Dynamic Aeroelasticity Coupling Full Order Geometrically Nonlinear Structures and Full Order Linear Unsteady Aerodynamics - The Joined Wing Case

Abstract

In previous works the authors introduced a procedure for coupling linear modally reduced frequency-domain unsteady aerodynamic codes such as the Doublet Lattice and other panel methods with full order geometrically nonlinear flnite element structural models for the analysis of high aspect ratio wings, Joined Wings, and other conflgurations with important geometric structural nonlinearities. The present paper extends the previous work and introduces a procedure to couple the full order (rather than modal based) linear unsteady aerodynamics and full order geometrically nonlinear structures. The work also presents two options for aeroelastic dynamic analyses. In the flrst option dynamic simulations are performed from the start after the system is perturbed by initial conditions such as an an initial shape corresponding to an angle of attack. In the second option the dynamic aeroelastic simulation is performed after a steady state equilibrium, obtained using a nonlinear static aeroelastic simulation, is perturbed. Dynamic aeroelasticity in this case is studied as a perturbation about steady state static solutions. Such simulation methods have already been used to study Limit Cycle Oscillations in the cases such as plate-like wings. Here, the static and dynamic aeroelastic behavior of a realistic Joined Wing conflguration is analyzed in detail and the efiects of the stifiness of the joint and wings are discussed. Static divergence, linear and nonlinear ∞utter speed, and time domain simulations are performed. It is shown that the present methodology is a useful tool for the study of new complex geometrically nonlinear non-planar conflgurations when the unsteady aerodynamic forces involved are linear.