSYSÂ® and MATLABÂ® modeling are used to simulate aircraft vibrations. First, the displacement of a lumped mass aircraft model to step and sinusoidal forces acting on the wings are compared to displacements calculated using modal superposition equations. Next, a state space representation of this system is found using system identification techniques, which uses wing displacement as input, and provides fuselage displacement as output. This state space model is compared to a derived state space model for validation. Finally, a three dimensional aircraft with distributed displacement sensors on its wings is modeled. A state space representation is established using the wing displacement output from the sensors as its input and the motion and rotation of the fuselage along the X, Y and Z axes as the output. It is seen that the displacement results of the lumped mass system match with those calculated using modal superposition equations. The state space model can also accurately predict the fuselage vibration of the lumped mass system, when provided with wing displacement as input. More importantly, results have shown that the distributed vibration sensors on the three dimensional plane model are able to measure the wing displacements. Using the output from these distributed sensors, the motion and rotation of the fuselage about all three axes can be effectively predicted. Advisors/Committee Members: Marcellin Zahui.

Subjects/Keywords: Piezoelectric; PVDF; Turbulence; UAV; Vibration; Vibration Control

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APA (6^th Edition):

Thomas, R. (2015). Prediction Of Aircraft Fuselage Vibration. (Masters Thesis). University of North Dakota. Retrieved from https://commons.und.edu/theses/1844

Chicago Manual of Style (16^th Edition):

Thomas, Rohan. “Prediction Of Aircraft Fuselage Vibration.” 2015. Masters Thesis, University of North Dakota. Accessed March 03, 2021. https://commons.und.edu/theses/1844.

MLA Handbook (7^th Edition):

Thomas, Rohan. “Prediction Of Aircraft Fuselage Vibration.” 2015. Web. 03 Mar 2021.

Vancouver:

Thomas R. Prediction Of Aircraft Fuselage Vibration. [Internet] [Masters thesis]. University of North Dakota; 2015. [cited 2021 Mar 03]. Available from: https://commons.und.edu/theses/1844.

Council of Science Editors:

Thomas R. Prediction Of Aircraft Fuselage Vibration. [Masters Thesis]. University of North Dakota; 2015. Available from: https://commons.und.edu/theses/1844

Penn State University

3. Austruy, Julien. ROTOR HUB VIBRATION AND BLADE LOADS REDUCTION, AND ENERGY HARVESTING VIA EMBEDDED RADIAL OSCILLATOR .

Degree: 2011, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/12121

► An embedded radial absorber is investigated to control helicopter rotor hub vibration and blade loads. The absorber is modeled as a discrete mass moving in… (more)

▼ An embedded radial absorber is investigated to control helicopter rotor hub vibration and blade loads. The absorber is modeled as a discrete mass moving in the spanwise direction within the blade. The absorber is retained in place and tuned with a spring and a damper. The radial absorber couples with lead-lag dynamic through Coriolis forces. The embedded radial absorber coupled to the helicopter is analyzed with a comprehensive rotorcraft model. The blade is modeled as an elastic beam undergoing flap bending, lag bending and elastic torsion, and a radial degree of freedom is added for the absorber. The tuning of the embedded radial absorber to a frequency close to 3/rev with no damping is shown to reduce significantly (up to 86%) the 4/rev in-plane hub forces of a 4-bladed hingeless rotor similar to a MBB BO-105 in high speed flight. The simulation shows that the absorber modifies the in-plane blade root shears to synchronize them to cancel each other in the transmission from rotating frame to fixed frame. A design of an embedded radial absorber experiment for hub vibration control is presented and it is concluded that for such high tuning frequencies as 3/rev, it is feasible to use a regular coil spring to compensate for the steady centrifugal force. Large reduction of blade lag shear (85%) and lag bending moment (71%) is achieved by tuning the embedded radial absorber close to 1/rev (also shown for a BO-105 like helicopter in high speed flight). The absorber reduces the amplitude of the lag bending moment at 1/rev, thus reducing the blade lead-lag motion and reducing the blade drag shear and lag bending moment. Finally, the use of the embedded radial absorber is investigated as a source electrical power when combined with an electromagnetic circuit. A model of the electromagnetic system is developed and validated, and an evaluation of the amount of power harvestable for different configurations is presented. The maximum power harvested was calculated to be 133 watts. Advisors/Committee Members: Dr Farhan Gandhi, Dissertation Advisor/Co-Advisor, Farhan S Gandhi, Committee Chair/Co-Chair, George A Lesieutre, Committee Member, Edward C Smith, Committee Member, Sean N Brennan, Committee Member, Karl Martin Reichard, Committee Member.

Subjects/Keywords: vibration control; rotorcraft; energy harvesting

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APA (6^th Edition):

Austruy, J. (2011). ROTOR HUB VIBRATION AND BLADE LOADS REDUCTION, AND ENERGY HARVESTING VIA EMBEDDED RADIAL OSCILLATOR . (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/12121

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Austruy, Julien. “ROTOR HUB VIBRATION AND BLADE LOADS REDUCTION, AND ENERGY HARVESTING VIA EMBEDDED RADIAL OSCILLATOR .” 2011. Thesis, Penn State University. Accessed March 03, 2021. https://submit-etda.libraries.psu.edu/catalog/12121.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Austruy, Julien. “ROTOR HUB VIBRATION AND BLADE LOADS REDUCTION, AND ENERGY HARVESTING VIA EMBEDDED RADIAL OSCILLATOR .” 2011. Web. 03 Mar 2021.

Vancouver:

Austruy J. ROTOR HUB VIBRATION AND BLADE LOADS REDUCTION, AND ENERGY HARVESTING VIA EMBEDDED RADIAL OSCILLATOR . [Internet] [Thesis]. Penn State University; 2011. [cited 2021 Mar 03]. Available from: https://submit-etda.libraries.psu.edu/catalog/12121.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Austruy J. ROTOR HUB VIBRATION AND BLADE LOADS REDUCTION, AND ENERGY HARVESTING VIA EMBEDDED RADIAL OSCILLATOR . [Thesis]. Penn State University; 2011. Available from: https://submit-etda.libraries.psu.edu/catalog/12121

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Loughborough University

4. Majeed, Fesmi Abdul. Analysis and control of rotary drilling rigs.

Degree: PhD, 2013, Loughborough University

URL: http://hdl.handle.net/2134/12559

► The objective of this research is to analyze and develop controller to minimize vibrations of the drill string in rotary drilling rigs. The rotary drilling… (more)

▼ The objective of this research is to analyze and develop controller to minimize vibrations of the drill string in rotary drilling rigs. The rotary drilling process is affected by many vibrations which adversely affect the drilling efficiency. The vibrations are mainly classified into three: lateral, tosional and axial. Among the vibrations, lateral vibrations are the most destructive. The research conducted a detailed analysis on lateral vibrations. Bent drill string and unbalanced drill bit was found to be its major causes; and the resultant phenomenon was known as drill bit whirl. Practical demonstration and analysis of the bit whirl phenomenon was done by conducting experiments using an unbalanced drill bit model. Their controllability issues were also discussed and practical solutions suggested. Black box identification methods were applied to develop mathematical models for the system. Box Jenkins structure model was identified and validated by a twofold procedure. Accurate simulations results were obtained with a mere 0.05% residual. Studies revealed that the vibrations in rotary drilling were aggravated by two major causes: borehole friction and critical operation speeds. This research developed a self tuning adaptive controller which could effectively mitigate the vibration aggravating causes and improve overall drilling efficiency. On practical implementation, the controller automatically detected vibrations, mitigated the vibration aggravating causes, and resumed normal drilling operation in less than 10 seconds. The controller action was proven experimentally in two cases: (1) when affected by borehole friction and (2) in presence of an unbalanced drill bit. All the experiments and control techniques applied in this research are validated by experimental data. The prototype used in this research is also distinguished from the rest due to a universal joint, providing an additional two degrees of freedom. Thus, the laboratory set-up provided better dynamic analysis.

Subjects/Keywords: 622; Drilling; Rotary; Control; Vibration

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APA (6^th Edition):

Majeed, F. A. (2013). Analysis and control of rotary drilling rigs. (Doctoral Dissertation). Loughborough University. Retrieved from http://hdl.handle.net/2134/12559

Chicago Manual of Style (16^th Edition):

Majeed, Fesmi Abdul. “Analysis and control of rotary drilling rigs.” 2013. Doctoral Dissertation, Loughborough University. Accessed March 03, 2021. http://hdl.handle.net/2134/12559.

MLA Handbook (7^th Edition):

Majeed, Fesmi Abdul. “Analysis and control of rotary drilling rigs.” 2013. Web. 03 Mar 2021.

Vancouver:

Majeed FA. Analysis and control of rotary drilling rigs. [Internet] [Doctoral dissertation]. Loughborough University; 2013. [cited 2021 Mar 03]. Available from: http://hdl.handle.net/2134/12559.

Council of Science Editors:

Majeed FA. Analysis and control of rotary drilling rigs. [Doctoral Dissertation]. Loughborough University; 2013. Available from: http://hdl.handle.net/2134/12559

Delft University of Technology

5. Noodelijk, Reinoudt (author). High-precision control for Constant Distance Scanning Electrochemical Microscopy.

Degree: 2017, Delft University of Technology

URL: http://resolver.tudelft.nl/uuid:371d0292-51ba-4b94-b1b0-adb355af23b0

► This Report covers the initial research into modeling the Scanning Electrochemical Microscopy (SECM) system for the purposes of high precision control. The SECM system is… (more)

Subjects/Keywords: SECM; Modeling; Control; vibration; damping

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APA (6^th Edition):

Noodelijk, R. (. (2017). High-precision control for Constant Distance Scanning Electrochemical Microscopy. (Masters Thesis). Delft University of Technology. Retrieved from http://resolver.tudelft.nl/uuid:371d0292-51ba-4b94-b1b0-adb355af23b0

Chicago Manual of Style (16^th Edition):

Noodelijk, Reinoudt (author). “High-precision control for Constant Distance Scanning Electrochemical Microscopy.” 2017. Masters Thesis, Delft University of Technology. Accessed March 03, 2021. http://resolver.tudelft.nl/uuid:371d0292-51ba-4b94-b1b0-adb355af23b0.

MLA Handbook (7^th Edition):

Noodelijk, Reinoudt (author). “High-precision control for Constant Distance Scanning Electrochemical Microscopy.” 2017. Web. 03 Mar 2021.

Vancouver:

Noodelijk R(. High-precision control for Constant Distance Scanning Electrochemical Microscopy. [Internet] [Masters thesis]. Delft University of Technology; 2017. [cited 2021 Mar 03]. Available from: http://resolver.tudelft.nl/uuid:371d0292-51ba-4b94-b1b0-adb355af23b0.

Council of Science Editors:

Noodelijk R(. High-precision control for Constant Distance Scanning Electrochemical Microscopy. [Masters Thesis]. Delft University of Technology; 2017. Available from: http://resolver.tudelft.nl/uuid:371d0292-51ba-4b94-b1b0-adb355af23b0

University of Waterloo

6. Rushton, Mitchell. Vibration Control in Cable Robots Using a Multi-Axis Reaction System.

Degree: 2016, University of Waterloo

URL: http://hdl.handle.net/10012/10945

► The primary motivation of this thesis is to develop a control strategy for eliminating persistent vibrations in all six spatial directions of the end effector… (more)

Subjects/Keywords: robotics; control; vibration; cable-driven

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APA (6^th Edition):

Rushton, M. (2016). Vibration Control in Cable Robots Using a Multi-Axis Reaction System. (Thesis). University of Waterloo. Retrieved from http://hdl.handle.net/10012/10945

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Rushton, Mitchell. “Vibration Control in Cable Robots Using a Multi-Axis Reaction System.” 2016. Thesis, University of Waterloo. Accessed March 03, 2021. http://hdl.handle.net/10012/10945.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Rushton, Mitchell. “Vibration Control in Cable Robots Using a Multi-Axis Reaction System.” 2016. Web. 03 Mar 2021.

Vancouver:

Rushton M. Vibration Control in Cable Robots Using a Multi-Axis Reaction System. [Internet] [Thesis]. University of Waterloo; 2016. [cited 2021 Mar 03]. Available from: http://hdl.handle.net/10012/10945.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Rushton M. Vibration Control in Cable Robots Using a Multi-Axis Reaction System. [Thesis]. University of Waterloo; 2016. Available from: http://hdl.handle.net/10012/10945

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

7. 菅野, 秀. 多重構造音響連成場の振動解析制御 : Sound Insulation Control of a Multiple-wall Structure.

Degree: 2016, Tokyo Metropolitan University / 首都大学東京

URL: http://hdl.handle.net/10748/5587

►

This paper is concerned with active vibration control of a multiple-wall structure. A multiple-wall structure is composed of more than two uniformed panels separated by… (more)

Subjects/Keywords: Vibration Control; Vibration Isolation; Coupled Vibration

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APA (6^th Edition):

菅野, �. (2016). 多重構造音響連成場の振動解析制御 : Sound Insulation Control of a Multiple-wall Structure. (Thesis). Tokyo Metropolitan University / 首都大学東京. Retrieved from http://hdl.handle.net/10748/5587

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

菅野, 秀. “多重構造音響連成場の振動解析制御 : Sound Insulation Control of a Multiple-wall Structure.” 2016. Thesis, Tokyo Metropolitan University / 首都大学東京. Accessed March 03, 2021. http://hdl.handle.net/10748/5587.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

菅野, 秀. “多重構造音響連成場の振動解析制御 : Sound Insulation Control of a Multiple-wall Structure.” 2016. Web. 03 Mar 2021.

Vancouver:

菅野 �. 多重構造音響連成場の振動解析制御 : Sound Insulation Control of a Multiple-wall Structure. [Internet] [Thesis]. Tokyo Metropolitan University / 首都大学東京; 2016. [cited 2021 Mar 03]. Available from: http://hdl.handle.net/10748/5587.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

菅野 �. 多重構造音響連成場の振動解析制御 : Sound Insulation Control of a Multiple-wall Structure. [Thesis]. Tokyo Metropolitan University / 首都大学東京; 2016. Available from: http://hdl.handle.net/10748/5587

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Michigan

8. Reichl, Katherine. Active Metastructures for Light-Weight Vibration Suppression.

Degree: PhD, Aerospace Engineering, 2018, University of Michigan

URL: http://hdl.handle.net/2027.42/144044

► The primary objective of this work is to examine the effectiveness of metastructures for vibration suppression from a weight standpoint. Metastructures, a metamaterial inspired concept,… (more)

▼ The primary objective of this work is to examine the effectiveness of metastructures for vibration suppression from a weight standpoint. Metastructures, a metamaterial inspired concept, are structures with distributed vibration absorbers. In automotive and aerospace industries, it is critical to have low levels of vibrations while also using lightweight materials. Previous work has shown that metastructures are effective at mitigating vibrations but does not consider the effects of mass. This work considers mass by comparing a metastructure to a baseline structure of equal mass with no absorbers. The metastructures are characterized by the number of vibration absorbers, the mass ratio, and the natural frequencies of the vibration absorbers. The metastructure and baseline structure are modeled using a lumped mass model and a distributed mass model. The lumped mass model allows for mass and stiffness parameters to be varied independently without the need to consider geometry constraints. The distributed mass model is a more realistic representation of a physical structure and uses relevant material properties. The steady-state and transient time responses of the structure are obtained. The results of these models examine how the performance of the structure varies with respect to the number of vibration absorbers and the mass ratio. Additionally, the stiffness and mass distributions of the vibration absorbers are considered. When the ratio of stiffness over mass varies linearly, the absorbers create broad-band suppression. Overall, these results show it is possible to obtain a favorable vibration response without adding additional mass to the structure. The distributed vibration absorbers are realized through geometry modifications on the centimeter scale. To obtain the complex geometry needed for these structures, the metastructures are typically manufactured using 3D printers, specifically the Objet Connex 3D printer. To better understand the damping properties of the materials used by the Objet Connex, the viscoelastic properties are characterized. These properties are characterized by measuring the frequency and temperature dependent complex modulus values using a dynamic mechanical analysis (DMA) machine. The material properties are incorporated into the Golla-Hughes-McTavish (GHM) model to capture the damping effect. Using the time-temperature equivalence, the material properties are transformed to various temperatures, allowing the response of the structures to be modeled at various temperatures. A 3D printed metastructure is experimentally tested and compared to the GHM model. These results show the GHM model can accurately predict the natural frequencies of the vibration absorbers. Lastly, the concept of adding active vibration control to a metastructure to get additional vibration suppression is explored. This is done by attaching piezoelectric materials to the metastructure and utilizing the positive position feedback (PPF) control law to further reduce vibrations. Two active vibration absorber designs… Advisors/Committee Members: Inman, Daniel J (committee member), Lynch, Jerome P (committee member), Sodano, Henry (committee member), Sundararaghavan, Veera (committee member).

Subjects/Keywords: vibration suppression; viscoelastic materials; vibration absorbers; active vibration control; metastructures; Aerospace Engineering; Engineering

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APA (6^th Edition):

Reichl, K. (2018). Active Metastructures for Light-Weight Vibration Suppression. (Doctoral Dissertation). University of Michigan. Retrieved from http://hdl.handle.net/2027.42/144044

Chicago Manual of Style (16^th Edition):

Reichl, Katherine. “Active Metastructures for Light-Weight Vibration Suppression.” 2018. Doctoral Dissertation, University of Michigan. Accessed March 03, 2021. http://hdl.handle.net/2027.42/144044.

MLA Handbook (7^th Edition):

Reichl, Katherine. “Active Metastructures for Light-Weight Vibration Suppression.” 2018. Web. 03 Mar 2021.

Vancouver:

Reichl K. Active Metastructures for Light-Weight Vibration Suppression. [Internet] [Doctoral dissertation]. University of Michigan; 2018. [cited 2021 Mar 03]. Available from: http://hdl.handle.net/2027.42/144044.

Council of Science Editors:

Reichl K. Active Metastructures for Light-Weight Vibration Suppression. [Doctoral Dissertation]. University of Michigan; 2018. Available from: http://hdl.handle.net/2027.42/144044

University of Technology, Sydney

9. Boffa, J. Model reduction of large structural systems for active vibration control.

Degree: 2006, University of Technology, Sydney

URL: http://hdl.handle.net/10453/19983

► This thesis studies the applicability of the Dynamic model reduction method that is used for direct plant order reduction in the active vibration control of… (more)

▼ This thesis studies the applicability of the Dynamic model reduction method that is used for direct plant order reduction in the active vibration control of large and flexible structures. A comparison of the performances between the reduced models produced by the Dynamic model reduction method and those obtained by other common model reduction methods such as the Guyan method, and the Mode-displacement method have been carried out. By using a full analytical model of a twenty storey building as the reference, each three degrees of freedom model was compared by computer simulation. The open-loop frequency response simulation, open-loop earthquake simulation, and the closed-loop earthquake simulation were all used to initially evaluate the reduced models. The accuracy of the frequency responses was assessed with sinusoidal applied forces, and for the closed-loop dynamic analysis, an active mass damper at the top storey and a recorded earthquake excitation was used. When compared with the simulation results of the Guyan method, the Dynamic method has many advantages, especially in terms of its accuracy at the high frequency range. The Mode-displacement method produces reduced models that are good for dynamic analysis of open-loop systems, but it was found to be inconvenient for use in active control. Finally, the Dynamic model reduction method and Guyan method were compared using experimental test results. A 2.5m tall building model with 20 floors was used as the plant, with a linear motor installed at the top storey for the purposes of active-damping. Although the results of simulations would suggest that both models perform sufficiently, experimental testing proved that only the Dynamic model performs adequately for this specific application of active control. The problem associated with most model reduction methods, such as the Guyan, is that they are based on full-order models that were derived from the linear elastic theory. The versatility of the Dynamic model reduction method is such that it provides the option of obtaining system parameters directly from experiment, not just from theory. The experimental procedure ensures that the Dynamic model reduction method forms an accurate description of the real system dynamics. The applicability of this method for obtaining low-order plant models was demonstrated through real-time active control testing of the model structure, while it was subject to a sinusoidal excitation. The tests have shown that the Dynamic model reduction method can be used as an alternative approach for the model reduction of structural systems for the purpose of active vibration control.

Subjects/Keywords: Vibration control.; Buildings vibration.

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APA (6^th Edition):

Boffa, J. (2006). Model reduction of large structural systems for active vibration control. (Thesis). University of Technology, Sydney. Retrieved from http://hdl.handle.net/10453/19983

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Boffa, J. “Model reduction of large structural systems for active vibration control.” 2006. Thesis, University of Technology, Sydney. Accessed March 03, 2021. http://hdl.handle.net/10453/19983.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Boffa, J. “Model reduction of large structural systems for active vibration control.” 2006. Web. 03 Mar 2021.

Vancouver:

Boffa J. Model reduction of large structural systems for active vibration control. [Internet] [Thesis]. University of Technology, Sydney; 2006. [cited 2021 Mar 03]. Available from: http://hdl.handle.net/10453/19983.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Boffa J. Model reduction of large structural systems for active vibration control. [Thesis]. University of Technology, Sydney; 2006. Available from: http://hdl.handle.net/10453/19983

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Michigan State University

10. Wu, Yanzhe. Improvement of vibration test : converting a single-axis vibration table into a two-axis table.

Degree: 2016, Michigan State University

URL: http://etd.lib.msu.edu/islandora/object/etd:4081

►

Thesis M.S. Michigan State University. Packaging 2016

An increasing number of companies find that their products pass standard vibration tests but are damaged during transportation.… (more)

Subjects/Keywords: Packaging – Vibration – Testing; Vibration – Testing; Shipment of goods – Quality control; Packaging

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APA (6^th Edition):

Wu, Y. (2016). Improvement of vibration test : converting a single-axis vibration table into a two-axis table. (Thesis). Michigan State University. Retrieved from http://etd.lib.msu.edu/islandora/object/etd:4081

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Wu, Yanzhe. “Improvement of vibration test : converting a single-axis vibration table into a two-axis table.” 2016. Thesis, Michigan State University. Accessed March 03, 2021. http://etd.lib.msu.edu/islandora/object/etd:4081.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Wu, Yanzhe. “Improvement of vibration test : converting a single-axis vibration table into a two-axis table.” 2016. Web. 03 Mar 2021.

Vancouver:

Wu Y. Improvement of vibration test : converting a single-axis vibration table into a two-axis table. [Internet] [Thesis]. Michigan State University; 2016. [cited 2021 Mar 03]. Available from: http://etd.lib.msu.edu/islandora/object/etd:4081.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Wu Y. Improvement of vibration test : converting a single-axis vibration table into a two-axis table. [Thesis]. Michigan State University; 2016. Available from: http://etd.lib.msu.edu/islandora/object/etd:4081

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Windsor

11. Ahmad, Javaid. In-plane dynamic behaviour of conventional and hybrid cable network systems on cable-stayed bridges.

Degree: PhD, Civil and Environmental Engineering, 2016, University of Windsor

URL: https://scholar.uwindsor.ca/etd/5795

► Stay cables on cable-stayed bridges are vulnerable to dynamic excitations due to their long flexible feature and low intrinsic damping. Connecting a vulnerable cable with… (more)

▼ Stay cables on cable-stayed bridges are vulnerable to dynamic excitations due to their long flexible feature and low intrinsic damping. Connecting a vulnerable cable with the neighbouring ones through cross-ties to form a cable network is one of the commonly used field solutions. The current dissertation is dedicated to explore the in-plane dynamic behaviour of the conventional (cross-tie only) and hybrid (combined use of cross-ties and external dampers) cable networks used for controlling undesirable bridge stay cable vibrations. Their performances are evaluated based on the system in-plane stiffness, damping and the severity of local mode formation. A number of analytical models have been developed to analyze the in-plane modal response of conventional cable networks by gradually extending the model of a basic undamped two-cable network with a rigid cross-tie to include the cross-tie stiffness, the damping property of main cables and cross-tie, and more number of main cables and cross-tie lines into the formulation. A damping transfer phenomenon between cable network elements having different damping properties was observed. Two criteria, the degree of mode localization (DML) coefficient and the local mode cluster (LMC), were proposed to quantify the severity of local mode formation. Based on the proposed analytical models, key system parameters which dictate the dynamic behaviour of conventional cable networks were identified. A parametric study was conducted to explore their respective role in influencing the in-plane stiffness, the damping ratio and the local mode formation of cable networks. Analytical models of two-cable hybrid networks with different configurations have been developed to assess the system in-plane modal behaviour. A concept of “isoquant curve” was proposed to optimize the performance of a selected hybrid system mode. A state-of-the-art generalized approach was developed to derive analytical models of a more complex conventional or hybrid cable network from a relatively simple parent system. Results indicated that the existing universal damping estimation curve for a single isolated damped cable was no longer applicable once the cable became part of a hybrid system. Thus, approximate relation equations were developed to predict the optimum damper size and the maximum attainable fundamental modal damping ratio of a basic two-cable hybrid system. All the proposed analytical models were validated through independent numerical simulations using the commercial finite element software Abaqus 6.10. Besides, an experimental study was conducted for two-cable conventional and hybrid networks to not only verify the validity of the corresponding analytical and numerical models, but also evaluate the impact of different assumptions made in the formulation of these models on the system modal response. The outcomes yielded from this study are expected to add valuable knowledge to comprehend the current understanding of the mechanics associated with the conventional and hybrid cable networks. The developed… Advisors/Committee Members: Cheng, Shaohong, Ghrib, Faouzi.

Subjects/Keywords: cable-stayed bridge; cable vibration; cross-tie; damper; damping; vibration control

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APA (6^th Edition):

Ahmad, J. (2016). In-plane dynamic behaviour of conventional and hybrid cable network systems on cable-stayed bridges. (Doctoral Dissertation). University of Windsor. Retrieved from https://scholar.uwindsor.ca/etd/5795

Chicago Manual of Style (16^th Edition):

Ahmad, Javaid. “In-plane dynamic behaviour of conventional and hybrid cable network systems on cable-stayed bridges.” 2016. Doctoral Dissertation, University of Windsor. Accessed March 03, 2021. https://scholar.uwindsor.ca/etd/5795.

MLA Handbook (7^th Edition):

Ahmad, Javaid. “In-plane dynamic behaviour of conventional and hybrid cable network systems on cable-stayed bridges.” 2016. Web. 03 Mar 2021.

Vancouver:

Ahmad J. In-plane dynamic behaviour of conventional and hybrid cable network systems on cable-stayed bridges. [Internet] [Doctoral dissertation]. University of Windsor; 2016. [cited 2021 Mar 03]. Available from: https://scholar.uwindsor.ca/etd/5795.

Council of Science Editors:

Ahmad J. In-plane dynamic behaviour of conventional and hybrid cable network systems on cable-stayed bridges. [Doctoral Dissertation]. University of Windsor; 2016. Available from: https://scholar.uwindsor.ca/etd/5795

University of Bath

12. Gan, Zengkang. Adaptive control of an active seat for occupant vibration reduction.

Degree: PhD, 2015, University of Bath

URL: https://researchportal.bath.ac.uk/en/studentthesis/adaptive-control-of-an-active-seat-for-occupant-vibration-reduction(b88fa32c-2e76-464b-9ab0-4f3e305bb1a8).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.665426

► Vehicle occupants are typically exposed to unpleasant whole-body vibration (WBV) for extended period of time. It is well known that the transmission of unwanted vibration… (more)

▼ Vehicle occupants are typically exposed to unpleasant whole-body vibration (WBV) for extended period of time. It is well known that the transmission of unwanted vibration to the human body can lead to fatigue and discomfort. Moreover, the unwanted vibration normally distributed in the low-frequency range has been found as the main risk factor for lower back pain and lumbago, which seriously affect the health and working performance of occupants. Thus vibration cancellation on seats has attracted considerable interest in recent years. So far, for most vehicle seats, vibration isolation is achieved passively by using seat cushions and conventional energy absorbers, which have very limited performance in the low-frequency range. The work presented in this thesis forms a successful development and experimental study of an active seat and control algorithm for occupants’ WBV reduction under low frequency excitations. Firstly, a modelling study of the seat human subjects (SHS) and an extensive experimental measurement of the vibration transmissibility of a test dummy and vehicle seat are carried out. The biodynamic responses of SHS exposed to uncoupled vertical and fore-and-aft WBV is modelled. A comparison with the existing models is made and the results show that an improved fit with the aggregated experimental data is achieved. Secondly, an active seat is developed based upon the observations and understanding of the SHS and seat system. The characteristics of the active seat dynamics are identified through experimental tests found suitable for the development of an active seat to attenuate the vibration experienced by vehicle occupants. The vibration cancellation performance of the active seat is initially examined by feedforward plus proportional-integral (PI) control tests. Through these tests, the effectiveness of the actuators control authority is verified, but the limitations are also revealed. Because the active seat system is subject to non-linear and time-varying behaviour, a self-tuning fully adaptive algorithm is a prime requirement. The Filtered-x Least-Mean-Square (FXLMS) algorithm with the Fast-block LMS (FBLMS) system identification technique is found suitable for this application and is investigated through experimental tests. Substantial vibration reductions are achieved for a variety of input vibration profiles. An excellent capability of the active seat and control system for efficiently reducing the vibration level of seated occupants under low-frequency WBV is demonstrated.

Subjects/Keywords: 620.3; vibration isolation; Adaptive control; Biodynamics; Whole-body vibration

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APA (6^th Edition):

Gan, Z. (2015). Adaptive control of an active seat for occupant vibration reduction. (Doctoral Dissertation). University of Bath. Retrieved from https://researchportal.bath.ac.uk/en/studentthesis/adaptive-control-of-an-active-seat-for-occupant-vibration-reduction(b88fa32c-2e76-464b-9ab0-4f3e305bb1a8).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.665426

Chicago Manual of Style (16^th Edition):

Gan, Zengkang. “Adaptive control of an active seat for occupant vibration reduction.” 2015. Doctoral Dissertation, University of Bath. Accessed March 03, 2021. https://researchportal.bath.ac.uk/en/studentthesis/adaptive-control-of-an-active-seat-for-occupant-vibration-reduction(b88fa32c-2e76-464b-9ab0-4f3e305bb1a8).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.665426.

MLA Handbook (7^th Edition):

Gan, Zengkang. “Adaptive control of an active seat for occupant vibration reduction.” 2015. Web. 03 Mar 2021.

Vancouver:

Gan Z. Adaptive control of an active seat for occupant vibration reduction. [Internet] [Doctoral dissertation]. University of Bath; 2015. [cited 2021 Mar 03]. Available from: https://researchportal.bath.ac.uk/en/studentthesis/adaptive-control-of-an-active-seat-for-occupant-vibration-reduction(b88fa32c-2e76-464b-9ab0-4f3e305bb1a8).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.665426.

Council of Science Editors:

Gan Z. Adaptive control of an active seat for occupant vibration reduction. [Doctoral Dissertation]. University of Bath; 2015. Available from: https://researchportal.bath.ac.uk/en/studentthesis/adaptive-control-of-an-active-seat-for-occupant-vibration-reduction(b88fa32c-2e76-464b-9ab0-4f3e305bb1a8).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.665426

Universidade Estadual de Campinas

13. Melo, Fábio Menegatti de, 1988-. On the use of particle impact dampers to control vertical impact-induced vibration : an experimental investigation = Uso de absorvedores por efeito de impacto multi-particulados no controle de vibrações verticais impacto-induzidas: estudo experimental: Uso de absorvedores por efeito de impacto multi-particulados no controle de vibrações verticais impacto-induzidas : estudo experimental.

Degree: 2018, Universidade Estadual de Campinas

URL: http://repositorio.unicamp.br/jspui/handle/REPOSIP/332023

► Abstract: Particle impact dampers (\emph{PIDs}) are devices that have been explored as an alternative to the conventional methods employed in the passive control of noise… (more)

Subjects/Keywords: Vibração; Controle de ruído; Vibration; Noise control

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APA (6^th Edition):

Melo, Fábio Menegatti de, 1. (2018). On the use of particle impact dampers to control vertical impact-induced vibration : an experimental investigation = Uso de absorvedores por efeito de impacto multi-particulados no controle de vibrações verticais impacto-induzidas: estudo experimental: Uso de absorvedores por efeito de impacto multi-particulados no controle de vibrações verticais impacto-induzidas : estudo experimental. (Thesis). Universidade Estadual de Campinas. Retrieved from http://repositorio.unicamp.br/jspui/handle/REPOSIP/332023

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Melo, Fábio Menegatti de, 1988-. “On the use of particle impact dampers to control vertical impact-induced vibration : an experimental investigation = Uso de absorvedores por efeito de impacto multi-particulados no controle de vibrações verticais impacto-induzidas: estudo experimental: Uso de absorvedores por efeito de impacto multi-particulados no controle de vibrações verticais impacto-induzidas : estudo experimental.” 2018. Thesis, Universidade Estadual de Campinas. Accessed March 03, 2021. http://repositorio.unicamp.br/jspui/handle/REPOSIP/332023.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Melo, Fábio Menegatti de, 1988-. “On the use of particle impact dampers to control vertical impact-induced vibration : an experimental investigation = Uso de absorvedores por efeito de impacto multi-particulados no controle de vibrações verticais impacto-induzidas: estudo experimental: Uso de absorvedores por efeito de impacto multi-particulados no controle de vibrações verticais impacto-induzidas : estudo experimental.” 2018. Web. 03 Mar 2021.

Vancouver:

Melo, Fábio Menegatti de 1. On the use of particle impact dampers to control vertical impact-induced vibration : an experimental investigation = Uso de absorvedores por efeito de impacto multi-particulados no controle de vibrações verticais impacto-induzidas: estudo experimental: Uso de absorvedores por efeito de impacto multi-particulados no controle de vibrações verticais impacto-induzidas : estudo experimental. [Internet] [Thesis]. Universidade Estadual de Campinas; 2018. [cited 2021 Mar 03]. Available from: http://repositorio.unicamp.br/jspui/handle/REPOSIP/332023.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Melo, Fábio Menegatti de 1. On the use of particle impact dampers to control vertical impact-induced vibration : an experimental investigation = Uso de absorvedores por efeito de impacto multi-particulados no controle de vibrações verticais impacto-induzidas: estudo experimental: Uso de absorvedores por efeito de impacto multi-particulados no controle de vibrações verticais impacto-induzidas : estudo experimental. [Thesis]. Universidade Estadual de Campinas; 2018. Available from: http://repositorio.unicamp.br/jspui/handle/REPOSIP/332023

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

14. Waghulde, Kishor Bhaskar. Vibration analysis and control of piezoelectric smart structures by finite element method; -.

Degree: Chemical Technology, 2013, North Maharashtra University

URL: http://shodhganga.inflibnet.ac.in/handle/10603/36152

Abstract avalible

Reference p.166 - 179 and Appendix given

Advisors/Committee Members: Kumar, Bimlesh.

Subjects/Keywords: control; piezoelectric; Vibration

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APA (6^th Edition):

Waghulde, K. B. (2013). Vibration analysis and control of piezoelectric smart structures by finite element method; -. (Thesis). North Maharashtra University. Retrieved from http://shodhganga.inflibnet.ac.in/handle/10603/36152

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Waghulde, Kishor Bhaskar. “Vibration analysis and control of piezoelectric smart structures by finite element method; -.” 2013. Thesis, North Maharashtra University. Accessed March 03, 2021. http://shodhganga.inflibnet.ac.in/handle/10603/36152.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Waghulde, Kishor Bhaskar. “Vibration analysis and control of piezoelectric smart structures by finite element method; -.” 2013. Web. 03 Mar 2021.

Vancouver:

Waghulde KB. Vibration analysis and control of piezoelectric smart structures by finite element method; -. [Internet] [Thesis]. North Maharashtra University; 2013. [cited 2021 Mar 03]. Available from: http://shodhganga.inflibnet.ac.in/handle/10603/36152.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Waghulde KB. Vibration analysis and control of piezoelectric smart structures by finite element method; -. [Thesis]. North Maharashtra University; 2013. Available from: http://shodhganga.inflibnet.ac.in/handle/10603/36152

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Anna University

15. Yuvaraja M. Investigations on vibration control Of structures using smart materials;.

Degree: Investigations on vibration control Of structures using smart materials, 2015, Anna University

URL: http://shodhganga.inflibnet.ac.in/handle/10603/39429

►

Design in the fields of aeronautical, mechanical and civil requires Lighter stronger and more flexible structures However light weight structures newlinecan be more easily influenced… (more)

Subjects/Keywords: Active vibration control; Lighter stronger; piezoelectricshape

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APA (6^th Edition):

M, Y. (2015). Investigations on vibration control Of structures using smart materials;. (Thesis). Anna University. Retrieved from http://shodhganga.inflibnet.ac.in/handle/10603/39429

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

M, Yuvaraja. “Investigations on vibration control Of structures using smart materials;.” 2015. Thesis, Anna University. Accessed March 03, 2021. http://shodhganga.inflibnet.ac.in/handle/10603/39429.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

M, Yuvaraja. “Investigations on vibration control Of structures using smart materials;.” 2015. Web. 03 Mar 2021.

Vancouver:

M Y. Investigations on vibration control Of structures using smart materials;. [Internet] [Thesis]. Anna University; 2015. [cited 2021 Mar 03]. Available from: http://shodhganga.inflibnet.ac.in/handle/10603/39429.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

M Y. Investigations on vibration control Of structures using smart materials;. [Thesis]. Anna University; 2015. Available from: http://shodhganga.inflibnet.ac.in/handle/10603/39429

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

University of Saskatchewan

16. Sharbati, Ehsan. Mechanics and FEM simulation of active vibration control in structural systems by using internal mass reconfiguration.

Degree: 2011, University of Saskatchewan

URL: http://hdl.handle.net/10388/ETD-2011-09-68

► Relative motion of different parts of a structure can affect its vibrations that may be amplified or attenuated. If such a motion is properly devised,… (more)

▼ Relative motion of different parts of a structure can affect its vibrations that may be amplified or attenuated. If such a motion is properly devised, it can lead to continuous attenuation of vibration and thus be used for eliminating vibration of the structure, as has been shown in previous works on an oscillating physical pendulum. In this thesis, the moving mass/structure interaction is investigated in order to devise a numerical tool for modeling such problems for arbitrary structures. The mass (or masses) motion patterns are synchronized such that a continuous attenuation of vibration is achieved. This is a novel technique for active vibration control especially for structures where the conventional stationary actuators are not practical. To analyze the dynamic response of such moving mass-structure systems, a ‘composite’ beam element is introduced that permits extending the conventional finite element formulation (and software) and explicitly identifying the Coriolis and centripetal inertia effects of the moving mass. A numerical procedure is then proposed in which these inertia effects are included in the finite element model as fictitious transversal and axial forces applied to the beam element currently being traversed by the moving mass. The proposed approach is verified by comparing the results with those available in the literature as well as exact solutions possible for the pendulum. Numerical simulations show that the periodic relative motion of the mass with a constant frequency normally tends to amplify vibration. In order to obtain a continuous attenuation, a proper synchronization method is required. It is demonstrated that such synchronization can be determined to be effective for vibration control of different structures. In particular, for structures which can be treated as uni-modal, like the pendulum, the method is quite effective with a relatively high vibration attenuation rate. For multi-modal structures, represented by beams and frames in this thesis, the vibration attenuation is less smooth and more complicated mass motion patterns and synchronization methods are needed. It is concluded that the effectiveness of such active vibration control depends on how distinct the vibration modes to be attenuated are in the frequency spectrum. Advisors/Committee Members: Szyszkowski, Walerian, Burton, Richard, Sparling, Bruce, Fotouhi, Reza.

Subjects/Keywords: moving mass; vibration control; finite element method

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APA (6^th Edition):

Sharbati, E. (2011). Mechanics and FEM simulation of active vibration control in structural systems by using internal mass reconfiguration. (Thesis). University of Saskatchewan. Retrieved from http://hdl.handle.net/10388/ETD-2011-09-68

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Sharbati, Ehsan. “Mechanics and FEM simulation of active vibration control in structural systems by using internal mass reconfiguration.” 2011. Thesis, University of Saskatchewan. Accessed March 03, 2021. http://hdl.handle.net/10388/ETD-2011-09-68.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Sharbati, Ehsan. “Mechanics and FEM simulation of active vibration control in structural systems by using internal mass reconfiguration.” 2011. Web. 03 Mar 2021.

Vancouver:

Sharbati E. Mechanics and FEM simulation of active vibration control in structural systems by using internal mass reconfiguration. [Internet] [Thesis]. University of Saskatchewan; 2011. [cited 2021 Mar 03]. Available from: http://hdl.handle.net/10388/ETD-2011-09-68.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Sharbati E. Mechanics and FEM simulation of active vibration control in structural systems by using internal mass reconfiguration. [Thesis]. University of Saskatchewan; 2011. Available from: http://hdl.handle.net/10388/ETD-2011-09-68

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Texas A&M University

17. Wright, Evan Dalton. Feasibility of Using Nonlinear Time-Frequency Control for Magnetorheological Dampers in Vehicle Suspension.

Degree: MS, Mechanical Engineering, 2017, Texas A&M University

URL: http://hdl.handle.net/1969.1/174890

► Semi-active vehicle suspensions that use magnetorheological (MR) dampers are able to better dissipate vibrations compared to conventional dampers because of their controllable damping characteristics. The… (more)

▼ Semi-active vehicle suspensions that use magnetorheological (MR) dampers are able to better dissipate vibrations compared to conventional dampers because of their controllable damping characteristics. The performance of current MR damper control methods is often hindered by incorrect assumptions and linearized models. Therefore, a need exists to design an adaptive controller with improved accuracy and reliability. The objective of this research is to design an improved controller for MR dampers in vehicle suspension using the nonlinear time-frequency control approach and evaluate its feasibility by numerically employing MATLAB Simulink. Simulations in this research are performed using a simplified quarter car suspension model and modified Bouc-Wen damper model. The proposed control method is evaluated based on its ability to reduce the amplitude of vibrations and minimize acceleration of the car body for various test cases. Simulations are also performed using the skyhook controller and passive suspension to assess the performance of the proposed controller. The results of the simulations show that the proposed nonlinear time-frequency controller can successfully be applied to an MR damper suspensions system for vibration control. The proposed controller outperforms the skyhook controller in terms of reducing acceleration of the car body in each of the tested scenarios. The proposed controller also shows the ability to more efficiently manage the current input to the system. In general, the skyhook controller gives more improved vibration amplitude responses but is prone to generate large spikes in car body acceleration at higher frequency road profile inputs. Simulations performed with the passive system show large displacement amplitudes and inability to prevent oscillation. The feed-forward aspect and adaptive nature of the proposed controller gives it the ability to better compensate for the time-delay in the operation of the MR damper. The proposed controller shows sensitivity to controller parameters when pursuing the best response for different road profile input cases. Advisors/Committee Members: Suh, Chii-Der (advisor), Lau, Sai (committee member), Hurlebaus, Stefan (committee member).

Subjects/Keywords: magnetorheological damper; semi-active vibration control

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APA (6^th Edition):

Wright, E. D. (2017). Feasibility of Using Nonlinear Time-Frequency Control for Magnetorheological Dampers in Vehicle Suspension. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/174890

Chicago Manual of Style (16^th Edition):

Wright, Evan Dalton. “Feasibility of Using Nonlinear Time-Frequency Control for Magnetorheological Dampers in Vehicle Suspension.” 2017. Masters Thesis, Texas A&M University. Accessed March 03, 2021. http://hdl.handle.net/1969.1/174890.

MLA Handbook (7^th Edition):

Wright, Evan Dalton. “Feasibility of Using Nonlinear Time-Frequency Control for Magnetorheological Dampers in Vehicle Suspension.” 2017. Web. 03 Mar 2021.

Vancouver:

Wright ED. Feasibility of Using Nonlinear Time-Frequency Control for Magnetorheological Dampers in Vehicle Suspension. [Internet] [Masters thesis]. Texas A&M University; 2017. [cited 2021 Mar 03]. Available from: http://hdl.handle.net/1969.1/174890.

Council of Science Editors:

Wright ED. Feasibility of Using Nonlinear Time-Frequency Control for Magnetorheological Dampers in Vehicle Suspension. [Masters Thesis]. Texas A&M University; 2017. Available from: http://hdl.handle.net/1969.1/174890

University of Adelaide

18. Blunt, David Mark. Optimisation and adaptive control of aircraft propeller synchrophase angles.

Degree: 2012, University of Adelaide

URL: http://hdl.handle.net/2440/75757

► This thesis provides a new and detailed examination of how the optimum propeller synchrophase angles for minimum cabin noise and vibration vary with different flight… (more)

▼ This thesis provides a new and detailed examination of how the optimum propeller synchrophase angles for minimum cabin noise and vibration vary with different flight conditions, particularly altitude and airspeed, and how, based on these observations, adaptive control techniques could best be employed to further improve the noise-reducing potential of synchrophasing. This has been done through experimental investigations in one AP-3C Orion and two C-130J-30 Super Hercules aircraft. It is shown, using propeller signature theory, that synchrophasing has significant effects on the average cabin floor vibration and the average cabin sound pressure levels. In the trial aircraft, these effects range between 4 dB and 12 dB at the blade-pass frequency, depending on the flight condition and the aircraft. The effects at individual sensors locations can, however, sometimes exceed 20 dB. It is also shown that the effects of altitude and airspeed on the optimum synchrophase angles are significant, and that a fixed set of synchrophase angles cannot be optimal for more than a limited range of flight conditions. For example, over the range of altitudes and airspeeds considered in this investigation, a fixed set of angles is shown to produce results that can vary by more than half of the range from the lowest to the highest predicted average sound pressure level at the blade-pass frequency. Adaptive control of the synchrophase angles using pre-defined look-up tables or active control algorithms are considered, and the latter recommended for their ability to compensate for unknown and variable influencing factors. Two ranking strategies are developed and employed to identify the number and placement of error sensors for an active control system. Significantly, both strategies identify that the predicted average sound pressure levels at the blade-pass frequency in the trial aircraft could be maintained within 2 dB of the optimum across all considered flight conditions using as few as 3 to 6 well-placed microphones. A single-input (master propeller tachometer) multi-output (slave propeller synchrophase angles) feed-forward active control system with multiple error sensors (microphones or accelerometers) is developed using propeller signature theory and the Filtered-x LMS algorithm. Recommendations for further work are also made. Advisors/Committee Members: Hansen, Colin Henry (advisor), Zander, Anthony Charles (advisor), School of Mechanical Engineering (school).

Subjects/Keywords: aircraft; propeller; noise; vibration; active control; synchrophasing

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APA (6^th Edition):

Blunt, D. M. (2012). Optimisation and adaptive control of aircraft propeller synchrophase angles. (Thesis). University of Adelaide. Retrieved from http://hdl.handle.net/2440/75757

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Blunt, David Mark. “Optimisation and adaptive control of aircraft propeller synchrophase angles.” 2012. Thesis, University of Adelaide. Accessed March 03, 2021. http://hdl.handle.net/2440/75757.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Blunt, David Mark. “Optimisation and adaptive control of aircraft propeller synchrophase angles.” 2012. Web. 03 Mar 2021.

Vancouver:

Blunt DM. Optimisation and adaptive control of aircraft propeller synchrophase angles. [Internet] [Thesis]. University of Adelaide; 2012. [cited 2021 Mar 03]. Available from: http://hdl.handle.net/2440/75757.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Blunt DM. Optimisation and adaptive control of aircraft propeller synchrophase angles. [Thesis]. University of Adelaide; 2012. Available from: http://hdl.handle.net/2440/75757

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

New Jersey Institute of Technology

19. Feizi, Bakhtiar. Application of mass/stiffness eccentricity to control response of structures subjected to earthquake ground motion.

Degree: PhD, Civil and Environmental Engineering, 2011, New Jersey Institute of Technology

URL: https://digitalcommons.njit.edu/dissertations/236

► This dissertation is driven by the concept that engaging more modes in the response of structures can be used to mitigate its translational dynamic… (more)

▼ This dissertation is driven by the concept that engaging more modes in the response of structures can be used to mitigate its translational dynamic response. One such an approach is to engage torsional modes through engineered eccentricity (mass/stiffness eccentricity), thus, introducing coupled translation-rotation response. This idea was first introduced in a paper published by MacBain and Spillers in 2004. As a follow up to the same idea this dissertation was an attempt to investigate and develop the theory concerning the application of mass/stiffness eccentricity to control the translational motion of structures subjected to earthquake ground motion. Different discrete and continuous mathematical models of structures were used for this study. Discrete models are single story building and multi story building, and continuous models are shear beam and flexural beam. Initially, the steady state behavior of eccentric structures was analyzed. This type of analysis proved to be revealing in terms of parameters that impact the response mitigation. A sufficient and necessary condition under which increasing eccentricity in a single story building always leads to mitigation of translational displacement was deducted. Moreover it was observed that in addition to the eccentricity the relationship between dominant translational frequency to dominant rotational frequency plays a significant role in the magnitude of reductions. Furthermore through conducting a statistical analysis the seismic effectiveness of the proposed method was investigated. For this purpose the structural models were exposed to 16 real earthquake records. The records were selected in a way that a broad range of frequency content were covered. The records are applied to structures with different eccentricities and frequency ratios. Altogether 5632 analyses were performed. The results showed that eccentricity was indeed effective in reducing the average translational displacements up to 30%. Moreover, using the data obtained from time history analyses the variation of reductions with eccentricity and frequency ratio was studied. The dissertation continued with proposing a systematic approach for finding the eccentricities and frequency ratio that lead to the maximum reduction in displacements. To address this issue an optimization problem in frequency domain was formulated. The mean square value of response was selected as the performance function. Two types of constraints including limitations on rotations and eccentricity were imposed. Kanai- Tajimi power spectral density function was used to model the ground motion. It was observed that this approach could be used to decrease the performance function up to 50%. Finally through a case study the performance of the proposed approach was compared with tuned mass dampers (TMD). The results showed that the proposed method could be as effective as TMDs. Even in some cases more reductions in displacements could be achieved. Advisors/Committee Members: M. Ala Saadeghvaziri, C.T. Thomas Hsu, Taha F. Marhaba.

Subjects/Keywords: Vibration control; Eccentricity; Earthquake engineering; Civil Engineering

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APA (6^th Edition):

Feizi, B. (2011). Application of mass/stiffness eccentricity to control response of structures subjected to earthquake ground motion. (Doctoral Dissertation). New Jersey Institute of Technology. Retrieved from https://digitalcommons.njit.edu/dissertations/236

Chicago Manual of Style (16^th Edition):

Feizi, Bakhtiar. “Application of mass/stiffness eccentricity to control response of structures subjected to earthquake ground motion.” 2011. Doctoral Dissertation, New Jersey Institute of Technology. Accessed March 03, 2021. https://digitalcommons.njit.edu/dissertations/236.

MLA Handbook (7^th Edition):

Feizi, Bakhtiar. “Application of mass/stiffness eccentricity to control response of structures subjected to earthquake ground motion.” 2011. Web. 03 Mar 2021.

Vancouver:

Feizi B. Application of mass/stiffness eccentricity to control response of structures subjected to earthquake ground motion. [Internet] [Doctoral dissertation]. New Jersey Institute of Technology; 2011. [cited 2021 Mar 03]. Available from: https://digitalcommons.njit.edu/dissertations/236.

Council of Science Editors:

Feizi B. Application of mass/stiffness eccentricity to control response of structures subjected to earthquake ground motion. [Doctoral Dissertation]. New Jersey Institute of Technology; 2011. Available from: https://digitalcommons.njit.edu/dissertations/236

Louisiana State University

20. Guerra, Jorge Antonio. Closed form solutions to the optimality equation of minimal norm actuation.

Degree: MSME, Mechanical Engineering, 2013, Louisiana State University

URL: etd-11072013-150451 ; https://digitalcommons.lsu.edu/gradschool_theses/3664

► This research focused on the problem of minimal norm actuation in the context of partial natural frequency or pole assignment applied to undamped vibrating systems… (more)

▼ This research focused on the problem of minimal norm actuation in the context of partial natural frequency or pole assignment applied to undamped vibrating systems by state feedback control. The result of the research was the closed form solutions for the minimal norm control input and gain vectors. These closed form solutions should took open loop eigenpairs and the desired frequencies of the controlled system and outputted the optimal controller parameters. This optimization technique ensures that the system’s dynamics will be effectively controlled while keeping the controller effort minimal. The controller must then be able to shift only the desired the system poles anywhere in the complex s-plane in order to give the system certain desired characteristics with no spillover. The open loop system dynamics were found by applying a discrete model of the studied vibrating system and then finding the eigenvalue problem associated with the second-order open loop system equations. A first order realization was then performed on the system in order to know its response to certain initial conditions. The system’s dynamics where to be modified via closed loop control. Partial natural frequency assignment was chosen as the control technique so that certain system frequencies could be left untouched to ensure that the system will not respond in an unexpected manner. The control was to be optimized by minimizing the norm of the control input and gain vectors. A closed form solution for these vectors was found in so that these vectors could be simply calculated using an algorithm that takes the open loop eigenpairs and the desired eigenvalues of the system and outputs the two vectors. This closed form solution was successful implemented and the controller parameters found were applied to a vibrational system. A simulation for the un-optimized and optimized cases was performed applying both controllers to the same system. The response and controller forces for both cases were plotted in MATLAB and compared. Both systems showed the desired system response meaning that they both had the same effect on the system. Inspecting both controller efforts showed that the optimal control case simulation showed less controller effort than the arbitrary case thus showing successful implementation of minimal norm actuation.

Subjects/Keywords: Optimality; Actuation; Vibration Control; Minimal Norm Actuation

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APA (6^th Edition):

Guerra, J. A. (2013). Closed form solutions to the optimality equation of minimal norm actuation. (Masters Thesis). Louisiana State University. Retrieved from etd-11072013-150451 ; https://digitalcommons.lsu.edu/gradschool_theses/3664

Chicago Manual of Style (16^th Edition):

Guerra, Jorge Antonio. “Closed form solutions to the optimality equation of minimal norm actuation.” 2013. Masters Thesis, Louisiana State University. Accessed March 03, 2021. etd-11072013-150451 ; https://digitalcommons.lsu.edu/gradschool_theses/3664.

MLA Handbook (7^th Edition):

Guerra, Jorge Antonio. “Closed form solutions to the optimality equation of minimal norm actuation.” 2013. Web. 03 Mar 2021.

Vancouver:

Guerra JA. Closed form solutions to the optimality equation of minimal norm actuation. [Internet] [Masters thesis]. Louisiana State University; 2013. [cited 2021 Mar 03]. Available from: etd-11072013-150451 ; https://digitalcommons.lsu.edu/gradschool_theses/3664.

Council of Science Editors:

Guerra JA. Closed form solutions to the optimality equation of minimal norm actuation. [Masters Thesis]. Louisiana State University; 2013. Available from: etd-11072013-150451 ; https://digitalcommons.lsu.edu/gradschool_theses/3664

University of New South Wales

21. Gangemi, Peter. Attenuation of the structural and acoustic responses of a submerged hull.

Degree: Mechanical & Manufacturing Engineering, 2015, University of New South Wales

URL: http://handle.unsw.edu.au/1959.4/54628 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:35415/SOURCE02?view=true

► As the only true covert naval option, Submarines are in constant demand around the world. Reducing the structure borne noise from the hull is one… (more)

▼ As the only true covert naval option, Submarines are in constant demand around the world. Reducing the structure borne noise from the hull is one of the highest priorities associated with Submarine design. The major sources of underwater noise from maritime vessels include onboard machinery, wake from the propeller, flow of fluid over the hull and excitation of the global hull resonances. At low frequencies, rotation of the propeller results in discrete tones at the blade passing frequency and its harmonics. The fluctuating forces at the propeller are transmitted through the propulsion system, resulting in excitation of the low frequency hull vibrational modes, which in turn results in a high level of structure-borne radiated noise. In this thesis, the low frequency vibro-acoustic responses from a submerged hull are determined and then attenuated using control strategies. Analytical and computational models of the submarine are created, allowing the structural responses of the hull and the far field acoustic responses to be obtained. The submarine hull is represented by a thin walled cylindrical shell, with additional complicating effects including ring-stiffeners, bulkheads, external fluid loading and ballast tanks. Novel control methods are utilised to attenuate the structural response of the submerged hull. Passive tuned vibration absorbers, active vibration control, hybrid vibration absorbers and compliant coatings are used to attenuate the breathing and higher order modes of the submerged hull. Attenuation of the higher order hull modes by active and hybrid means has rarely been examined. To the best of the author’s knowledge, the use of compliant coatings in conjunction with active or hybrid technologies has never been investigated. This thesis fills these gaps in the research. The highest level of attenuation is achieved from the use of the hybrid and coating technologies. The hybrid vibration absorbers provide greater attenuation than the passive control with a lower control force requirement than the active treatment. The acoustic coatings provide significant attenuation at the anti resonances. This thesis shows that passive, active, hybrid and coating treatments reduce the structural and acoustic responses of the submerged hull. Advisors/Committee Members: Kanapathipillai‎, Kana, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW.

Subjects/Keywords: Hull; Submarine; Submerged; Control; Vibration; Acoustics

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APA (6^th Edition):

Gangemi, P. (2015). Attenuation of the structural and acoustic responses of a submerged hull. (Doctoral Dissertation). University of New South Wales. Retrieved from http://handle.unsw.edu.au/1959.4/54628 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:35415/SOURCE02?view=true

Chicago Manual of Style (16^th Edition):

Gangemi, Peter. “Attenuation of the structural and acoustic responses of a submerged hull.” 2015. Doctoral Dissertation, University of New South Wales. Accessed March 03, 2021. http://handle.unsw.edu.au/1959.4/54628 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:35415/SOURCE02?view=true.

MLA Handbook (7^th Edition):

Gangemi, Peter. “Attenuation of the structural and acoustic responses of a submerged hull.” 2015. Web. 03 Mar 2021.

Vancouver:

Gangemi P. Attenuation of the structural and acoustic responses of a submerged hull. [Internet] [Doctoral dissertation]. University of New South Wales; 2015. [cited 2021 Mar 03]. Available from: http://handle.unsw.edu.au/1959.4/54628 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:35415/SOURCE02?view=true.

Council of Science Editors:

Gangemi P. Attenuation of the structural and acoustic responses of a submerged hull. [Doctoral Dissertation]. University of New South Wales; 2015. Available from: http://handle.unsw.edu.au/1959.4/54628 ; https://unsworks.unsw.edu.au/fapi/datastream/unsworks:35415/SOURCE02?view=true

University of Adelaide

22. Tang, Difan. Active Suppression ofAerofoil Flutter via Neural-Network-Based Adaptive Nonlinear Optimal Control.

Degree: 2019, University of Adelaide

URL: http://hdl.handle.net/2440/123093

► This thesis deals with active flutter suppression (AFS) on aerofoils via adaptive nonlinear optimal control using neural networks (NNs). Aeroelastic flutter can damage aerofoils if… (more)

▼ This thesis deals with active flutter suppression (AFS) on aerofoils via adaptive nonlinear optimal control using neural networks (NNs). Aeroelastic flutter can damage aerofoils if not properly controlled. AFS not only ensures flutter-free flight but also enables the use of aerodynamically more efficient lightweight aerofoils. However, existing optimal controllers for AFS are generally susceptible to modelling errors while other controllers less prone to uncertainties do not provide optimal control. This thesis, thus, aims to reduce the impact of the dilemma by proposing new solutions based on nonlinear optimal control online synthesis (NOCOS) according to online updated dynamics. Existing NOCOS methods, with NNs as essential elements, require a separate initial stabilising control law for the overall system, an additional stabilising tuning loop for the actor NN, or an additional stabilising term in the critic NN tuning law, to guarantee the closed-loop stability for unstable and marginally stable systems. The resulting complexity is undesired in AFS applications due to computational concerns in real-time implementation. Moreover, the existing NOCOS methods are confined to locally nonlinear systems, while aeroelastic systems under consideration are globally nonlinear. These make all the existing NOCOS algorithms inapplicable to AFS without modification and improvement. Therefore, this thesis solves the aforementioned problems through the following step-by-step approaches. Firstly, a four degrees-of-freedom (4-DOF) aeroelastic model is considered, where leading- and trailing-edge control surfaces of the aerofoil are used to actively suppress flutter. Accordingly, a virtual stiffness-damping system (VSDS) is developed to simulate physical stiffness in the aeroelastic system. The VSDS, together with a scaled-down typical aerofoil section placed in a wind tunnel, serve as an experimental 4-DOF aeroelastic test-bed for synthesis and validation of proposed AFS controllers that follow. Secondly, a Modified form of NN-based Value Function Approximation (MVFA), tuned by gradient-descent learning, is proposed for NOCOS to address the closedloop stability in a compact controller configuration suitable for real-time implementation. Its validity and efficacy are examined by the Lyapunov stability analysis and numerical studies. Thirdly, a systematic procedure based on linear matrix inequalities is further proposed for synthesising a scheduled parameter matrix to generalise the MVFA to to globally nonlinear cases, so that the new NN controller suits AFS applications. In addition, the extended Kalman filter (EKF) is proposed for the new NN controller for fast parameter convergence. An identifier NN is also derived to capture and update aeroelastic dynamics in real time to mitigate the impact of modelling errors. Wind-tunnel experiments were conducted for validation. Finally, a non-quadratic functional is introduced to generalise the performance index to tackle the problem where control inputs are constrained. The feasibility of… Advisors/Committee Members: Chen, Lei (advisor), Tian, Zhao Feng (advisor), Hu, Eric (advisor), School of Chemical Engineering (school).

Subjects/Keywords: adaptive control; aeroelasticity; flutter; neural network; nonlinear control; optimal control; vibration

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APA (6^th Edition):

Tang, D. (2019). Active Suppression ofAerofoil Flutter via Neural-Network-Based Adaptive Nonlinear Optimal Control. (Thesis). University of Adelaide. Retrieved from http://hdl.handle.net/2440/123093

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Tang, Difan. “Active Suppression ofAerofoil Flutter via Neural-Network-Based Adaptive Nonlinear Optimal Control.” 2019. Thesis, University of Adelaide. Accessed March 03, 2021. http://hdl.handle.net/2440/123093.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Tang, Difan. “Active Suppression ofAerofoil Flutter via Neural-Network-Based Adaptive Nonlinear Optimal Control.” 2019. Web. 03 Mar 2021.

Vancouver:

Tang D. Active Suppression ofAerofoil Flutter via Neural-Network-Based Adaptive Nonlinear Optimal Control. [Internet] [Thesis]. University of Adelaide; 2019. [cited 2021 Mar 03]. Available from: http://hdl.handle.net/2440/123093.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Tang D. Active Suppression ofAerofoil Flutter via Neural-Network-Based Adaptive Nonlinear Optimal Control. [Thesis]. University of Adelaide; 2019. Available from: http://hdl.handle.net/2440/123093

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Louisiana State University

23. Guzzardo, Carla Ann. Optimal actuation in active vibration control using pole-placement.

Degree: PhD, Mechanical Engineering, 2012, Louisiana State University

URL: etd-10302012-133755 ; https://digitalcommons.lsu.edu/gradschool_dissertations/1504

► The purpose of this study was to find and demonstrate a method of optimal actuation in a mechanical system to control its vibration response. The… (more)

▼ The purpose of this study was to find and demonstrate a method of optimal actuation in a mechanical system to control its vibration response. The overall aim is to develop an active vibration control method with a minimum control effort, allowing the smallest actuators and lowest control input. Mechanical systems were approximated by discrete masses connected with springs and dampers. Both numerical and analytical methods were used to determine the optimum force selection vector, or input vector, to accomplish the pole placement, finding the optimal location of actuators and their relative gain so that the control effort is minimized. The problem was of finding the optimal input vector of unit norm that minimizes the norm of the control gain vector. The methods of pole placement and partial pole placement were introduced, and used to solve various problems, including the active natural frequency modification problem associated with resonance avoidance in undamped systems, and the single-input-multiple-output pole assignment problem for second order systems. Both full and limited controllability were addressed. During the numerical analysis, it was discovered that the system is uncontrollable if a control input vector is chosen that is mathematically orthogonal to an eigenvector associated with a reassigned eigenvalue. Conversely, the optimal input vector was discovered to be mathematically parallel to an eigenvector. This was proven analytically through mathematical proofs and demonstrated with various examples. Simulations were performed in MATLAB and Maple to verify the results numerically. An example using realistic units was developed to show the order of magnitude improvement expected by using this method of optimization. All initial conditions and system parameters were held the same, but the input vector was changed. The optimal input vector provided an order of magnitude improvement over an evenly distributed input vector. The principal conclusion was that by choosing a state feedback input vector that is mathematically parallel to the eigenvector associated with the open-loop eigenvalue to be reassigned, or in the case of multiple assignments, in the subspace of the eigenvectors, the control effort to accomplish pole placement can be reduced to its minimal value.

Subjects/Keywords: vibration; state feedback control; pole assignment; partial pole placement; resonance avoidance; minimization of control effort; optimal actuation; active vibration control

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APA (6^th Edition):

Guzzardo, C. A. (2012). Optimal actuation in active vibration control using pole-placement. (Doctoral Dissertation). Louisiana State University. Retrieved from etd-10302012-133755 ; https://digitalcommons.lsu.edu/gradschool_dissertations/1504

Chicago Manual of Style (16^th Edition):

Guzzardo, Carla Ann. “Optimal actuation in active vibration control using pole-placement.” 2012. Doctoral Dissertation, Louisiana State University. Accessed March 03, 2021. etd-10302012-133755 ; https://digitalcommons.lsu.edu/gradschool_dissertations/1504.

MLA Handbook (7^th Edition):

Guzzardo, Carla Ann. “Optimal actuation in active vibration control using pole-placement.” 2012. Web. 03 Mar 2021.

Vancouver:

Guzzardo CA. Optimal actuation in active vibration control using pole-placement. [Internet] [Doctoral dissertation]. Louisiana State University; 2012. [cited 2021 Mar 03]. Available from: etd-10302012-133755 ; https://digitalcommons.lsu.edu/gradschool_dissertations/1504.

Council of Science Editors:

Guzzardo CA. Optimal actuation in active vibration control using pole-placement. [Doctoral Dissertation]. Louisiana State University; 2012. Available from: etd-10302012-133755 ; https://digitalcommons.lsu.edu/gradschool_dissertations/1504

24. Jiménez, Samuel. Internal sensing and actuation topologies for active rotors.

Degree: PhD, 2017, University of Bath

URL: https://researchportal.bath.ac.uk/en/studentthesis/internal-sensing-and-actuation-topologies-for-active-rotors(4acb1c03-dc31-4571-a525-7b4c82280650).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.715252

► Active control constitutes the state of the art in vibration management in rotating machines. However, existing designs are impractical and costly, and hence not yet… (more)

▼ Active control constitutes the state of the art in vibration management in rotating machines. However, existing designs are impractical and costly, and hence not yet widely applied. The goal of the research reported here was to develop a design which would allow the implementation of active technology in a wider range of rotating machine applications. Thus, this study focuses on a novel active rotor topology, consisting of a hollow rotor with internally mounted sensors and actuators. This layout provides greater freedom to select the sensor and actuator positions along the rotor, and naturally protects the devices from harsh working environments. The research was structured according to four themes. Firstly, the concept feasibility was explored by constructing a fully functioning prototype. MEMS accelerometers and mass balancer actuators were mounted in an assembled rotor, together with a microcontroller and radio unit to enable wireless transmission of data. Secondly, the behaviour of MEMS accelerometers in a rotating frame of reference was studied. An output model was derived and applied to the study of whirl orbits and transient vibration. Further, techniques were developed to extract mean displacement and angular velocity information from the sensor signals. An analysis of potential sources of measurement error was conducted, and methods for their mitigation devised. The third theme focused on developing active vibration control techniques suitable for use with active rotors. The core of this work is the development and successful implementation of a non a priori method, Algorithmic Direct Search Control. This technique enables vibration to be minimised without knowledge of the system characteristics, by applying a direct search optimisation technique as a control law. Finally, the combination of active rotors and Active Magnetic Bearings was considered to tackle the problem of sensor/actuator non-collocation. The challenge of levitating a rotor on AMBs using only internal accelerometers was approached via integration-based displacement information extraction, to exploit existing PID controllers. This method proved unfeasible in practice, but valuable lessons were derived from the study. The key finding of this work is that active rotor technology is versatile, cost-effective, powerful and feasible. As such, it offers great potential as a route to achieving a more practical and generalised implementation of active control technology in rotating machinery.

Subjects/Keywords: 621.8; rotordynamics; accelerometers; Active control; Vibration control; Magnetic bearings

10 more images…

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APA (6^th Edition):

Jiménez, S. (2017). Internal sensing and actuation topologies for active rotors. (Doctoral Dissertation). University of Bath. Retrieved from https://researchportal.bath.ac.uk/en/studentthesis/internal-sensing-and-actuation-topologies-for-active-rotors(4acb1c03-dc31-4571-a525-7b4c82280650).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.715252

Chicago Manual of Style (16^th Edition):

Jiménez, Samuel. “Internal sensing and actuation topologies for active rotors.” 2017. Doctoral Dissertation, University of Bath. Accessed March 03, 2021. https://researchportal.bath.ac.uk/en/studentthesis/internal-sensing-and-actuation-topologies-for-active-rotors(4acb1c03-dc31-4571-a525-7b4c82280650).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.715252.

MLA Handbook (7^th Edition):

Jiménez, Samuel. “Internal sensing and actuation topologies for active rotors.” 2017. Web. 03 Mar 2021.

Vancouver:

Jiménez S. Internal sensing and actuation topologies for active rotors. [Internet] [Doctoral dissertation]. University of Bath; 2017. [cited 2021 Mar 03]. Available from: https://researchportal.bath.ac.uk/en/studentthesis/internal-sensing-and-actuation-topologies-for-active-rotors(4acb1c03-dc31-4571-a525-7b4c82280650).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.715252.

Council of Science Editors:

Jiménez S. Internal sensing and actuation topologies for active rotors. [Doctoral Dissertation]. University of Bath; 2017. Available from: https://researchportal.bath.ac.uk/en/studentthesis/internal-sensing-and-actuation-topologies-for-active-rotors(4acb1c03-dc31-4571-a525-7b4c82280650).html ; https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.715252

Georgia Tech

25. Fujioka, Daichi. Input-shaped model reference control for flexible systems.

Degree: PhD, Mechanical Engineering, 2016, Georgia Tech

URL: http://hdl.handle.net/1853/60107

► Heavy-lifting machines, such as cranes and aerial lifts, are widely used to perform material handling in various applications. However, their operational efficiency and throughput are… (more)

▼ Heavy-lifting machines, such as cranes and aerial lifts, are widely used to perform material handling in various applications. However, their operational efficiency and throughput are degraded by the inherent flexible dynamics of the systems. For example, cranes carrying a payload can experience large payload swings, and aerial lifts extending or rotating their arms can vibrate due to the flexibility in the arms and the joints. The oscillation problems are further complicated by complex nonlinear dynamics, time-varying parameters, and lack of full state information. This thesis investigates a simple and robust control method that improves the operation of flexible systems, even in the absence of an accurate system model and sensing. The goal is achieved via the combination of input shaping and model reference control (MRC). The input-shaped model reference control (IS-MRC) design compensates for the weakness of input shaping with the MRC scheme, while input shaping improves the performance of MRC by modifying the reference command. The benefits of the proposed controller design include increased robustness against plant uncertainties and parameter estimation errors, while also achieving good vibration suppression and control effort reduction. The IS-MRC design is first developed for controlling a crane with a single-pendulum payload. The state space representation and parameter values of the reference model and plant are developed. A Lyapunov control law with asymptotic stability and the corresponding input shaper design are derived. Numerical simulations reveal that IS-MRC contributes to reducing the control effort magnitude for large ranges of system parameter values. The robustness of IS-MRC to parameter estimation errors is analyzed. The performance of IS-MRC in state tracking, oscillation suppression, and control effort reduction is verified via experiments. The IS-MRC design is further tested on a nonlinear double-pendulum payload. The double-pendulum dynamics are derived and the state space representation of the the plant is obtained. The possible ranges of oscillation modes are calculated, and multi-mode input shapers are designed to suppress the range oscillations. To address practical implementation issues, a linear single-pendulum is used as the reference model. A Lyapunov control law using only the first mode states of the plant is derived. The robustness of various IS-MRC designs are tested via numerical simulations and experiments. The robustness to the plant modeling error is analyzed by inducing error in the estimated plant natural frequency. The robust IS-MRC effectively suppresses the hook and payload oscillations. The trade-off to effective suppression, however, is a slower motion. The thesis then extends the study to improve the performance of IS-MRC. An optimized input-shaped model reference control (OIS-MRC) scheme is developed to obtain the optimal combination of input shaping and model reference control. An optimization technique is used to concurrently design the controller parameters that… Advisors/Committee Members: Singhose, William (advisor), Ume, Charles (committee member), Ueda, Jun (committee member), Vaughan, Joshua (committee member), Rogers, Jonathan (committee member).

Subjects/Keywords: Input shaping; Model reference control; Crane; Vibration control; Human operator study

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APA (6^th Edition):

Fujioka, D. (2016). Input-shaped model reference control for flexible systems. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/60107

Chicago Manual of Style (16^th Edition):

Fujioka, Daichi. “Input-shaped model reference control for flexible systems.” 2016. Doctoral Dissertation, Georgia Tech. Accessed March 03, 2021. http://hdl.handle.net/1853/60107.

MLA Handbook (7^th Edition):

Fujioka, Daichi. “Input-shaped model reference control for flexible systems.” 2016. Web. 03 Mar 2021.

Vancouver:

Fujioka D. Input-shaped model reference control for flexible systems. [Internet] [Doctoral dissertation]. Georgia Tech; 2016. [cited 2021 Mar 03]. Available from: http://hdl.handle.net/1853/60107.

Council of Science Editors:

Fujioka D. Input-shaped model reference control for flexible systems. [Doctoral Dissertation]. Georgia Tech; 2016. Available from: http://hdl.handle.net/1853/60107

Penn State University

26. Trowbridge, Michael. Fluidic Flexible Matrix Composite Damped Vibration Absorbers for Stiff-Inplane Hingeless Rotor Blades.

Degree: 2019, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/16983mjt5370

► Stiff-inplane hingeless rotor blades are integral to modern high-speed coaxial rotorcraft, such as the S-97 Raider and SB>1 Defiant. These rotor blades undergo little inplane… (more)

▼ Stiff-inplane hingeless rotor blades are integral to modern high-speed coaxial rotorcraft, such as the S-97 Raider and SB>1 Defiant. These rotor blades undergo little inplane deformation near the blade root, making traditional lag damper solutions ineffective. Fluidic Flexible Matrix Composite (F2MC) tubes are compelling candidates for a passive inplane vibration treatment due to their demonstrated ability to reduce structural vibrations in stiff structures. This work presents the modeling, design, and experimental testing of a new, dual-tube coupled F2MC damped vibration absorber for use on stiff-inplane hingeless rotor blades. The proposed device is modeled on a full-scale stiff-inplane (1.4/rev) hingeless rotor blade based on the Sikorsky X2-TD. Multiple tube configurations are explored, and the model predicts an increase of the first-chordwise mode’s damping ratio from a baseline of 2% critical damping to up to 15.1% critical damping. Parametric studies are conducted, and the coupled-tube configuration is compared to a single F2MC tube with an accumulator. A 4.5-foot hingeless rotor blade with integrated F2MC damped vibration absorbers is designed, built, and tested to demonstrate the concept and validate model predictions. The inplane dynamics are captured in the time-domain and frequency-domain for the blade tip displacement, blade root bending strain, and internal fluid pressure for multiple treatment designs, operating conditions, and loading conditions. Model predictions closely correlate with experimental results, which demonstrate an increase of the first mode’s damping ratio from 0.5% for the untreated blade to up to 10.3% when treated with the F2MC damped vibration absorber. The treatment performs equally well under dual-frequency loading conditions with large 1/rev loads. A remote motor-controlled excitation method is designed and tested for use in future testing of the small-scale hingeless blade in a rotating environment. Advisors/Committee Members: Christopher D. Rahn, Thesis Advisor/Co-Advisor, Edward C. Smith, Thesis Advisor/Co-Advisor, Eric R. Marsh, Committee Member, Daniel C. Haworth, Committee Member.

Subjects/Keywords: F2MC; damped vibration absorber; fluidic flexible matrix composite; helicopter; rotorcraft; structural dynamics; vibration absorber; rotor blade; vibration control; stiff-inplane

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APA (6^th Edition):

Trowbridge, M. (2019). Fluidic Flexible Matrix Composite Damped Vibration Absorbers for Stiff-Inplane Hingeless Rotor Blades. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/16983mjt5370

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Trowbridge, Michael. “Fluidic Flexible Matrix Composite Damped Vibration Absorbers for Stiff-Inplane Hingeless Rotor Blades.” 2019. Thesis, Penn State University. Accessed March 03, 2021. https://submit-etda.libraries.psu.edu/catalog/16983mjt5370.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Trowbridge, Michael. “Fluidic Flexible Matrix Composite Damped Vibration Absorbers for Stiff-Inplane Hingeless Rotor Blades.” 2019. Web. 03 Mar 2021.

Vancouver:

Trowbridge M. Fluidic Flexible Matrix Composite Damped Vibration Absorbers for Stiff-Inplane Hingeless Rotor Blades. [Internet] [Thesis]. Penn State University; 2019. [cited 2021 Mar 03]. Available from: https://submit-etda.libraries.psu.edu/catalog/16983mjt5370.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Trowbridge M. Fluidic Flexible Matrix Composite Damped Vibration Absorbers for Stiff-Inplane Hingeless Rotor Blades. [Thesis]. Penn State University; 2019. Available from: https://submit-etda.libraries.psu.edu/catalog/16983mjt5370

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Penn State University

27. Zhu, Bin. Modeling, Design, and Experimental Testing of Integrated Fluidic Flexible Matrix Composite Structures.

Degree: 2014, Penn State University

URL: https://submit-etda.libraries.psu.edu/catalog/22091

► Fluidic Flexible Matrix Composites (F2MCs) consist of a highly anisotropic FMC laminate that encloses a working fluid. The FMC laminate is basically a composite shell… (more)

▼ Fluidic Flexible Matrix Composites (F2MCs) consist of a highly anisotropic FMC laminate that encloses a working fluid. The FMC laminate is basically a composite shell that has reinforcements orientated at a particular angle with respect to the longitudinal axis. F2MC tubes have been shown to provide actuation, stiffness change, and vibration reduction in applications that require isolated tubes or multiple tubes embedded in a soft matrix. Structural applications, however, often require stiff and strong materials. The objective of this research is to integrate relatively soft F2MC tubes into rigid host structures, by either embedding or bonding, such that the F2MC integrated structures can have tunable shape, stiffness, fluid pumping, vibration damping, or vibration absorption characteristics. First, we explore the functionality of F2MC tubes embedded into a stiff matrix. The geometry and anisotropy of the tube can be tailored for either highly leveraged fluid pumping under mechanical deformation or highly leveraged stiffness change by preventing fluid flow into or out of the tube. A bilayer analytical model is developed using Lekhnitskii’s solution for an anisotropic tube under axial and pressure loading. The analysis shows a confining effect of the surrounding rigid matrix on the performance of F2MC tubes. With tailoring of the tube wall thickness (thick) and wind angle (near-axial), however, F2MC tubes can pump 250 times more fluid than a piston of the same diameter. Furthermore, axial stiffness can be increased by a factor of 2.2 when fluid flow is prevented. Secondly, the actuation performance of F2MC tubes embedded in structural media is investigated. The unit cell models examined are cylindrical and bi-layer with the inner layer being a thick walled F2MC tube and the outer layer representing the surrounding rigid composite and composed of either homogeneous epoxy or a second FMC layer made with stiffer matrix material. The analytical models are validated using ABAQUS. The analytical results show that actuation performance is generally reduced compared to that of an isolated F2MC tube due to the radial and longitudinal constraints. Free strain is generally two orders of magnitude smaller for an F2MC tube in structural media, requiring higher actuation pressures for bi-layer F2MC structures. The blocking force of F2MC in either epoxy or composite is roughly an order of magnitude smaller than that of an isolated F2MC tube. Thirdly, we propose damping the vibration of a cantilever beam by bonding multiple F2MC tubes to the beam and using the strain induced fluid pumping to dissipate energy. Transverse beam vibration strains the F2MC tube and generates fluid flow through an energy dissipating orifice. An optimally sized orifice maximizes energy dissipation, greatly reducing the resonant peaks and increasing modal damping. An analytical model is developed based on Euler-Bernoulli beam theory and Lekhnitskii’s solution for anisotropic layered tubes. Using miniature tubes, a laboratory-scale F2MC-integrated beam… Advisors/Committee Members: Christopher Rahn, Committee Chair/Co-Chair, Charles E Bakis, Committee Chair/Co-Chair, Martin Wesley Trethewey, Committee Member, Alok Sinha, Committee Member, George A Lesieutre, Special Member.

Subjects/Keywords: Vibration Control; Fluidic Flexible Matrix Composite; Passive Vibration Suppression; Harmonic Resonance; Damping Treatment

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

APA (6^th Edition):

Zhu, B. (2014). Modeling, Design, and Experimental Testing of Integrated Fluidic Flexible Matrix Composite Structures. (Thesis). Penn State University. Retrieved from https://submit-etda.libraries.psu.edu/catalog/22091

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Zhu, Bin. “Modeling, Design, and Experimental Testing of Integrated Fluidic Flexible Matrix Composite Structures.” 2014. Thesis, Penn State University. Accessed March 03, 2021. https://submit-etda.libraries.psu.edu/catalog/22091.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Zhu, Bin. “Modeling, Design, and Experimental Testing of Integrated Fluidic Flexible Matrix Composite Structures.” 2014. Web. 03 Mar 2021.

Vancouver:

Zhu B. Modeling, Design, and Experimental Testing of Integrated Fluidic Flexible Matrix Composite Structures. [Internet] [Thesis]. Penn State University; 2014. [cited 2021 Mar 03]. Available from: https://submit-etda.libraries.psu.edu/catalog/22091.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Zhu B. Modeling, Design, and Experimental Testing of Integrated Fluidic Flexible Matrix Composite Structures. [Thesis]. Penn State University; 2014. Available from: https://submit-etda.libraries.psu.edu/catalog/22091

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Georgia Tech

28. Holdhusen, Mark Horner. The state-switched absorber used for vibration control of continuous systems.

Degree: PhD, Mechanical Engineering, 2005, Georgia Tech

URL: http://hdl.handle.net/1853/6850

► A State-Switched Absorber (SSA) is a device capable of instantaneously changing its stiffness, thus it can switch between resonance frequencies, increasing its effective bandwidth as… (more)

Subjects/Keywords: State switching; Vibration absorber; Vibration control

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

APA (6^th Edition):

Holdhusen, M. H. (2005). The state-switched absorber used for vibration control of continuous systems. (Doctoral Dissertation). Georgia Tech. Retrieved from http://hdl.handle.net/1853/6850

Chicago Manual of Style (16^th Edition):

Holdhusen, Mark Horner. “The state-switched absorber used for vibration control of continuous systems.” 2005. Doctoral Dissertation, Georgia Tech. Accessed March 03, 2021. http://hdl.handle.net/1853/6850.

MLA Handbook (7^th Edition):

Holdhusen, Mark Horner. “The state-switched absorber used for vibration control of continuous systems.” 2005. Web. 03 Mar 2021.

Vancouver:

Holdhusen MH. The state-switched absorber used for vibration control of continuous systems. [Internet] [Doctoral dissertation]. Georgia Tech; 2005. [cited 2021 Mar 03]. Available from: http://hdl.handle.net/1853/6850.

Council of Science Editors:

Holdhusen MH. The state-switched absorber used for vibration control of continuous systems. [Doctoral Dissertation]. Georgia Tech; 2005. Available from: http://hdl.handle.net/1853/6850

University of Tennessee – Knoxville

29. Guan, Peng. Parametric Instability and Vibration Suppression of Planetary Gear Transmissions Supported on Boundary Struts.

Degree: 2016, University of Tennessee – Knoxville

URL: https://trace.tennessee.edu/utk_graddiss/4095

► This dissertation explores the effects of discrete boundary strut properties on stability and vibration of the planetary gear transmission (PGT) driveline systems. Also, a robust… (more)

▼ This dissertation explores the effects of discrete boundary strut properties on stability and vibration of the planetary gear transmission (PGT) driveline systems. Also, a robust output feedback control law is developed to actively control the PGT system vibrations. To better obtain boundary strut properties, a light-weight boundary strut design was developed for two popular boundary strut configurations by considering yield stress, buckling, and local buckling constraints. To facilitate analysis and development of the active control law, a comprehensive analytical PGT driveline system with elastic ring model, including gyroscopic effect and rotating-frame damping, is developed. The equation of motion of the PGT driveline system is a periodically time-varying system, Floquet theory is utilized to solve the equations and determine the system stability numerically. After investigating the effects of boundary strut properties on the stability behaviors of the PGT driveline system over the operating speed range, a stability-based ring gear rim thickness design strategy is developed to accelerate the rim thickness design procedure. In this research, both passive and active vibration suppression methods are discussed. Harmonic balance method is used to solve the steady-state vibration responses of the PGT driveline system. For the study of passive vibration suppression for the PGT system excited by the interaction between moving planets, flexible ring gear, and the discrete boundary struts, the effects of boundary strut properties on maximum ring stress, planet bearing force, and tooth mesh force vibrations are investigated over the operating speed range. The analysis shows that by properly tuning the boundary strut properties, such as number, stiffness, and damping, some vibrations can be suppressed passively, and the worst case scenario would be when the number of boundary struts equals to the number of planets. Finally, a robust active output feedback control law is developed based on a reduced-order stationary elastic ring gear model with sensors installed. The steady-state performance of the active controllers designed based on different numbers of sensors is compared and discussed. The results show that with enough sensors, the active controller can effectively suppress the vibrations transmitted through boundary struts to the helicopter frame.

Subjects/Keywords: parametric instability; planetary gear transmission; vibration suppression; active vibration control; rotordynamics; Acoustics, Dynamics, and Controls

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

APA (6^th Edition):

Guan, P. (2016). Parametric Instability and Vibration Suppression of Planetary Gear Transmissions Supported on Boundary Struts. (Doctoral Dissertation). University of Tennessee – Knoxville. Retrieved from https://trace.tennessee.edu/utk_graddiss/4095

Chicago Manual of Style (16^th Edition):

Guan, Peng. “Parametric Instability and Vibration Suppression of Planetary Gear Transmissions Supported on Boundary Struts.” 2016. Doctoral Dissertation, University of Tennessee – Knoxville. Accessed March 03, 2021. https://trace.tennessee.edu/utk_graddiss/4095.

MLA Handbook (7^th Edition):

Guan, Peng. “Parametric Instability and Vibration Suppression of Planetary Gear Transmissions Supported on Boundary Struts.” 2016. Web. 03 Mar 2021.

Vancouver:

Guan P. Parametric Instability and Vibration Suppression of Planetary Gear Transmissions Supported on Boundary Struts. [Internet] [Doctoral dissertation]. University of Tennessee – Knoxville; 2016. [cited 2021 Mar 03]. Available from: https://trace.tennessee.edu/utk_graddiss/4095.

Council of Science Editors:

Guan P. Parametric Instability and Vibration Suppression of Planetary Gear Transmissions Supported on Boundary Struts. [Doctoral Dissertation]. University of Tennessee – Knoxville; 2016. Available from: https://trace.tennessee.edu/utk_graddiss/4095

University of Texas – Austin

30. -2534-3566. The effect of well path, tortuosity and drillstring design on the transmission of axial and torsional vibrations from the bit and mitigation control strategies.

Degree: PhD, Petroleum Engineering, 2018, University of Texas – Austin

URL: http://hdl.handle.net/2152/65223

► As well designs become increasingly complicated, a complete understanding of drillstring vibrations is key to maximize drilling efficiency, to reduce drillstring dysfunction and to minimize… (more)

▼ As well designs become increasingly complicated, a complete understanding of drillstring vibrations is key to maximize drilling efficiency, to reduce drillstring dysfunction and to minimize drillstring, tool, and borehole damage. Torque and drag models exist that seek to quantify the effects of borehole inclination and tortuosity on static friction along the drillstring; however, the effects on dynamic friction remains poorly understood. This dissertation begins with a review of the past fifty years of work on drillstring dynamics models, an overview of the proposed control strategies and a summary deployed vibration mitigation applications within the drilling industry. Derivations from first principles of a series of computationally efficient axial and torsional drillstring models in both the frequency and time domains are then presented and verified with field data. The transfer matrix approach is used to predict the severity of axial vibrations along the drillstring and is verified using a series of case studies using field data. Harmonic axial vibrations within drillstrings are either induced intentionally, in the case of axial oscillation tools midway along the drillstring, or unintentional, in the case of bit bounce. Two case studies of bit bounce are first evaluated to ensure model validity for a harmonic excitation at a the bit and the model is found to accurately predict bit bounce based on surface rotation rates. Induced axial oscillations, generated by axial oscillation tools, are then investigated to quantify friction reduction and drilling efficiency improvements. Optimal placement is found to depend on wellbore geometry, but is usually restricted to periodic regions of the drillstring. These optimizations are then verified using field trials and suggest that improved placement can result in 20% or more reduction in friction along the drillstring. Two applications of torsional drillstring vibrations are then investigated – stick slip mitigation and drillstring imaging. The time domain form of the torsional drillstring model is used first to evaluate the effectiveness of three types of top drive controllers – stiff controllers, tuned PI controllers and impedance matching controllers – in mitigating stick slip oscillations. Then, the transfer matrix method is applied to evaluate the effect of wellbore geometry on drillstring mobility to conclude that higher order modes of stick slip may become dominant in non-vertical wellbores. The feasibility of drillstring imaging using torsional signals from surface is then investigated to identify inputs and methods that show promise in three setups of varying complexity – a hanging beam, a laboratory drillstring model and a drilling rig. Two techniques show promise – white noise injection and model fitting of a step response – in identifying larger features, including drillstring length and BHA location. However, low sampling frequencies and low bandwidth inputs reduce the ability to image small features such as friction points along the wellpath. Advisors/Committee Members: Oort, Eric van (advisor), Açikmeşe, Behçet (advisor), Torres-Verdin, Carlos (committee member), Sepehrnoori, Kamy (committee member), Dykstra, Mark (committee member).

Subjects/Keywords: Drillstring dynamics; Drilling vibration; Drilling control systems; Axial oscillation tools; Vibration mitigation

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

APA (6^th Edition):

-2534-3566. (2018). The effect of well path, tortuosity and drillstring design on the transmission of axial and torsional vibrations from the bit and mitigation control strategies. (Doctoral Dissertation). University of Texas – Austin. Retrieved from http://hdl.handle.net/2152/65223

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Chicago Manual of Style (16^th Edition):

-2534-3566. “The effect of well path, tortuosity and drillstring design on the transmission of axial and torsional vibrations from the bit and mitigation control strategies.” 2018. Doctoral Dissertation, University of Texas – Austin. Accessed March 03, 2021. http://hdl.handle.net/2152/65223.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

MLA Handbook (7^th Edition):

-2534-3566. “The effect of well path, tortuosity and drillstring design on the transmission of axial and torsional vibrations from the bit and mitigation control strategies.” 2018. Web. 03 Mar 2021.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Vancouver:

-2534-3566. The effect of well path, tortuosity and drillstring design on the transmission of axial and torsional vibrations from the bit and mitigation control strategies. [Internet] [Doctoral dissertation]. University of Texas – Austin; 2018. [cited 2021 Mar 03]. Available from: http://hdl.handle.net/2152/65223.

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

Council of Science Editors:

-2534-3566. The effect of well path, tortuosity and drillstring design on the transmission of axial and torsional vibrations from the bit and mitigation control strategies. [Doctoral Dissertation]. University of Texas – Austin; 2018. Available from: http://hdl.handle.net/2152/65223

Note: this citation may be lacking information needed for this citation format:
Author name may be incomplete

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Open Access Theses and Dissertations