Characterisation of composite hybrid marine grade sandwich panels

Abstract

Hybrid sandwich panels are designed according to BS12215-5:2008 for marine craft, fabricated using wet layup and cured under a vacuum pressure process. Skins use marine grade orthophthalic polyester, POLYLITE® 440-M850, resin and CSM/woven E-glass; the core is DIVINYCELL® H100 closed cell linear PVC foam. Single skin laminates have improved properties, 40% thickness, 70% fibre weight of traditional laminates. The flexible skins are combined with the light weight core simultaneously during fabrication, designed to support bottom & side pressure in the displacement and planning modes, they are able to sustain the slamming & pounding commonly encountered by such craft. The panels predict further reduced skin thickness; core thickness varying according to the panel size and location; employing larger panels implies a reduction/elimination of the wooden stiffeners commonly present in single skin FRP hull structures. Characterisation of the panels follows ASTM D7249M–06, D7250–12 & C393M–06. Comparison of experimental data with the theoretical modified to reflect the composite skin material responses and the fabrication process is undertaken. The resulting panel offers additional safety of the marine craft having a double hull configuration utilising the top and bottom skins, with an energy absorption core medium. It is proposed that this double hull configuration is adopted as a safety aspect and standard method of fabrication, against accidental sea grounding or impact.