Application of the extra-modes method to the aeroelastic analysis of morphing wing structures

When dealing with the design of morphing wings, conventional structural arrangements are commonly replaced by innovative solutions enabling shape changes through actively controlled elasticity or mechanical systems. In both cases, no simplified rules coming from consolidated experiences may be invoked to guarantee that a specific design will be characterized by stable and sustainable aeroelastic response to external loads expected in service.A rational approach for the aeroelastic analysis of the structural arrangements is therefore recommended since the earliest design stage so that the maturation of unflyable solutions is naturally avoided.The extra-modes method is herein detailed as a dramatically efficient tool to accomplish this paramount task. The morphing device is treated as a substructure and the aircraft (A/C) as the basic system on which the device is installed. Substructure's contribute to the aeroelastic response of the global system is expressed in terms of generalized parameters pertinent to additional and strategically defined modes capturing the substructure dynamics. After recalling the general formulation of the method, two case studies are presented in order to show its great potential to rapidly appreciate the aeroelastic behavior of a given design, irrespective of the maturity level of the design itself.