Non-linear aerothermoelastic modeling and behavior of a double-wedge lifting surface

Abstract

The design of the re-entry space vehicles and high-speed aircraft structures requires special attention to the non-linear thermoelastic and aerodynamic instabilities. The thermal effects are important since temperature environment influences significantly the static and dynamic behaviors of flight structures in supersonic/hypersonic regimes. The dynamic behavior of a double-wedge lifting surface with combined freeplay and cubic stiffening structural nonlinearities in both plunging and pitching degrees-of-freedom (DOF) operating in supersonic/hypersonic flight speed regimes has been analyzed. In addition a third order piston theory aerodynamics (PTA) is used to evaluate the non-linear unsteady aerodynamic loads applied to the wing section. Loss of torsional stiffness that may be incurred by lifting surfaces subjected to axial stresses induced by aerodynamic heating is also considered. The aerodynamic heating effect is estimated based on the adiabatic wall temperature due to high speed airstreams. It is demonstrated that serious losses of torsional stiffness may occur in such lifting surfaces; the influence of various parameters such as flight condition, thickness ratio, freeplays and pitching stiffness nonlinearity are discussed.

Response of a three-degree-of-freedom wing with stiffness and aerodynamic nonlinearities at hypersonic speeds

“…The initial conditions had the effect of creating a chaotic response. The results presented here add to the work done where chaotic motion and limit cycle oscillations were predicted for a two-dimensional aerofoil with stiffness nonlinearities [15,33,38,50] or aerodynamic nonlinearities [2].…”

“…Lee and Tron [21] showed that loose control surfaces can be adequately represented via either a bilinear spring stiffness or a cubic nonlinearity, by modelling the LCOs seen in the CF-18 aircraft. A considerable amount of research has gone into investigating the aeroelastic response of an aerofoil with bilinear nonlinearities in either the plunge or pitch degrees of freedom [2,22,29,32,33,36], with limited research on three-dimensional aeroelastic models for high-speed application [3,4,23,30]. Free-play nonlinearities usually occur in the control surface [16], whereas the cubic stiffness comes mainly from the large amplitude oscillation of the flexible wing [19].…”