Experimental identification of rational function coefficients for time-domain flutter analysis

For time-domain flutter analysis, the frequency-dependent self-excited forces acting on the structure can be approximated in the Laplace domain by Rational Functions. The existing Rational Function Approximation (RFA) approach involves approximation of the experimentally obtained flutter derivatives. This motivated the formulation of a system identification technique (Experimental Extraction of Rational Function Coefficients or E2RFC) to directly extract the Rational Function Coefficients from wind tunnel testing. The current formulation requires testing of the section model at lesser number of velocities compared to the flutter-derivative approach which may lead to a significant reduction in time and resources associated with indirect extraction of Rational Functions from flutter derivatives. The methodology and algorithm of the E2RFC method, results of numerical simulation to test the method with two bridge deck sections, and experimentally obtained Rational Function Coefficients for one bridge deck section have been presented.