Meso-structure-based thermomechanical modelling of thermoplastic-based laminates subjected to combined mechanical loading and severe thermal gradients

This paper presents a numerical modelling methodology to investigate the thermo-mechanics of carbon reinforced thermoplastic-based laminates in the situation of mechanical loading combined to thermal gradients. It concerns in particular the case of thermal irradiation on one face of the laminate, where temperature varies both from point to point of the laminate and through time, and ranges from the ambient to the temperature of matrix decomposition onset. Temperature is the key variable to determine the physical state and the properties of each phase of the composite. Particular attention is therefore paid to identifying the respective material properties according to temperature. The developed numerical model is based on an explicit representation of the yarn-matrix spatial arrangement within a representative volume element of the considered laminate. From this model the influence of the heterogeneous matrix thermal degradation on the macro-scale thermal dependent properties of the composite is discussed. Such a modelling requires the consideration of a wide range of phenomena (modification of physical and mechanical properties) and a comprehensive set of thermal boundary conditions (heterogeneous distribution of heat flux density on the sample surface, convection, radiation). The proposed model provides a very good prediction of the laminate’s stiffness evolution according to temperature up to the onset of thermal decomposition temperature. It further enables to analyze the gradual efforts take up between the plies when a constant mechanical loading is combined to a heat exposure.