Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - DYNACOMP (Dynamic behaviour of composite materials for next generation aeroengines)

Teaser

DYNACOMP’s main technological contribution aims at providing means of using lighter composite materials in turbo-engines. For instance, composite materials would allow increasing the size of the fans and thus the efficiency of turbo engines, and this possibility is already...

Summary

DYNACOMP’s main technological contribution aims at providing means of using lighter composite materials in turbo-engines. For instance, composite materials would allow increasing the size of the fans and thus the efficiency of turbo engines, and this possibility is already under study. However, although the in-plane properties of composites laminates, as the stiffness and strength, are superior to metals, one of the biggest hurdles is the extreme sensitivity to out-of-plane and dynamic loading events. This later scenario is crucial in fan blade applications where foreign object impacts (birds, ice, debris, etc.) could constraint the final application. The use of a new generation of carbon fabrics and more specifically, new polymer resins, is therefore required to push composite materials towards their maximum performance limits in this application, but the existing fundamental knowledge on the high strain-rate behaviour of composite materials is still limited. For this reason, the traditional way to introduce new composite materials has been through extensive and costly experimental campaigns based on a trial and error approach. A new design paradigm is thus needed, to reduce cost and lead time in design.

DYNACOMP aims at closing this gap by the development of a consistent, physically based and multiscale simulation strategy for the analysis of the dynamic and impact behaviour of the next generation of composite materials to be used in fan blade manufacturing. The proposed simulation strategy describes systematically the material behaviour at different length scales from ply/tow to laminate and to component level accounting for strain rate effects. One additional advantage of this bottom-up multiscale approach is that changes in the properties of the constituents (fibre, matrices), the fibre architecture or laminate lay-up can be easily incorporated to provide new predictions of the macroscopic behaviour of the composite under impact. The new design paradigm is not new, as the last decade has seen the expansion of new advanced computational methods which involve physical and mechanical characterization combined with ‘virtual testing’ through different levels of detail, from small coupons to panels, subcomponents up to the final global structure. Nonlinear numerical analysis based on the Finite Element (FE) method have been employed with great success to increase confidence in the large-scale and expensive structural tests that are required before certification, as well as to understand in more detail the likelihood, causes and consequences of structural failure. Although this methodology has been very useful for the design of aircraft structures, it has not been extended for components working under impact conditions, which constitutes the main scientific challenge of DYNACOMP.

Work performed

For the establishment of the new design paradigm, DYNACOMP aims at pursuing some specific research objectives, in the framework of the two research projects accomplished by the two Early Stage Researchers (ESRs) of the network. In the following, the main progress achieved in the first half of the project is summarised with respect to each of these objetives:

• Objective 1: The development of novel experimental characterization techniques, non-existent nowadays, for the measurement of the constituent properties, fibre, matrix and fibre/matrix interface, by means of micromechanical tests at high strain rates: During the first half of the project, new instrumentation has been added to an existing nanoindentation platform that allows the direct measurement of the dynamic load during an indentation experiment under impact conditions. This breakthrough is important to allow the characterisation of the composite matrix under dynamic strain rates at the microscope.

• Objective 2: The development of novel experimental fracture testing techniques to characterise intralaminar and interlaminar damage in composite laminates under dynamic conditions. During the first half of the project, novel methodologies have been established to characterise the interlaminar and intralaminar fracture modes in composite laminates, based on new interlaminar shear strength tests and compact tension tests, respectively, carried out at large strain rates in a servo-hydraulic mechanical testing machine.

The novel tests developed are being applied to the three different composite laminates under study in the project.The results will serve as the basis for the development of the new design paradigm for the next generation of composite materials under dynamic loadings, using an experimentally informed, physically based and multiscale simulation strategy.

Final results

The main socio-economic impact of the DYNACOMP project is expected to be the establishment of a new design paradigm, based on a physically based and multiscale simulation strategies to reduce cost and lead time in the introduction of the next generation of composite materials in applications where the dynamic and impact behaviour is important, such as, for instance fan blade manufacturing. The use of composite materials in aircrafts has the potential of contributing towards reducing the environmental footprint of the aeronautical sector. New, eco-efficient aircrafts are challenged by a demand to significantly reduce the CO2 and NOx emissions, and one way to reduce environmental footprint is by the reduction of structural weight. As a result, Fibre-Reinforced Polymers (FRP) are nowadays extensively used in applications where outstanding mechanical properties are necessary in combination with weight savings. Good examples can be found in the A350 or the B787 Dreamliner, containing up to 50% in weight of composite materials used for wings, fuselage sections and tail surfaces. However, the use of composite materials in other parts of the aircraft, such as turbo engines, is still very limited, even though the increase in efficiency that could be potentially accomplished by the replacement of traditional metallic alloys by means of lighter composite materials is tremendous.

On top of the socio-economic and societal implications, the DYNACOMP project has set up the grounds for a European Industrial Doctorate (EID) program between IMDEA Materials Institute, the Polytechnic University of Madrid and Hexcel Composites Ltd. In the framework of this EID, early stage researchers are receiving a multidisciplinary and intersectorial training in the area of structural composite materials, including not only technical training, but also training on transferable skills, such as communication, innovation and management. The program has already organised a Summer School on the topic and will organize an industrial workshop at the end of the project to disseminate the outcomes.

Website & more info

More info: http://dynacomp-project.eu/.