Damage Caused To Aircraft By Object Impacts During Flight

The Department of Continuous Media and Structural Theory at the University Carlos III of Madrid (UC3M), in collaboration with the aeronautical companies EADS-CASA, EADS-SOCATA (France) and AERNNOVA, is executing several research projects involving the study of the behaviour of structural elements of planes that suffer an impact, a situation that planes might experience during their years of service. As a result of this collaboration, experimental devices for the analysis of aeronautical components and numerical models are being developed, providing verification of the behavioural hypothesis for aeronautical structures of planes.

The research, which started in the year 2004 and still continues today, analyses problems that need to be evaluated for the certification of aircrafts, such as the question of impacts of external bodies against the airplanes during landing and take-off, comparable to the case that caused the accident of the Concorde on 25th July 2000.

On that occasion, the impact of an object against the wing of the supersonic plane during take-off caused a fire in the engine that led to the death of over a hundred passengers as well as ruining the impeccable record of the famous aircraft.

The risk of impact can also come from meteorological conditions, such as impacts of lumps of ice originating either from hail storms or the loose ice that sometimes accumulates on the plane itself. Ramón Zaera, Director of the Continuous Media and Structural Theory Department at the UC3M, states that the objective is both to develop an experimental study that reproduces the operative conditions of the aeronautical components as well as to produce numerical models that simulate the application of impulsive loads on the structures, the effect of changes of temperature and the damage caused to the components.

Supersonic trials

The developments in this field, are related to great aeronautical engineering challenges in Europe, so it is the case of the enormous Airbus A380 and the future generation of the A320, which were tested in a pioneering mechanical impact lab in Europe that was created by the UC3M and EADS-CASA for the execution of complex experimental procedures. Their pneumatic launchers, consisting of tubes about 4 meters in length, permit the reproduction of impacts and collisions on structural elements of the fuselage, wings, stabilizers or the gondola of aircrafts with speeds ranging from 300 km/h to 3,000 km/h. This lab, located on the Leganés campus of the university, has been researching projects summing up to 900,000 Euros since the year 2004.

The impact process on aeronautical structures takes place in a very short period of time, in the range of a few milliseconds, which makes data acquisition harder in experimental tests and necessitates the consideration of inertial effects and non-linear behaviours when using mechanical models of materials. This is why it is necessary to use numerical simulations of the experiments using specific models.