Impact Resistance of Woven Fiber Reinforced Polymer Composites

Background: The performance of fiber reinforced polymer (FRP) composite materials is usually characterized by damage resistance of the laminates. Damage resistance of a composite material is commonly defined as a resistance to impact damage. Impact by foreign objects is expected to occur during manufacturing, service and maintenance operation. In composite structures, impact loads create internal damage that often difficult to be detected by visual inspection. This internal damage can cause severe reductions in strength and can grow under continuous loading. In this study, the impact resistance behavior of Kevlar fiber reinforced polymer (KFRP) and glass fibers reinforced polymer (GFRP) were studied experimentally using drop weight impact test according to ASTM D7136. Impact resistance behavior was studied at nominal impact energy level of 47 J. The influence of alumina powder Al2O3 (size 63µm) on impact properties of GFRP and KFRP was also investigated. Objectives: The purposes of this study are to evaluate the impact resistance behavior of KFRP and GFRP as well as to investigate the effect of micron size alumina filler on the impact properties of both composite laminates. Results: The unmodified specimens of KFRP and GFRP were fabricated using two techniques namely hand lay-up and vacuum bagging. In addition, specimens of 3 wt% alumina filled KFRP and GFRP composites were fabricated by using vacuum bagging method. In order to investigate the effect of fabrication method and influence of alumina filler on impact properties, drop weight tests were performed to measure the impact resistance of the specimens. From the results, it was observed that the impact resistance of specimen fabricated using vacuum bagging method was better when compared to that of specimens fabricated using hand lay-up method. Additionally, the presence of alumina fillers enhanced the impact energy absorption of FRP composite. Conclusion: Fabrication method plays important role in enhancing the properties of FRP. Based on the results, the incorporation of micron size alumina filler enhanced the energy absorbed during crushing, increased stiffness and strength of composites hence improved the impact resistance.