Kerosene flame behaviour of C/PEKK composite laminates: Influence of exposure time and laminates lay-up on residual mechanical properties

This work examines the influence of a kerosene flame on residual mechanical tensile properties composite laminates manufactured by thermo-consolidation process from unidirectional (UD) carbon fibers and Polyether Ketone (PEKK) thermoplastic. Considering with two stacking sequences (orthotropic or quasi-isotropic - QI), exposure (116 kW/m2 1100 °C) composites structural integrity was examined as function time (5-10-15min). The discussions fire- mechanically-induced damage mechanisms are supported fractographic analysis specimens. Not surprisingly, longer exposures to lead gradually increasing damages within at different scales (micro-meso-macro), ultimately resulting in degrading bearing capabilities material. With respect virgin specimens, axial strength decreases almost 60 40% (after 15min exposure) orthotropic QI laminates, respectively. At same time, stiffness is about 30 20% lower exposure). Contrary well-defined areas observed through thickness laminates: severely degraded one virtually undamaged one. first corresponding exposed surface side significantly damaged (fibers oxidation pyrolysis PEKK matrix leading an extensive delamination). second back-surface characterized plies very little damage. When loaded tension, “undamaged” breakage 0° fibers. failure mechanism shows that these capable bear significant portions loading contrary specimens which delamination prevails whole thickness.