Fracture study of a ductile polymer-based nanocomposite weakened by blunt V-notches under mode I loading: Application of the Equivalent Material Concept

The onset of fracture is studied in a ductile epoxy-based nanocomposite containing round-tip V-notches both experimentally and theoretically under pure mode I loading conditions. Mechanical properties of the nano composite containing 0.1, 0.3, 0.5 and 1 wt% multi-walled carbon nanotubes (MWCNTs) are experimentally measured to find a desired amount of nanoparticles. Rectangular plates containing a central rhombic hole with four blunt V-shaped corners are utilized as the samples for fracture tests. Specimens with two different notch angles of 30 and 60 and various notch tip radii are tested under remote tension to obtain their load-carrying capacities (LCCs) experimentally. For theoretically predicting the experimental results, the Equivalent Material Concept (EMC) is reformulated and utilized. Two well-known brittle fracture criteria, namely the maximum tangential stress (MIS) and the mean stress (MS) criteria, are employed in conjunction with EMC for theoretical predictions. It is revealed that both the EMC-MTS and EMC-MS criteria could predict the experimental results well, without performing any elastic-plastic analyses of the nanocomposite specimens.