Mitigation of flutter vibration using embedded shape memory alloys

Abstract

Aeroelastic flutter is a major concern for designers of planes, boats, turbines and other systems that experience aerodynamic loading. The typically undesirable phenomenon can cause aircraft instability, high cycle fatigue, excess noise, and in some cases catastrophic failure. This research aims to quantify the effect of embedded shape memory alloys (SMA) as an active suppression system to mitigate vibrations induced by aeroelastic flutter through an experimental investigation. A silicone plate with embedded SMA wire was designed. A subsonic wind tunnel was utilized to actuate flutter vibration. Control samples were created using the same dimensions and silicone material. One control sample contained embedded aluminum wire while the other sample contained no embedded material. Frequencies at the tip of the fluttering plates were calculated using a Fast Fourier Transfer (FFT) at varying temperatures. Experiments resulted in an average natural frequency shift of 44.6% at the sample tip upon actuation of the SMA material. Two dimensional vibrational scanning tests revealed three vibration modes in the fluttering flags. A first bending mode revealed a tip amplitude decrease of 34.4% upon actuation of the embedded SMA material. A second bending mode revealed a tip amplitude decrease of 33.6%. A torsional mode revealed a tip amplitude decrease of 60.7%. The frequency of the embedded aluminum wire sample remained relatively constant at low and high temperatures, leading to the conclusion that the frequency shift of the SMA sample was a result of the shape memory effect.