A study of the thermomechanical behaviour of CFRP laminate using small-scale apparatus

Abstract

An approach for quantifying the thermomechanical bending behaviour of a CFRP laminate has been developed. The proposed test method allows the coupled thermomechanical behaviour, relating the mechanical performance degradation with the temperature gradient and hence the gradient in mechanical properties inside a composite material to be investigated. Furthermore, the data can extend its applicability to constitutive modelling of composite material under fire conditions and provide experimental results essential for numerical model verification. Drawing on material flammability, the thermal load is induced using radiant heat flux, which allows a systematic evaluation of the material response. By manipulating the applied heat flux, the process causing failure is shown to vary. At low heat fluxes, the failure is dominated by a large proportion of the specimen reaching the glass transition temperature. At higher heat fluxes, the failure is dominated by pyrolysis and oxidation of the CFRP at the locally exposed surface, resulting in a more brittle failure. Because the developed apparatus allows the systematic variation of the thermal and mechanical load, it is possible to utilise it to replace conventional uncoupled approaches where residual mechanical properties are often used to assess the performance of materials exposed to thermal loads.