Various Structural Approaches to Analyze an Aircraft with High Aspect Ratio Wings

Abstract

Aeroelastic analysis of an aircraft with a high aspect ratio-wing for medium altitude and long endurance capability was attempted in this thesis. In order to achieve such objective, various structural and aerodynamic models were adopted. The traditional approach has been based on an Euler-Bernoulli beam structural model. In addition to that, a geometrically non-linear beam model was adopted. The structural analysis results of the present beam models were obtained and later compared with those by three-dimensional NASTRAN finite element model. The relevant unsteady aerodynamic forces were acquired by two methods. First, a finite state dynamic inflow unsteady aerodynamics model was developed and evaluated. Second, ZAERO, which is based on the doublet-lattice method, was used. These two kinds of aerodynamic forces were compared, and applied to the foregoing flutter analysis. For instance, the structural mode shapes and natural frequencies from both the Euler-Bernoulli beam structural model and the three-dimensional finite element model were transferred to ZAERO, which used the DLM aerodynamics to estimate the flutter. Similarly, flutter prediction was conducted by combining the Euler-Bernoulli beam structural model and the finite state dynamic inflow unsteady aerodynamics. The next phase of the present research will deal with the analysis of the possible interaction between the rigid-body degrees of freedom and the aeroelastic modes.