Fluid/Structure-Interaction Analysis of the Fish-Bone-Active-Camber Morphing Concept

Abstract

A coupled, partitioned fluid/structure-interaction analysis is introduced for calculation of the deformed equilibrium shape, aerodynamic coefficients, and actuation requirements of the fish-bone-active-camber morphing concept. The fish-bone-active-camber concept is a high-authority morphing camber architecture with a broad range of applications, including fixed-wing aircraft, helicopters, wind turbines, and tidal-stream turbines. The low chordwise bending stiffness of the morphing structure, high stiffness of the tendon drive system, and the large changes in aerodynamic loading while morphing necessitate a coupled fluid/structure-interaction analysis for determination of the static equilibrium. An Euler–Bernoulli beam-theory-based analytical model of the structure is introduced and validated. Aerodynamic loads are found using the XFOIL software, which couples a potential-flow panel method with a viscous boundary-layer solver. Finally, the tendons are modeled as linear stiffness elements whose internal strains are found from the Euler–Bernoulli theory, and whose axial forces create bending moments on the spine at their discrete mounting points. Convergence of the fluid/structure-interaction code is stabilized through incorporation of relaxation parameters. The results for two chosen test cases are presented to give an insight into the mechanical and aerodynamic behavior of the fish-bone-active-camber concept.