The research is aimed to investigate the influence of spherical nanoparticles on the fracture
behavior of glass fiber/epoxy composites. Two different contents of silica nanoparticles, 10wt% and
20wt %, were introduced into the composite samples. Through a sol-gel technique, the silica particles
with diameter of 25 nm were dispersed uniformly into the epoxy matrix. Subsequently, the silica
epoxy mixtures were impregnated into the unidirectional glass fiber mat by means of a vacuum hand
lay-up process to form the unidirectional glass fiber/epoxy laminate. During the fabrication, a porous
film was inserted into the mid-plane of the laminate to generate the pre-crack. The Mode I fracture
toughness of the composites with different nanoparticles contents were then determined form the
double cantilever beam (DCB) specimens. Based on the experimental observations, it was found that
the glass fiber/epoxy composites with silica nanoparticles exhibit superior fracture toughness than
those that do not contain any silica particles. Scan Electronic Microscopy (SEM) observations on the
failure surfaces indicated that the enhanced fracture toughness could be due to the improved
interfacial bounding in conjunction with the nanoparticle debonding from the surrounding epoxy. In
general, such failure mechanisms may complicate the fracture process, dissipating more fracture
energy.
Effect of Testing Method Type and Specimen Size on Mode I Fracture Toughness of Kimachi Sandstone