ABSTRACT
M. F. Uddin et al. showed experimentally that addition of 15 wt% silica nanoparticles (Nanopox F400) in diglycidylether of bisphenol A epoxy helped increase the Mode I and Mode II fracture toughness. Reduction in damage footprint was observed for low-velocity impact tests. Similar experimental studies have been performed that show improvement in fracture toughness and impact resistance by enriching the matrix with nanoparticles of different shapes and sizes. A linear elastic fracture mechanics-based virtual crack closure technique was used to simulate Mode I and Mode II fracture toughness double cantilever beam and end-notched flexure tests, respectively. The nodes in an finite element model are initially tied together with highly stiff virtual spring elements and are released when Mode I, II, and III components of strain energy release rate exceed the mixedmode fracture criteria. The fracture criteria compare the instantaneous fracture energy release rate with the critical fracture energy release rate values of the material under consideration using the power law.
