A Procedure for Flutter Analysis with Nonlinear Experimental Modal Parameters

Kurzfassung

GVT are conducted to identify structural modal models which are used afterwards either to validate an existing numerical model or to establish a mathematical substitute model for further analysis, e.g. as input for flutter analysis. The use of experimental substitute models is not based on modelling assumptions. However, the system identification methods applied to the test data are based on the assumptions of linear and time-invariant systems (LTI). Most often nonlinear effects are observed with aerospace structures in a GVT. This would also affect the results of flutter analysis and critical flutter speeds. However, considering nonlinear effects in the analysis model and subsequent nonlinear simulations might not be feasible shortly before the first flight. This work proposes a procedure to perform flutter analysis in time domain with a nonlinear mathematical substitute model, which can be derived from experimental data. A numerical model of a wing section is considered in this work to assess the presented approach. It is shown that LCOs with a fair agreement in amplitude and flight speed of LCO onset in comparison to the nonlinear simulation can be obtained.