Study of thermomechanical coupling in carbon fibers woven‐ply reinforced thermoplastic laminates: Tensile behavior under radiant heat flux

The present work focuses on the thermomechanical behavior of carbon fibers woven‐ply polyphenylene sulfide (PPS thermoplastic)‐based composite materials subjected to the combined action of a tensile mechanical loading and one‐side heat flux (40‐60 kW/m2) representative of fire exposure. An experimental bench was specifically designed to provide an insight in the coupling between a medium heat flux thermal aggression and a tensile mechanical loading (either in monotonic or creep mode) within quasi‐isotropic C/PPS laminates. When subjected to a monotonic tensile loading, a 50% increase in the heat flux lead to a 50% increase of the temperature at the exposed surface resulting in a 10% decrease in the maximum load borne by the laminates. When subjected to a creep loading at 60 kW/m2 (worst case scenario with the cone calorimeter), by dividing by 2.6 the applied creep stress (from 31% to 12% of the ultimate strength σ0u), it results in a time‐to‐failure multiplied by 2.5. The temperature distribution on the exposed and back surfaces are measured to evaluate the influence of PPS matrix melting, pyrolysis, and fibers oxidation on the stress redistribution within the laminates plies. An experimental bench was specifically designed for simultaneously combining the action of a tensile mechanical loading and a one‐side heat flux provided by an electrical radiant heat source (representative of fire conditions). Using this specific device, the present study was aimed at evaluating the fire performance of carbon/polyphenylene sulfide (C/PPS) laminates through the investigation of weak coupling between thermal and mechanical behaviors in quasi‐isotropic carbon fibers reinforced PPS laminates.