COMBINING ARBITRARY MODE EXTRACTION NUMERICAL CONTINUATION TO ANALYSE NON-LINEAR AEROELASTICITY

摘要

This paper describes a novel method by which BAE Systems, Farnborough, analyse non-linear aeroelastic problems. The method presented in this work is applicable to general structural non-linearities but is based on a specific Nimrod MRA4 case where combined failures could result in aileron output circuit stiffness being lost, leaving only non-linear damping to suppress flutter. The developed method uses a number of arbitrary aircraft modes extracted from a standard NASTRAN normal mode analysis and combines the mode shapes with numerical continuation methods to study non-linear dynamic phenomena. The application of numerical continuation to the problem of non-linear aeroelasticity has previously been restricted to simplified 2-D section test cases (Ref 1-4) but, by extracting arbitrary modes, this has opened up the field to allow full non-linear aircraft structures to be analysed rapidly in a modal form. The accuracy of the numerical continuation technique is established by comparing results with both fully non-linear and non-linear energy equivalenced (Ref 5) time simulations.