21st Congress of International Council of the Aeronautical Sciences, Melbourne, Australia, 13-18 September, 1998
Paper ICAS-98-7.7.4

NONLINEAR AEROELASTICITY AND FLIGHT DYNAMICS OF AIRCRAFT IN SUBSONIC FLOW

Patil M. J., Hodges D. H.
Georgia Institute of Technology, USA

Keywords: nonlinear, aeroelasticity,flight dynamics, aircraft, subsonic flow

Aeroelastic instabilities have always constrained the flight envelope and thus are considered important during design optimization. As we strive to reduce weight and raise performance levels using directional material, thus leading to an increasingly flexible aircraft, there is a need for reliable (less conservative yet accurate) analysis tools, which model all the important characteristics of the Fluid-Structure interaction problem. Such a model would be used in preliminary design and control synthesis. A theoretical basis has been established for a consistent analysis which takes into account, i) material anisotropy, ii) geometrical nonlinearities of the structure, iii) unsteady flow behavior, and iv) dynamic stall. The paper describes the formulation for aeroelastic analysis of aircraft with high-aspect-ratio wings. Preliminary results are presented and validated against the exact flutter speed of the "Goland" wing. Further results have been obtained which give insight into the effects of the structural and aerodynamic nonlinearities on the trim solution, flutter speed, amplitude of limit cycle oscillations, and effect of rigid body motion (flight dynamics).

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