Nonlinear aerothermoelastic analysis of deployable control fin with actuator stiffness subjected to high-speed compressible flows

The current work investigates the aerothermoelastic behavior of control fins with nonlinear deployable joints connected to a nonlinear actuator. The fin is attached to a cylindrical body with a hemispherical bow, and the fin–body configuration is subjected to Mach 6 hypersonic flow with a nonzero angle of attack. A Navier–Stokes flow model-based computational fluid dynamics (CFD) solver is coupled to a finite element thermoelastic solver using mapping-based coupling technique. Diffusion function-based smoothing method is used for the CFD grid deformation. The fin is assumed to be connected to a finite stiffness actuator at the root, and the effects of actuator stiffness, actuator freeplay as well as freeplay at the deployable joint are investigated. Flow field, structural and thermal quantities are evaluated and reported for various fin configurations. A complex coupling between different modes of deformation is observed and it is shown that the actuator rotation or angle of attack, and hence torque, strongly depends on the actuator and joint freeplays. The obtained results indicate a significant increase in instabilities in the fin oscillation with increasing joint and root freeplay.