Abstract: A novel method to determine the flutter speed and frequency i.e., the ground flutter simulation test, is proposed as a complementary method for traditional aeroelasticity tests. The key challenge of this new technique is the method to reduce the unsteady distributed aerodynamic forces to a few concentrated loads, and this is studied in this paper. The unsteady aerodynamic forces at the subsonic and supersonic Mach numbers of the wings are generated by using the subsonic doublet lattice method and piston theory. Subsequently the time-domain concentrated loads for testing are achieved by the use of the infinite plate spline method and the rational function approximation method. A genetic optimization is carried out to determine the best locations for the reduction of the unsteady aerodynamic forces, which takes the flutter related modes as the optimization objective. State-space modeling of the closed loop system is derived to observe the time-domain flutter results. The time-domain simulation flutter speeds have a very good agreement with the frequency-domain analysis results with an error which can be controlled to within 3%. The study demonstrates that the unsteady aerodynamic simulation method proposed in this paper can represent unsteady distributed aerodynamic forces for the wings and provid ecertain guidance for further ground flutter simulation studies.

Key words: aeroelasticity, flutter test, wing, unsteady aerodynamic force, simulation