The Aeroelastic Analysis of Thick Supersonic Fins with Torsional Freeplay

One of the most important challenging issues about the designing of the actuated parts of aerial vehicles e.g. controlling surfaces or advanced generic missile pin is freeplay. According to this phenomenon some nonlinear terms enter to the aeroelastic analyses. In the present paper, according to this importance, the aeroelastic instability of two dimensional fin with freeplay nonlinearity in pitching degree of freedom operating in supersonic and hypersonic flight speed regimes have been considered. Based on local piston theory the unsteady aerodynamic loads on each surfaces of the fin are calculated. Then, the structural dynamics model of the fin is obtained based on the Lagrange's equations of motion. The governing ODE equations are derived by combination of these aerodynamic and structure models of the fin. In addition, the effects of the structural nonlinearities are investigated in the obtained equations. These equations are solved by using of the Runge-Kutta scheme at different time’s domain. In the present simulation the effects of the torsional freeplay are studied for fins with various thicknesses and angle of attack, and responses involving limit cycle oscillation and chaotic motion are observed over these two parameters that characterizes the aeroelastic system. Present results show that the freeplay in the pitch as well as thickness and angle of attack have significant effects on the aeroelastic behavior of the fin in the supersonic and hypersonic flight speed regimes.

کلیدواژه ها:

supersonic fin ، aeroelastic instability ، local piston theory ، Limit Cycle Oscillations ، torsional freeplay