The aeroelastic response of a wing section with a structural freeplay nonlinearity: An experimental investigation

Results are presented for subsonic wind tunnel experiments performed on a two-degree-of-freedom wing section with a structural, freeplay-type nonlinearity in the pitching degree of freedom. The experiments demonstrate the effect of the freeplay on the aeroelastic response, including the presence of limit cycle flutter for specific parameter combinations. The effects of variations in both freeplay length and frequency ratio of the underlying linear system are examined for both the damped and the limit cycle response. Time histories of the damped response are used to estimate frequency and damping values, and to predict critical flutter speeds. The amplitude and frequency of the LCO response is presented for three different freeplay lengths and five frequency ratios.