Materials and process
Research activities within this research focus include biocomposite compounding, extrusion of short-fibre composites, reactive processing of thermoplastic composites, metal composites hybrid laminates, and thermoset composite assembly.
Composite Assembly Process
Thermoset Composite Welding (TCW)
UQ Composites was involved in the development of a new technology, which allows the rapid joining of epoxy composite components for applications in commercial aircraft’s primary structures. The process involves the incorporation of a thin thermoplastic film prior to curing of the composite, enabling the subsequent welding of additional components via a common thermoplastic layer. UQ Composites’ work focused on understanding the complex interfacial mechanisms occurring at a molecular level between the dissimilar materials and developing a simulation tools for predicting the melt flow during the secondary welding stage. The technology is patented by the Cooperative Research Centre for Advanced Composite Structures (CRC-ACS) and was developed in collaboration with Airbus in Toulouse.
Adhesive Bonding of Composites
Damage detection in composite joints assembled through adhesive bonding can be challenging as laminar damage may not be visible. Non-visible damage can be in the form of internal delamination or in some instances due to disbonding or weakly bonded interface (also referred as ‘kissing bonds’). These damages are currently below the detection limit of conventional non-destructive techniques and cannot be detected. The UQ Composites Group is conducting research on being able to reproduce these ‘kissing bonds’ on a laboratory scale and on the use of non-linear ultrasonic techniques to overcome these issues. In the presence of non-linearity the interaction of ultrasonic and vibrational waves give rise to new frequency components, which can provide information on the laminar damage of composite parts.
Composites Manufacturing and Processing
Short-fibre composite extrusion
Exrtrude and injection moulded fibre reinforced plastics are increasingly replacing metals. There is an ever increasing choice of different fibres and resin systems allowing a near infinite amount of different combinations and also allowing tailoring to a specific application. UQ composites has experience in the compounding (mixing of fibres, matrix and additives), material selection, additvation as well as the characterisation of the resulting materials. We have developed analysis techniques to determine fibre volume fraction and distribution and have access to equipment that can determine chemical composition or surface characteristics.
Reactive processing
Thermoplastic composites offer a series of advantages over thermoset composites. Currently the potential of thermoplastic composites is not fully utilised due to complex and costly manufacturing processes. Reactive processing is emerging as a novel processing technique which allows processing of thermoplastic resins at viscosities comparable to those of thermoset resins. This opens up new manufacturing methods previously reserved to thermoset resins and will allow the cost-effective production of complex parts.
High pressure Resin Transfer Moulding (RTM)
How nice would it be if thermoplastic resin can be processed in the same way as a thermosetting resin? This is exactly what reactive processing can achieve. Through in-situ polymerisation resin can be processed at a ‘water like’ viscosity allowing the use of standard Thermoset resin processes such as resin infusion or RTM. This novel process will cobine the manufactuign advantages of thermoset processes with the advatagous material properties of therompalsic resins. UQ composites is in the process of commissioning a unique piece of equipment that allowes reactive processing at temperatures as high as 260 C and is capable of metering up to four components individually.
Hybrid Structures
Metal composites hybrid laminates
Fibre metal laminates (FML) are increasingly finding use in light weight applications by combining benefits of both composite and metal components such as fracture toughness and impact resistance. They have the potential to replace traditionally used monolithic metal or composite structures in special applications.
Our research is focusing on developing manufacturing processes, characterising their mechanical and environmental behaviour and simulating damage initiation and propagation.
Thermoset/thermoplastic hybrid composites
The combination of thermoplastic materials with thermoset resins is being increasingly used in advanced applications of composite materials. Common materials for aerospace applications include the use of polyetherimide (PEI), polyether sulfone (PES), polysulfone (PSU) or polyamides (PA6 or PA12) in combination with epoxy resin. Whether the thermoplastic material is in the form of a toughening particle, a continuous fibre, or a surfacing film, the interface formed between these two materials is very complex and is often found to dictate the overall performance of the composite. The UQ Composite Group has developed extensive knowledge on the different mechanisms such as adhesion, interdiffusion, and chemical bonding, occurring at these interfaces. This also includes effective techniques for characterising the interfaces on a sub-micron level, and methods of assessing their mechanical performance.
Biocomposites
Biocomposite compounding and extrusion
Biocomposite materials are rapidly emerging as a more sustainable alternative to traditional engineering materials. Twin-screw compounding followed by extrusion or injection moulding is one of the most promissing and cost effective process routes. The team has experiacnce with compounding a large variety of plastics (bio and syntethic) as well as with the compounding of different natueal fibres and powders.
Bioresins
UQ is a key partner in the international BIOSPHERE project with Airbus research centre AMIC, Universiti Putra Malaysia and adhesive manufacturter MAC. UQ is leading the FST testing part of the project.
Success stories
Rapid assembly of commercial aircrafts
UQ Composites has contributed to the development of a new technology, to allow the rapid joining of commercial aircraft’s primary structure composite components. The technology known as Thermoset Composite Welding (TCW) was patented by the Cooperative Research Centre for Advanced Composite Structures (CRC-ACS) and developed in collaboration with Airbus in Toulouse. UQ Composites’ involvement to this project extended over a period of five years through a post-doctoral position and two PhD projects. The work focused on gaining a fundamental understanding of the assembled interface, and the contribution made by our group was key to the refinement of such an innovative technology and to its future implementation.