Postdoctoral position (2yrs) in mechanical engineering : Flutter control of flexible drone wings

Key words

Nonlinear dynamics, aeroelasticity, damping, vibration control, modelling, numerical analysis.

Context

Considering CREA anchorage in the military aeronautical environment, and its geographical location within the 701 air base, which gives it privileged access to experimental facilities, research work on the multidisciplinary design and use of UAVs is a major focus of its scientific project.

This postdoctoral research project is part of the so-called HALION project, carried out in collaboration with ISAE-SUPAERO and funded by the French Innovation Defense Agency. ISAE-SUPAERO plans to design and manufacture a high-altitude long endurance drone demonstrator (called HALE drone) powered mainly by solar energy. The resulting very flexible structure leads to many technical challenges. The objective of the HALION project is to study the possibility of using active and passive stabilization systems to mitigate the effects of flutter that is currently an important cause of flight range limitation. By adding passive dampers to the structure, it may be possible to control this instability at an acceptable low level of vibration and/or to push back its occurrence in the flight range.

In the work planned at CREA, the researcher will focus on the use of a structural nonlinear absorber to control the global vibrational amplitude. This type of method has shown its efficiency on simple models, but its integration in a structure showing geometric nonlinearities and under nonlinear aeroelastic loading is a real challenge.

Work to be done

The first step will be to develop a numerical simulator based on a relatively accurate structural model of the wing, considering both geometric nonlinearities and aeroelastic forces. The proposed developments will be built on previous work focused on nonlinear beam models [1]. The approach used is an extension of Hodges [2] twisted and pre-bent beam model that includes the warping of cross-sections. To extend this simulator to a HALE flight simulator, the main difficulty will be to integrate the predominant aeroelastic effects into the model (see [3]). A validation by comparison with the GEBTAero code [4] currently being developed at CREA will be done. It is also expected to collaborate with researchers from ISAE-SUPAERO in order to implement their development in terms of active control of flutter stabilization within the HALE simulator.

After validation of the structural model of the wing under aeroelastic loading, the potential contribution of nonlinear passive damping will be studied. The nonlinear physics involved will first have to be mastered (see [5] for example). Then, the nonlinear absorber will be integrated into the HALE simulator to perform parametric studies and investigate the influence of both the added mass and the increased damping capabilities on flutter control.

Publication of scientific articles highlighting the innovative results is also expected.

[1] Di Palma, N., Chouvion, B. and Thouverez, F., 2022. https://hal.archives-ouvertes.fr/hal-03353678

[2] Hodges, D.H., Dowell, E.H., 1974. https://ntrs.nasa.gov/citations/19750005242

[3] Peters, D. A., Karunamoorthy, S., and Cao, W. M., 1995. https://doi.org/10.2514/3.46718

[4] Kirsch, B., Montagnier, O., Bénard, E. and Faure, T.M., 2020. https://doi.org/10.1016/j.jfluidstructs.2020.102930

[5] Y. Starosvetsky, O. V. Gendelman, 2009. https://doi.org/10.1016/j.jsv.2009.02.052