A robust flutter prediction technique is developed by coupling nominal analysis, ground vibration test (GVT), flight flutter test (FFT), uncertainty model updation and robust analysis using μ method to accurately predict the flutter boundary of aircraft in frequency domain. Here, uncertainties in both structural and unsteady aerodynamics parameters are modelled in a Linear Fractional Transformation (LFT) framework. The magnitude of structural uncertainty is estimated based on the difference in the natural frequencies observed between the experiment (GVT) and nominal analysis. Further, the magnitude of aerodynamic uncertainty is estimated using the model validation technique based on μ method considering the difference in the damping values between the experiment (FFT) and nominal analysis. Finally, robust flutter analyses are performed to estimate the robust flutter boundary of aircraft based on the obtained model validating uncertainty magnitudes. The present approach gives a good estimate of flutter boundary a priori using the updated aerodynamic uncertainty magnitude based on flight flutter test data. The present technique helps to improve the flight test efficiency during the certification of aircraft with reduced number of flight test points, saving time and costs of flight flutter tests.

Last updated on : 07-01-2022 01:46:57pm