Torsional control of thin-walled structures by piezoelectric actuators

The topics covered in this thesis are part of the feasibility study in using piezo active materials to modify torsional behavior of thin-walled opened and closed cross-section structural members. Both experimental and analytical methods were used in this investigation. The study began with the investigation of the electro-mechanical characteristics of a single piezo element, in particular the strain transfer mechanism. Then the study was extended to test a composite thin-walled, closed cross-section tube with piezo elements laminated to its walls. The effectiveness of piezo elements in damping torsional vibration was determined. As a part of the fundamental research, Vlasov's theory was used to calculate the amount of twist on a flat thin plate when it was actuated by piezoelectric elements bonded antisymmetrically to both of its surfaces. Also, smart elements based on the ACLD (Active Constrained Layer Damping) was evaluated as an alternative to piezoceramic elements for its potential in controlling structural vibrations.