Simulations of microwave propagation in delaminated unidirectional glass–epoxy laminate

Generally, delamination may lead to failures of composites structures directly or indirectly. Microwave techniques can be effective in detecting delamination within composites structures with relatively low electrical conductivity. The understanding of microwave propagation in delaminated composite materials is therefore important. This paper reports on the reflection and transmission characteristics of microwaves propagation at different frequencies within a unidirectional glass–fibre reinforced epoxy composite laminate. With the simulation, the presence/location/severity of delamination is linked to the variations in microwave reflection/transmission coefficients when compared to that of a signal without delamination influence. It has been found that reflection coefficient is more sensitive to the presence of delamination in comparison to the transmission coefficient for the far-field approach. In addition, scanning at frequencies within zero-crossing and reflection-lines intersection zones should be avoided as the ‘usefulness’ of the data is low.