28 April 2015
28 April 2015
IMDEA Materials and Fokker Aerostructures are collaborating to develop a novel multiscale simulation strategy to predict the mechanical behaviour of aeronautical composite laminates structures under static and low-velocity impact loads.
IMDEA explains that, the bilateral project VIRTEST, will lead to an improved understanding of the material behaviour and the guarantee of the correct modelling approach at different building blocks. The increased predictive capabilities will lead to a more efficient selection of physical tests, thus shortening the development times at Fokker.
According to IMDEA, fibre-reinforced polymers are nowadays extensively used in applications where outstanding mechanical properties are necessary in combination with weight savings. It says that good examples can be found in the B787 and A350, the last civil aircraft from Boeing and Airbus, respectively, containing up to 50% in weight of composite materials. However, despite all existing information and current knowledge about these materials, the accurate prediction of the failure stress of composite materials and structures has been an elusive problem because of the complexity of their failure micromechanisms. Due to this lack of knowledge on the mechanical behaviour of these materials, the traditional way to tackle the problem is through extensive and costly experimental campaigns which involve material characterisation through different levels of details, from small coupons to panels, subcomponents up to the final global structure.
IMDEA says the base of the traditional testing pyramid is the ply coupon level, involving a tremendous effort to test materials under tension, compression, shear, different directions, interlaminar toughness, etc, in order to fully certify the different ply properties. Moreover, additional tests should be performed under environmental conditions, different ageing conditions, fluids, etc which significantly delay the experimental campaigns in months and years for a fully material certification. The aim of VIRTEST is to increase the understanding of failure mechanisms in composites at each material scale by means of high-fidelity simulation hence reducing the need for physical testing. By identifying the relevant parameters affecting failure, this strategy can also be used as a design tool.
To this end, it explains that a coupled experimental-computational framework will be implemented at Fokker. The test pyramid will be extended at the base by including additional characterisation at the material constituent level, and micromechanical models will be implemented to obtain ply properties as input for the next building block, when extensive experimental ply characterisation is not yet available. A mesomechanics approach that accurately describes the different ply and interface damage modes, and their interaction, will be implemented to compute laminate response.