One special use of the modelling and sizing process is the design of an aircraft wing with direct utilisation of the aeroelastic constraints. The static and dynamic characteristics of a wing are designed so that objectives such as optimum performance with minimum weight are achieved. For this, the Institute’s own design and optimisation process was developed in cooperation with TU Delft in the project ‘Smart Fixed Wing Aircraft’ (SFWA). The objective is the analysis of the potential of unconventional laminates for the design of highly flexible wings. The flexibility of the wing is described with discrete stiffness matrices for finite elements over a selected area (see image above), which represent the global characteristics of the fibre-reinforced composite layers.
The stiffness distribution is then optimised for the given load condition so that the required constraints are fulfilled. An example from the SFWA project is shown below. Here, the resulting stiffness distributions for the skin of the wing of a commercial aircraft are illustrated, which can be achieved for the same starting configuration with different target functions and constraints. The objectives are minimal structural mass with a given rudder effectiveness, as well as optimum control surface effectiveness with a given maximum structural mass.
The specially developed optimisation algorithm ensures that the resulting stiffness and mass distribution for the wing can be achieved in production. The method also allows the composite layers for the production of a model to be derived in a post-processing stage.