The project supports development of the processing of composite materials using microwaves (MW) with the aim of making the process more attractive for fast(-er), low(-er) cost processing of (composite) materials. This is to be accomplished by further increasing the understanding of the effect of MWs in composite materials through the use of advanced characterisation techniques and numerical modelling.
When carbon fibre reinforced polymer (CFRP) composites are exposed to MWs, most of the energy is absorbed by the carbon fibres. This heating mechanism is different to the conventional heating mechanism where the heat is transferred from the surface through the thickness by conduction. This difference in heating mechanism/sequence will have an effect on the matrix, but also (and possibly more importantly) on the interface/interphase between the fibre and the matrix. Although significant work in the processing of composites using MWs have been reported in the past, there is a lack of understanding when it comes to the effect MWs have on the interface/interphase region. Standard test techniques, such as tension, shear and flexure provide some information regarding the mechanical performance of the material, however the results obtained will be based on the overall performance, rather than specific to ‘MW-affected’ regions/parameters.
Three specific areas will be investigated:
- Establishment of MW penetration depth test procedure;
- Evaluation of physico-mechanical performance;
Relevant Industry Sectors
Over the past two years, TWI has received enquiries and requests regarding MW technology have increased considerably. This is possibly attributed to the difficulties many companies are already facing in terms of improved material processing efficiency. Questions have been asked regarding the effects MWs have on the material. Companies are also keen to investigate properties such as fracture toughness, interfacial shear strength, environmental ageing, etc of MW processed composites rather than the ‘end application’. It is believed this comes from the ‘scepticism’ that still exists with MW technology for processing composites, as well as the lack of knowledge/understanding that currently exists for such technology – which is an obstacle when it comes to design and production of parts.