Fracture toughness (Mode I) characterization of SiO2 nanoparticle filled basalt/epoxy filament wound composite ring with split-disk test method

Matrix cracking which is the major initial form of damage in fiber reinforced polymer composites plays significant role in determining the fracture toughness. The fast crack propagation in polymer matrix causes to decrease the fracture toughness of fiber reinforced polymer (FRP) composite. In order to retard the fast crack propagation in polymer matrix and provide to increase of the fracture toughness of FRP composite, the polymer matrix of FRP composite is modified by filling the different kinds of nanoparticles. In such a way, the crack propagation leads to retard and dissipate the stress concentration affected to form the fiber cracks along of fibers in composite structure. In this study, basalt fiber was used as reinforcement material in ±[55]6 filament wound ring composite for creating the alternative to carbon, kevlar and glass fibers, to contribute to the research studies and literature. SiO2 nanoparticles that provides to form the effects of fracture toughness mechanism based on the effect of retarding crack propagation were filled into epoxy matrix to increase the mechanical properties and fracture toughness of ±[55]6 filament wound BFR/Epoxy ring composite. The split-disk tensile tests of single edge notched and un-notched ±[55]6 filament wound BFR/Epoxy ring composite specimens were conducted to determine the mechanical properties and mode I fracture toughness. SiO2 nanoparticle addition into epoxy matrix of ±[55]6 filament wound BFR/Epoxy ring composites has given the results of hoop tensile stress within the range of 27.7-30.3%. The fracture toughness of composite ring specimen was specified by ASTM E 399-12E3 by adapting to the directed mode I crack propagation and compared with each other. An effective increase in mode I fracture toughness of 43%-50% was obtained at 4 wt% addition level of SiO2 nanoparticles. The crack branching in epoxy matrix provided by SiO2 nanoparticle, matrix cracking, debonding, delamination and fiber breakage failures has been observed via microscope and SEM analysis.