A validated finite element framework to realise the potential of thermoelastic stress analysis for quantitative studies of laminated CFRP structures

Quantitative Thermoelastic Stress Analysis (TSA) of laminated carbon fibre reinforced polymer (CFRP) structures poses a significant challenge, as the stress induced temperature change, caused by the thermoelastic effect, is influenced by heat transfer. Both in-plane and through the thickness heat conduction occurs, which is mainly driven by the step changes in the stresses at the ply interfaces in a multidirectional laminate. In most materials cyclic loading at sufficiently high frequencies minimises heat transfer. However, because of the large degree of anisotropy in both the thermal and mechanical properties of CFRP, adiabatic conditions do not occur at achievable loading frequencies. To understand the thermomechanical coupling in CFRP, a comprehensive experimental evaluation of an existing meso-scale finite element (FE) model that is able to reproduce the thermoelastic heat source ply-by-ply, is presented. Hence, a validated modelling framework is created that enables quantitative TSA to be carried out on CFRP structural components. It is established that the model is able to accurately predict the effects of different loading frequencies, layups, resin-rich regions and the effect of the necessary matt black paint surface layer. The modelling approach is demonstrated through a challenging experimental validation followed by application on a typical quasi-isotropic laminate. A practical application is presented, where a CFRP component with unknown material properties is assessed to demonstrate the utility of the modelling framework.