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/m(2)) 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/m(2) (worst case scenario with the cone calorimeter), by dividing by 2.6 the applied creep stress (from 31% to 12% of the ultimate strength sigma 0u), 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.