Aircraft morphing systems: Elasticity of selected components and modelling issues

Morphing is an increasingly investigated topic in aeronautics due to the performance improvements brought by aerodynamic shapes adaptivity on large aircraft. Being aerodynamics mainly driven by geometry, a structure that can modify its shape may achieve tremendous capability enhancement, especially if its operating scenario is wide. However, the implementation of morphing structures leads to many issues that still need to be properly solved to make the technology fully operative in real application scenarios. For instance, additional DOFs generate systems with increased modal density and then with more complex aeroelastic behaviour, and premature onset of dynamic instabilities. The authors of the present paper have dealt with this problem in other publications, in cooperation with several colleagues, and interesting results are available in literature, to some extent. In this general framework, there are peculiar aspects that only recently have started to catch the attention of the scientific community. Among those, a particular one is the objective of the present work, referring to the numerical simulation strategy of adaptive devices. The kinematic system at the basis of a wide class of morphing structures is driven by an actuation chain, which gives an important contribution to the already cited aeroelastic behaviour. For safety-critical embedded subsystems, it is crucial to detect potential failures and predict their impacts since the early design stages. Now, kinematic components significantly affecting the structural dynamics, as torsion bars and bearings, are assumed rigid in the traditional simulation strategy. If such a concept may be supposed valid for standard layouts (as in the case of flap, ailerons and other moveable systems), it cannot be held for architectures integrating hundreds of those mechanical parts. This work addresses preliminary investigations on systematic analyses carried out on detailed simulations of selected components of aircraft morphing structures, trying to evaluate the effects of elasticity of bearings and hinged connections on the global dynamic response.