Modal approach in the fluid-structure interaction in aerospace

The paper contains examples of computational analyses based on modal modelling of the structural motion. This approach is typical for the investigation of aircraft aeroelastic phenomena. The flutter computation in the frequency domain, using simple unsteady aerodynamic models and specialized software is nowadays an aerospace standard. The selected normal modes, control surface modes and rigid body modes should be here taken into account during design. The mechanical properties of structure are represented by modal parameters as mode shape, generalized mass, normal frequency and damping coefficient. For selected configuration of structure they can be determined only once, by computation or ground vibration test. Similar approach can be used for more detailed simulations in the time domain, in which a more credible unsteady aerodynamic models can be applied. Due to this approach, the "structural" part of problem is very simple. The resulting database (structural modes) is small and unvarying, so the whole time-domain computation can be provided only in a flow computation system, without data exchange between structure's and flow computation systems.