Hierarchically Organized Nano-modified Carbon Fiber Composites for Enhanced Fatigue Life of Structural Components

Abstract

Carbon fiber reinforced polymer composites (CFRP) are ubiquitous in engineering applications where they are employed as structural components. Fatigue failure which originates in matrix of CFRP is a major design constraint in these composites. In this work we demonstrate considerable increase in fatigue life in nano modified carbon fiber reinforced polymer composite (nanoCFRP) through addition of nanoscale silica particles. Fumed silica particles are used as nanofillers which are incorporated in epoxy initially to explore their effect on fracture and fatigue performance. The results indicate improvement uniform improvement in the fatigue life with increasing silica loading fraction. Fractographic analysis performed indicated presence of various toughening mechanisms like crack deflection, void growth and heterogeneity induced toughening. The epoxy-silica nanocomposite was then used as the matrix material with carbon fibers to fabricate nanoCFRP with different silica loading fractions. nanoCFRP samples were initially tested statically in three point bending setup and the static strength was found to be uncorrelated with the loading fraction. The cyclic flexural tests, however, revealed significant improvement in fatigue life in nanoCFRP composites. The fatigue life improvement was pronounced in high cycle fatigue regime.