Influences of starting transients, aerodynamic definitions and boundary conditions on elastic and viscoelastic wing and panel flutter

Craig C. Merrett; Harry H. Hilton

Craig C. Merrett University of Illinois at Urbana-Champaign
Harry H. Hilton University of Illinois at Urbana-Champaign

Keywords: elastic and viscoelastic flutter, eigenvalues, integral-differential equations, lift- ing surfaces, necessary and sufficient flutter conditions, panels, unsteady flight velocities

Abstract

An analytical study is undertaken to ascertain the effects on elastic and viscoelastic flutter of (1) starting transients due to changes in flight velocity, (2) boundary conditions and (3) unsteady aerodynamic force definitions (spatial deflection derivatives). Lifting surface and panel flutter are considered in the steady-state velocity range after transient effects and varied boundary condition influences are also studied. In addition to the various unsteady aerodynamic theories, the effects due to the presence or absence of spatial deflection derivatives on pressure distributions are also examined. Necessary and sufficient conditions for the onset of flutter in the form of simple harmonic motion are also formulated and evaluated.