Parametric structural modelling of fish bone active camber morphing aerofoils

Abstract

Camber morphing aerofoils have the potential to significantly improve the efficiency of fixed and rotary wing aircraft by providing significant lift control authority to a wing, at a lower drag penalty than traditional plain flaps. A rapid, mesh-independent and two-dimensional analytical model of the fish bone active camber concept is presented. Existing structural models of this concept are one-dimensional and isotropic and therefore unable to capture either material anisotropy or spanwise variations in loading/deformation. The proposed model addresses these shortcomings by being able to analyse composite laminates and solve for static two-dimensional displacement fields. Kirchhoff-Love plate theory, along with the Rayleigh-Ritz method, are used to capture the complex and variable stiffness nature of the fish bone active camber concept in a single system of linear equations. Results show errors between 0.5% and 8% for static deflections under representative uniform pressure loadings and applied actuation moments (except when transverse shear exists), compared to finite element method. The robustness, meshindependence and analytical nature of this model, combined with a modular, parameter-driven geometry definition, facilitate a fast and automated analysis of a wide range of fish bone active camber concept configurations. This analytical model is therefore a powerful tool for use in trade studies, fluid-structure interaction and design optimisation.

Numerically Efficient Three-Dimensional Fluid-Structure Interaction Analysis for Composite Camber Morphing Aerostructures

“…Previous work by the authors has advanced this aim through recent structural modeling work and prototype development. Recently developed structural models can predict the static structural behavior of the composite FishBAC [19,21] using a reduced number of Degrees of Freedom (DOFs) compared to Finite Element Method (FEM). Additionally, these structural models were used to design a composite FishBAC wind tunnel wing model [18].…”

“…The structural model used in this FSI routine is a discontinuous composite plate model based on Mindlin-Reissner Plate Theory, which was developed in previous work by the authors [19,21]. In this model, the FishBAC is conceptualised as a series of partitioned plates connected together, with a new plate added at every chordwise and spanwise change in stiffness of the structure (e.g.…”

“…Lastly, Q i j refers to the local stiffness of each composite ply, and it is dependent on the fibre angle orientation. More details on how the final energy expressions are derived can be found in Rivero et al [19,21].…”

“…To directly implement these polynomials, the physical plate's dimensions and coordinates need to be transformed to a normalized frame (i.e. (ζ, η) | (ζ, η) ∈ [−1, 1]) [19,21].…”

An analytical model for granular jamming beams with applications in morphing aerostructures

“…Rivero et al, have been working on varying the flexural stiffness of the FishBAC by using composites layups along the spine. The flexural stiffness of the camber can be tuned if different stacking sequence layups are being used; which can significantly affect the torque required for the actuator to withstand the aerodynamic loads [11]. The key underlying concept of this research is to incorporate an active stiffness material into the structure of the FishBAC, to allow it to soften during actuation/morphing and to then stiffen once in the desired shape to reduce the actuation effort required to maintain shape.…”