Nonlinear Aeroelastic Analyses and Structural Optimization in Aircraft Preliminary Design

Kurzfassung

The first part of this presentation gives an overview of the methods which are developed at the DLR Institute of Aeroelasticity for high fidelity aeroelastic simulations of High Aspect Ratio Wings (HARW). The benefits of computing maneuver and gust loads with CFD-based methods that account for aerodynamic nonlinearities due to shock motion and flow separation are highlighted. Especially for HARW, the local lift along the span shows high values close to the tip section, which are sensitive to flow separations both at quasi-steady maneuvers with high load factors but also in gust encounter with large gust amplitudes. The second part describes a framework that is used for the structural optimization of highly flexible jet transport aircraft wings with anisotropic materials. Nonlinearities due to geometrically large structural deformations are taken into account by a two-stage approach. First, the structure is optimized using linear aerodynamic and inertia loads as well as linear responses. In the second step, a series of geometrically nonlinear simulations is conducted to ensure that material strains are within the specified limits and no buckling of skins and spars occurs.