The effect of the crack/bondline seperation distance on the stress intensity factor for the opening mode - A three-dimensional finite element analysis and experimental work

Experimental work and a three dimensional FEA were carried out to study the effect of the crack/bondline separation distance on the stress intensity factor (SIF) of crack opening mode I for complete homogeneous, bonded similar and bonded dissimilar materials. The local SIF (K-I) has numerically been evaluated using the Ansys package program. A three-dimensional finite element analysis (FEA) model has been developed for specimens made of different homogeneous materials such as plexiglas bonded to similar material (plexiglas) with epoxy as a filler material and bonding of dissimilar materials such as plexiglas and white iron with epoxy. The number of elements along the crack front and crack tip has been considered and has been changed to determine the effects on the value of the stress intensity factors. The results for the stress intensity factors K, have been obtained using a linear elastic fracture mechanics (LEFM) approach. A good agreement regarding the behavior of SIF has been observed between the FEA and the fracture toughness experiments. The results indicate that the SIF increases as the crack/bondline separation distance increases. However, the experiments showed that the fracture toughness decreases as the crack/bondline separation distance increases.