10. Aeroelastic Analysis Using Ground Vibration Test Modes

To characterize the dynamics of an aircraft, ground vibration testing is necessary. Typically, this testing is used to obtain the aircraft’s modal characteristics, which are then used to correlate and update a finite element model, which in turn is used in an aeroelastic analysis. However, building a dynamics model may not be feasible in some situations (such as when a non-OEM third party modifies an older aircraft for a new purpose) due to a lack of detailed engineering data or due to the cost compared to the scope of the overall project. The ability to use properly scaled free-free experimental mode shapes as inputs to the aeroelastic analysis could eliminate the time and cost associated with building and correlating a finite element model.

This paper investigates the use of experimental ground vibration test data from an “iron bird” demonstration test article in aeroelastic analysis. Issues associated with the use of experimental mode shapes directly in a flutter analysis are discussed, including obtaining rigid body modes and generating mass-normalized mode shapes.