The effect of additives on the low velocity impact properties of low density fiber sandwich panels

Sandwich structures with carbon fiber-epoxy face sheets and polyvinyl chloride foam core material are known for their high strength and flexural stiffness despite their low weight. However, poor impact characteristics make it difficult to operate these materials under impact load without failure. In this thesis work, it is aimed to increase the impact resistance of low weight composite sandwich structures. The focus is on the epoxy matrix, which has a brittle structure, because the improvement in impact properties is intended to be achieved without significant weight gain. Graphene, boron carbide and kaolin were used as additives in this study for the application of matrix toughening method. 2%, 5% and 10% by weight additives were mixed into epoxy matrix and sandwich structures were produced by hand lay-up and vacuum bagging method. All configurations were subjected to a low velocity drop weight impact test at three different energy levels (10 J, 17.5 J and 25 J). The results obtained from the experiments and the images of the post-impact damage of the sandwich structures are presented comparatively. According to the test results, configurations containing boron carbide additive were the most resistant to impact load. It has been observed that graphene additive increases impact resistance at low additive ratios, while kaolin additive has no significant effect on impact resistance.