Title page for ETD etd-02212001-145056

Type of Document

Dissertation

Author

Ashour, Osama Naim

Author's Email Address

oashour@vt.edu

URN

etd-02212001-145056

Title

Nonlinear Control of Plate Vibrations

Degree

PhD

Department

Engineering Mechanics

Advisory Committee

Advisor Name	Title
Nayfeh, Ali H.	Committee Chair
Adjerid, Slimane	Committee Member
Ahmadian, Mehdi	Committee Member
Hajj, Muhammad R.	Committee Member
Mook, Dean T.	Committee Member

Keywords

Active Control
Piezoelectric Ceramics
Terfenol-D
Smart Materials
Saturation
Vibration Absorber

Date of Defense

2001-01-17

Availability

unrestricted

Abstract

A nonlinear active vibration absorber to control the vibrations of plates is investigated. The absorber is based on the saturation phenomenon associated with dynamical systems with quadratic nonlinearities and a two-to-one internal resonance. The technique is implemented by coupling a second-order controller with the plate's response through a sensor and an actuator. Energy is exchanged between the primary structure and the controller and, near resonance, the plate's response saturates to a small value.

Numerical as well as experimental results are presented for a cantilever rectangular plate. For numerical studies, finite-element methods as well as modal analysis are implemented. The commercially available software ABAQUS is used in the finite-element analysis together with a user-provided subroutine to model the controller. For the experimental studies, the plate is excited using a dynamic shaker. Strain gages are used as sensors, while piezoelectric ceramic patches are used as actuators. The control technique is implemented using a dSPACE digital signal processing board and a modeling software (SIMULINK). Both numerical and experimental results show that the control strategy is very efficient.

A numerical study is conducted to optimize the location of the actuators on the structure to maximize its controllability. In this regard, the control gain is maximized for the PZT actuators. Furthermore, a more general method is introduced that is based on a global measure of controllability for linear systems.

Finally, the control strategy is made adaptive by incorporating an efficient frequency-measurement technique. This is validated by successfully testing the control strategy for a non-conventional problem, where nonlinear effects hinder the application of the non-adaptive controller.

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