During their service life, aerospace structures can be subjected to a variety of dynamic loading cases. Crash/impact is one of the most concerning cases due to its possible disastrous consequences. Impacts on aerospace structures can be produced by the accidental or deliberate hit of an object into aircraft. Hailstones, bird strikes, runaway debris, tyre fragments or even other fragments from the aircraft structure that could be ejected in case of an accident (i.e. uncontained rotor engine failure) are the main examples produced in the aerospace sector. Therefore, it is crucial to understand how the materials used in the aerospace sector behaves under dynamic loadings.
Composite materials may exhibit strain rate effects, therefore robust and industrial dedicated dynamic coupon and element level tests, analysis and modelling methods are then necessary to design and certify composite airframe structures. The analysis tools based on static formulations could be far away from the actual material and structural response, and hence a dedicated methodology is needed for dynamic loading states. This is what the proposed BEDYN project will deal with.
The aim of BEDYN project is to address a methodology to properly characterize the dynamic behaviour up to rupture of thermoset polymer-based composite structures submitted to dynamic loading. Different main objectives can be defined:
Ob. 1) Define a modelling approach for dynamic loading events, suited to industrial needs for emergency situations applications.
Ob. 2) Define dynamic tests, which include the definition of: specimens, test setups, and data reduction methods. Three different specimen levels are set: “coupon”, for characterizing basic properties of the composite material (ply), interlaminar (delamination) and adhesive interfaces; “element”, they include what can be understood as small size demonstrator (under this category the response of the flexural, notch effects and bearing will be analysed); “structure”, they are devoted for characterizing the behaviour at a subcomponent level under out-of-plane dynamic loads. In order to describe properly the possible dynamic effect in some material/structure behaviours, a quasi-static test campaign is also considered for any of the specimen levels accounted for.
Ob. 3) Define a calibration and validation process of the models.
Ob. 4) Demonstrate and evaluate the proposed methodology based on tests performed.
As the BEDYN project has achieved the defined objectives, it can be concluded that BEDYN has contributed to the consolidation of the use of numerical simulation in the design phase of polymer-based composite structures under dynamic loading. The BEDYN project has addressed innovative technologies that allow better product development thanks to a better knowledge of the behaviour of composite materials under dynamic loading. The maturing and validation of technologies is a key aspect of integrating research into the development process of industrial activities and next generation aircraft.
