Influence Of Polymer Coating Thickness On Damage Tolerance And Residual Strength Of Composite Material

Abstract The low impact resistance of laminated polymer composites is a significant problem. Even barely visible impact damages can significantly decrease the residual strength of the composite. In this article, the effect of the thickness of a polymer coating based on hollow glass microspheres on the damage tolerance and residual strength of glass fibre-reinforced plastic (GFRP) was studied. 4 mm thick GFRP specimens with polymer coatings of different thicknesses were prepared. The thickness of the coatings varied from 0.4 mm to 1.2 mm. The specimens were tested on a vertical drop tower system with impact energies up to 25 J. The dimensions of the obtained defects were determined using infrared thermography. The residual strength of the specimens was determined using the Flexure-After-Impact protocol. It was found that the 1 mm thick coating with a surface density of 650 g/m2 made it possible to reduce the damaged area by 35% and to increase the residual flexural strength of the GFRP specimens by 27% in comparison with the uncoated ones.