Project HieroComp

This project aims to develop, characterize and technologically implement of a new class of composite materials: functional, hierarchical composites for structural applications. These materials will have microstructure engineered on multiple scales and will provide enhanced modulus, strength and toughness compared to the equivalent materials in use today. In addition, they will be engineered such that the state of damage will be monitored while in service (structural health monitoring). This feature classifies them as functional materials.

The starting point will be standard epoxy-based glass fibre composites which are used today in many applications including automotive and aerospace. The novelty of the proposed work stems from the following innovations: A) The matrix will be modified using nanoscale fillers (silica nanoparticles) whose functionalisation allows control of the strength of their interface with the matrix. The strength of the interface will be controlled by exposure to UV light or to X-Rays and will be tuneable after the composite is produced. This technique will also allow inducing spatial patterns in the distribution of fillers with strong and weak interfaces by exposure of the sample to interference patterns of the respective curing radiation. The fillers with weak interfaces are expected to increase the toughness, while those with strong interfaces will compensate for the potential strength and modulus reduction associated with the presence of weak interfaces. The capability offers new ways to engineer the microstructure of the material for optimal system scale properties. B) The interface of glass fibres and matrix will be functionalized and similarly controlled by exposure to curing radiation. An epoxy-based “interphase” located between fibres and matrix will be developed by controlled curing of pure and filled epoxy layers deposited on fibres before pre-preg formation. C) A percolated network of conductive fillers (graphene) will be developed and will be used to monitor damage accumulation while the material is in service.

The most promising nanoscale engineering methods of the type described above will be used by the industrial partners to develop products with enhanced properties. Modelling will be performed to determine the values of system parameters leading to maximum composite toughness and strength. Only parameters accessible experimentally will be considered. Extensive characterization will be performed at all relevant scales to test material characteristics and trends.

The integration in production will be performed at the prototype level in specific applications: composites with fibres for wind turbine towers (Compozite-Romania), automotive applications (Benteler-SGL, Austria) and advanced epoxies for special applications (bto-Epoxy-Austria).

The work will have impact beyond the output of the participating companies, as these materials are of interest for multiple industries. In particular the capability to monitor the state of damage is critical in many sensitive applications.

To reach these objectives, we have assembled a team of researchers from academia and industry, from two countries -Austria and Romania- having complementary expertise. The group from Montanuniversität Leoben specializes in filler functionalisation and composite characterisation, while the Romanian group bring expertise in composite processing and multiscale modelling. The industrial partners produce advanced epoxies (bto-Epoxy-Austria) and commercialize structural components from epoxy-fibre composites (Compozite-Romania, Benteler-SGL-Austria). The project will also promote European integration both at the academic and industrial levels and will promote the development of human resources.

The societal benefits of the project results are related to the applications of epoxy composite and are associated with enhanced safety and reduced weight of structures made from such composites with longer fatigue life and higher strength.