Vibration control and design of composite cantilevers taking into account structural uncertainties and damage

Within this work a study of the vibrations of laminated composite cantilevers exhibiting structural uncertainties and damage is accomplished. The study is performed within both the Classical Lamination (CLT) and the First-order Transverse Shear Deformation Theories (FSDT). Upon comparing the natural frequencies and mode shapes obtained by both theories, the effects of transverse shear deformation will be emphasized. Other nonclassical effects as e.g. the bending-twist coupling and the warping restraint on the cantilevered structure are also considered. As passive techniques of vibration control, structural tailoring and optimization are implemented. To deal with structural uncertainties, a probabilistic discretization technique for the governing system is developed. Statistical properties of natural frequencies are obtained by means of a second-moment method and a first-order perturbation technique. Structural tailoring is reconsidered to reduce the sensitivity of the dynamic behavior to parameter uncertainties. Next, the damage effect on the structure is considered in the design process. As a result, the problem of the robustness of structures in the presence of damage is addressed. This work also deals with the active feedback control of cantilevered structural systems. An efficient control technique for continuous structures, namely modal control, is adopted and the control gain is obtained by an optimal control law. The comparison of controlled and uncontrolled dynamic responses is made between two models based on CLT and FSDT with emphasis on the influence played by transverse shear deformation and warping restraint.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Engineering Mechanics

Department dc:contributor.department

Engineering Mechanics

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1993

Author dc:creator

• Oh, Donghoon

Chair dc:contributor.committeechair

• Librescu, Liviu

Committee members dc:contributor.committeemember

• Cramer, Mark S.
• Meirovitch, Leonard
• Plaut, Raymond H.
• Thangjitham, Surot

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

etd-07282008-142024

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/39001