Mixed-Mode Cohesive Fracture of Adhesive Joints based on Energy Balance Method

Adhesively bonded joints are preferred over the conventional methods such as riveting, welding, bolting, soldering and etc. Some of the main advantages of adhesive joints are the ability to join dissimilar, weight reduction, fabrication of complicated substructures and etc. In the aerospace industry, the adhesive joints or adhesive repair has been used. Adhesive joints usually break down through the crack initiation and growth, and therefore fracture mechanics theory is very helpful for studying fracture behavior of adhesively bonded joints. There are mainly two types of failure in adhesive joints: cohesive fracture and adhesive (interfacial) fracture. As a part of experimental efforts, mode I, mode II and mixed-mode cohesive fracture experiments with internal cracks have been performed using modified Arcan fixture by varying the loading angle. Also different crack lengths are applied into the adhesive. The overall aim of this study was to obtain critical energy release rate of adhesively bonded joints, using crack growth based on the energy balance method. The adhesive considered here is the PARMIX (B), a two part (Resin & Hardner) epoxy basic and a high strength adhesive which is widely used for bonding structures in aerospace industries and the aluminum-7075 has been used as Adhered. To compare the experimental data with finite element analysis results, modified Arcan specimen studied numerically by using Modified Virtual Crack Closure Technique (MVCCT) with the help Finite element software ANSYS. The comparison shows a good agreement between numerical and experimental results.