Multiscale investigation of the viscoelastic contribution to the mechanisms governing self-heating in unidirectional laminated composites

Understanding the mechanisms responsible for self-heating in laminated composites under cyclic loading is a critical step toward establishing a robust link between the dissipation estimated via thermal measurements and fatigue behaviour. In the literature, premature connections are sometimes made between temperature rise and fatigue lifetime without sufficient verifying the underlying physical mechanisms. The present article proposes an approach based on combined mechanical and thermal models to rigorously assess and validate this relationship. In this study, a multiscale modeling approach is used to clarify the role of the matrix’s mechanical behaviour in the energy dissipation of unidirectional plies. The non-linear viscoelastic behaviour of the resin is characterized through dedicated mechanical tests. Homogenization procedures are then used to derive the mesoscopic response of individual plies, which in turn allows the overall behaviour of the laminate to be assessed. Applying this framework to a quasi-isotropic laminate subjected to tension-tension cyclic loading reveals that the majority of the dissipation originates from the ± 45 ° plies, as expected. The proposed multiscale approach does not introduce any dissipation due to damage. Nevertheless, the predicted dissipation based only on the viscoelastic behaviour of the resin remains in good agreement with the experimentally observed dissipation of a quasi-isotropic laminate. This may indicate a limited contribution of these damage mechanisms. The next step is to propose a scenario explaining how the dissipation observed in a particular ply may serve as a reliable indicator of fatigue failure.