Aeroelasticity is the branch of physics and engineering studying the interactions between the inertial, elastic, and aerodynamic forces occurring while an elastic body is exposed to a fluid flow. The study of aeroelasticity may be broadly classified into two fields: static aeroelasticity dealing with the static or steady state response of an elastic body to a fluid flow, and dynamic aeroelasticity dealing with the body's dynamic (typically vibrational) response.
Aircraft are prone to aeroelastic effects because they need to be lightweight while enduring large aerodynamic loads. Aircraft are designed to avoid the following aeroelastic problems:
- divergence where the aerodynamic forces increase the twist of a wing which further increases forces;
- control reversal where control activation produces an opposite aerodynamic moment that reduces, or in extreme cases reverses, the control effectiveness; and
- flutter which is uncontained vibration that can lead to the destruction of an aircraft.
Aeroelasticity problems can be prevented by adjusting the mass, stiffness or aerodynamics of structures which can be determined and verified through the use of calculations, ground vibration tests and flight flutter trials. Flutter of control surfaces is usually eliminated by the careful placement of mass balances.
The synthesis of aeroelasticity with thermodynamics is known as aerothermoelasticity, and its synthesis with control theory is known as aeroservoelasticity.