Analysis of crack propagation in mode-II in adhesive composite material/aluminum joints and extension of the experiments to effects of nanosilica on fracture toughness of adhesive

Assessment and evaluation of fracture characteristics are very important in adhesive joint for achieving a safety mode. In the present research fracture has been investigated in mode-II in adhesive composite material/aluminum joints. To achieve this aim ENF test have been performed for pure adhesive in different initial crack lengths to record load-displacement curves and critical strain energy release rate (SERR) has been obtained via Compliance Calibration Method (CCM) and Simple Beam Theory (SBT). Experimental resistance curves (R-curve) obtained by CCM and SBT showed good agreement. Then the experiments have been extended to adhesives that modified by nanosilica to determine how the nanoparticles affect adhesive toughness. The fracture energy increased to about 1297 J/m2 (60.3%) for the adhesive with 8 wt% of silica nanoparticles. Finally scanning electron microscopy (SEM) have been used to examine the fracture surfaces.