Epoxy resins are widely used in various industrial applications. However, they are often vulnerable to brittle fracture especially in the presence of preexisting cracks. In order to improve their strength and toughness, researchers have suggested reinforcing epoxy resins by adding multi-walled carbon nanotubes (MWCNTs) which are known for their excellent stiffness and strength as well as their extraordinary electrical and thermal properties. Meanwhile, it is important to investigate the fracture behavior of the epoxy/MWCNT composites (often called nanocomposites).
Previous experimental researches dealing with fracture in epoxy-based nanocomposites are predominantly limited to pure mode I loading cases. Whereas epoxy components very often experience complicated loading conditions e.g. a combination of tension and shear loads. The aim of this research is to present some recent experimental results obtained from fracture tests on epoxy/MWCNT nanocomposites under mixed mode loading. First, a new test configuration designed for mixed mode fracture tests is introduced. The test set up is then simulated by finite element method and the crack tip parameters are extracted for different mode mixities. To assess the applicability of the proposed fixture, a set of experiments are performed on PMMA. The main experiments are then performed on nanocomposite specimens with different percent contents of MWCNT. The experimental results are presented and discussed in terms of different micro-mechanisms involved in fracture behavior of nanocomposites under mixed mode loading.