Characterization of the mode I fracture energy of adhesive joints

This investigation was aimed at improving the calculation of the Mode I fracture energy, GIC, of adhesive joints by incorporating the elasticity of the adhesive layer. It was also aimed at proposing ways to improve the calculation of GIC over the existing standard for the measurement of that material property.Our experiments were performed with a variety of aluminum specimens bonded with a large number of different adhesives in various thicknesses. All specimens were tested under mode I loading. In calculating GIC, it is common to neglect the properties of the adhesive layer, especially when the compliance of the system is considered. The validity of this attitude was tested in the present study, and it was found to be in accord with the experimental results but only for joints bonded with a relatively thin layer of adhesive. A method for improving the calculation of the fracture energy of standard specimens, using a theoretical model for the compliance is proposed. This method comprises all the adhesive parameters and is appropriate for linear elastic joints.