Stability investigation of a nonlinear self-adaptive camber airfoil

Abstract

© 2017, American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved.A passive self-adaptive camber airfoil proposes to reduce fatigue and increase durability of lifting surfaces lifetime. The airfoil stability is investigated in an incompressible flow using a two-dimensional four degree of freedom model on pitch, plunge, slat and flap angles, in which the kinematic of slat and flap are coupled by a linear relationship. Concentrated cubic structural restoring forces as effect of nonlinearities are considered. The aeroelastic governing equations are written and integrated numerically using a fourth order Runge-Kutta scheme for the time domain evaluations. The identification and stability analysis of limit cycle oscillations are evaluated in the time domain by the Duhamel formulation and compared to the quasi-steady approximation and a method in the frequency domain using describing functions combined with the Sherman-Morrison formula. Investigations revealed that system parameters and initial conditions are crucial for the system dynamic stability that could lead to basin of attractions of periodic motions, heteroclinic orbits, jump phenomena and chaos.