Vibration and aeroelastic tailoring of advanced composite plate-like lifting surfaces
Abstract
Modern flight vehicles are often designed to meet requirements of high structural and aerodynamic performance. One way to attain this objective is to implement the techniques of aeroelastic tailoring. In this work, the lifting surface of a fighter aircraft is structurally idealized as a composite laminated plate element. By modifying the interactions between the surface deformation modes (e.g. bending and twisting), the elastic properties of the anisotropic plate can be controlled to satisfy a specific design criterion. The study is aimed at the conceptual understanding of the the effect of elastic coupling upon the dynamic and aeroelastic behavior of a wing. The structural analysis is performed using the Rayleigh-Ritz method. A group of five non-dimensional parameters is identified to characterize the stiffness properties of a laminated plate. Three of these parameters measure the amount of elastic coupling present in the plate, and their influences on the vibration modes (natural frequencies and mode shapes) are evaluated in the vibration analysis. A scheme based on energy conservation is also devised to determine the participation of different fundamental modes in the vibratory motion. Aeroelastically, the coupling/decoupling of deformation modes can affect the flutter margin significantly. The aerodynamic performance evaluated in terms of the drag polar can also be enhanced or degraded depending upon the type and extent of structural deformations. The study shows that, without incurring any weight penalty, the performance of a lifting surface can be improved by tailoring for the optimal stiffness distribution. Based on the results obtained, some design guidelines were spelled out to build a more efficient wing.
Degree
Ph.D.
Advisors
Weisshaar, Purdue University.
Subject Area
Aerospace materials
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