Identification of limit-cycles for piecewise non-linear transonic aeroelastic systems

This paper describes a method of analysing aeroelastic systems with complex piecewise non-linear structural stiffness in the transonic regime. The technique employed in this paper utilises novel logarithmic and tanh functions to both represent discrete non-linearities and to act as a switch between different non-linear areas. The aerodynamic model used is generated using an eigenvalue realisation algorithm (ERA) which produces a reduced order model (ROM) from linearised Euler simulations. It is shown that techniques are ideally suited to use with continuation methods. Flutter boundaries and limit-cycle oscillations can then be rapidly identified with good accuracy.