Introduction to Aircraft Aeroelasticity and Loads

20

Coupling of Structural and Aerodynamic Computational Models

The majority of the book so far has shown how aeroelastic and loads models can be developed using continuous approximation models of the structure and aerodynamics. Such an approach is fine for a simplistic aircraft representation; however, real-life structures are non-uniform and consequently are impossible to model accurately using approaches such as the Rayleigh-Ritz method. Instead, industry makes use of discrete approximation methods, such as finite elements (see Chapters 4 and 22), to produce detailed models of the aircraft structure. Similarly, numerical 3D panel methods, such as the vortex or doublet lattice methods (see Chapters 19 and 22), are often used to represent the aerodynamic forces acting on the aircraft. Although more sophisticated computational fluid dynamics (CFD) methods have been developed and used, for example, in performing accurate drag calculations and analysis in the transonic flight regime, the vast majority of the aeroelastic and loads analyses carried out in industry for commercial aircraft are performed using 3D panel methods (sometimes the panel methods are used to correct the rigid aircraft aerodynamics for flexible effects). Such an approach enables the structure and the aerodynamic models to be combined in a very efficient manner so that the static/dynamic aeroelastic and loads behaviour can be determined.

This chapter shows how potential flow aerodynamics can be combined with a structural ...