The use of composite materials as principal structural elements in an aircraft requires the complete understanding of their mechanical properties. In particular, when structure is subjected to high frequency loading conditions (i.e. low and high energy impacts) phenomena such as wave propagation, strain rate dependences, delaminations and rupture need to be fully understood. This is crucial to obtain certification of aeronautical structures like those proposed within the “Clean Sky - Green Regional Aircraft” initiative.
Current numerical models are based on tests and technologies developed during the nineties in European R&T Programs. Since then, significant progress has been achieved in the development of physically-based models and multiscale modelling strategies, which provide more accurate results and can be applied to different materials. In the CRASHING project, the state-of-the-art in multiscale simulation of composites were transferred to the current numerical tools used by the industry in the simulation of the mechanical behaviour of composite structures for aerospace applications. The project was focused on composite materials currently used in aircraft innovative designs. In addition, new materials with potential application in the future were assessed with respect to the database generated along the project.
The objective of CRASHING project was to develop a multi-scale model approach that takes into account the physical mechanisms of damage at the different length scales so the influence of the microstructure and loading conditions can be taken into account rigorously. The multiscale approach described systematically the material behaviour at different length scales from ply, laminate to component levels. Final models of the multi-scale approach were suitable for simulations of aircraft crash-landing, ditching, bird strike, ice impacts and, in general, situations where the aircraft is subject to high frequency dynamic loads phenomena.
In the project CRASHING an enhanced analysis strategy for composite structures suitable for accurate simulations of high frequency dynamic load events was developed and implement in the Topic Manager (TM) engineering environment. Towards this end, the state-of-the-art in techniques of modelling and simulation of composite materials was transferred to the TM, and implemented in the current numerical tools used by the relevant industry sector in general in the simulation of the mechanical behaviour of composite structures for aerospace applications (i.e. ESI – PAMCRASH).
Overall, a multiscale analysis and simulation approach, rooted in solid material characterization experiments, to take into account the physical mechanisms of damage in composites at the different length scales from ply, laminate to component levels, was developed, implemented and validated using industry use cases. The approach was focused in composite materials currently used in aircraft innovative designs as well as new materials with potential application in the future.
Overall, in the CRASHING project five different composite materials were addressed at their three length scales. It was demonstrated that the implemented simulation approach for these materials and structures will be suitable for simulations of aircraft crash-landing, ditching, bird strike, ice impacts and, in general, situations where the aircraft is subject to high frequency dynamic loading phenomena.