Transient and limit-cycle simulation of a nonlinear aeroelastic system

The transient and steady-state response of an experimental aeroelastic system to initial displacements in each of its two degrees of freedom is modeled mathematically. The experimental results are from subsonic wind-tunnel tests performed on a 2-degree-of-freedom wing section with a structural, freeplay-type nonlinearity in the pitching degree of freedom. The system is modeled mathematically, and the equations of motion for the linear and three different nonlinear configurations are solved numerically to produce time histories, of the wing section displacements in pitch and plunge. Numerical data are compared to experimental results for both the transient and the steady-state stable and unstable limit-cycle oscillations of the experimental apparatus. The mathematical model is modified to reflect the mass distribution and frictional forces present in the experimental apparatus, and the model is validated for the system transient response by comparing numerical and experimental time histories.