Mechanical properties of GRP composites with localised thermal damage

The effect of thermal damage on the mechanical properties of glass-reinforced polyester (GRP) composites is, investigated, GRP panels underwent surface heating to high temperatures (750 800 C) in a colic calorimeter to create localised regions of thermal damage having a circular, oval, square, diamond or irregular shape. The size of the heat-affected region ranged from 10% to 100% of the panel width. The heat damage consisted mostly of char from combustion of the polyester matrix and delamination cracks. After heating in the colic calorimeter. the GRP was cooled to room temperature and then the residual tension and compression properties were determined. Increasing the size and depth or the lire damage zone caused reductions to the stiffness and strength of the GRP. It was round that the shape of the heat-damaged region did not affect the mechanical properties. A model is presented for accurately determining the tension and compression properties or composites With localised heat damage of any shape.