Liviu Librescu

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Determination of the nature of the critical flutter boundary (benign/catastrophic) and its control constitute important issues that can be addressed within the nonlinear formulation of lifting surface theory. The main attention of this paper consists in the development of a computational approach enabling one to get a better understanding on time-delayed(More)
In this paper, the problem of implications of time delay feedback control of a two-dimensional supersonic lifting surface on the flutter boundary and on its character, that is, benign or catastrophic, is addressed. In this context, the structural and aerodynamic nonlinearities are included in the aeroelastic governing equations. The model and the associated(More)
This paper addresses the problem of the determination of the subcritical aeroelastic response and flutter instability of nonlinear two-dimensional lifting surfaces in an incompressible flow-field via indiciai functions and Volterra series approach. The related aeroelastic governing equations are based upon the inclusion of structural and damping(More)
ly , The present study addresses the subcritical aeroelastic response of swept wings, in various flight speed regimes, to arbitrary time-dependent external l excitations. The methodology based on the concept of indicial functions is carried out in time and frequency l,,,m,, domains. As a result of this approach, the proper unsteady aerodynamic loads(More)
The problem of the determination of the subcritical aeroelastic response and flutter instability of nonlinear two-dimensional lifting surfaces in an incompressible flow-field via Volterra series approach is addressed. The related aeroelastic governing equations are based upon the inclusion of structural nonlinearities, of the linear unsteady aerodynamics(More)
This paper by Professor Liviu Librescu was scheduled to be published in the December 2007 issue of the Journal of Ship Research. Professor Librescu was tragically killed in the shootings at Virginia Tech in April. He heroically blocked the door to his classroom while his students jumped out the window. His actions saved all but one. Professor Librescu was a(More)
This paper is concerned with the linear/nonlinear aeroelastic control of 2-D supersonic lifting surfaces. Its goal is to provide the feedback control mechanism enabling one to enlarge the flight envelope by increasing the flutter speed, and also to control the character, benign/catastrophic of the flutter instability boundary. Structural and aerodynamic(More)
In recent years, combat aircraft with external stores have experienced a decrease in their mission capabilities due to lack of robustness of the current passive wing/store flutter suppression system to both structured as well as unstructured uncertainties. The research program proposed here is to investigate the feasibility of using a piezoceramic wafer(More)
Vibration and stability feedback control of a robotic manipulator modeled as a cantilevered thin-walled beam carrying a spinning rotor at its tip is investigated. The control is achieved via incorporation of adaptive capabilities that are provided by a system of piezoactuators, bonded or embedded into the host structure. Based on converse piezoelectric(More)