Simulation of carbon fibre composites in an industrial microwave

The ability of microwave radiation to penetrate and interact directly with materials has led to its extensive use in food and drug industries, and more recently in composites manufacturing. Microwave heating of composites allows rapid heat transfer throughout the material thickness with reduced thermal gradients and processing times as well as energy efficiency. Design of microwave systems to process composite parts with various geometries and sizes demands improved understanding of electromagnetic energy distribution and factors influencing it. Finite-element (FE) models can be efficient design tools in such cases, as physical experimentation can be impractical. In this study, a fully-coupled FE model of a carbon fibre composite in an industrial microwave environment is developed using COMSOL Multiphysics®. The effects of the heating process parameters including the number of active magnetrons, specimen thickness and the variation in the frequency of radiation on the electromagnetic field distribution are studied. The FE model showed that a substantial difference in the electromagnetic field distribution exists for the frequencies above 1 GHz compared to the lower frequencies in the microwave regime, resulting in non-uniform heating

The Effects of Absorbing Materials on the Homogeneity of Composite Heating by Microwave Radiation

When cured in a microwave, flat thin composite panels can experience even heat distribution throughout the laminate. However, as load and geometric complexity increase, the electromagnetic field and resulting heat distribution is altered, making it difficult to cure the composite homogeneously. Materials that absorb and/or reflect incident electromagnetic radiation have the potential to influence how the field behaves, and therefore to tailor and improve the uniformity of heat distribution. In this study, an absorber was applied to a composite with non-uniform geometry to increase heating in the location which had previously been the coldest position, transforming it into the hottest. Although this result overshot the desired outcome of temperature uniformity, it shows the potential of absorbing materials to radically change the temperature distribution, demonstrating that with better regulation of the absorbing effect, a uniform temperature distribution is possible even in non-uniform composite geometries

Interfacial optimisation of glass fibre reinforced composites by plasma polymerisation

EThOS - Electronic Theses Online ServiceGBUnited Kingdo