On the bondline thickness effect in mixed-mode fracture characterisation of an epoxy adhesive

ABSTRACT

In-situ testing as a method for fracture characterisation of adhesives has received increased attention in recent years. Previous studies show that the fracture properties of the adhesive determined by in-situ testings are influenced by the bond-line thickness. In this work, the effect of the bond-line thickness on the fracture properties of a two-component epoxy ductile adhesive under mixed-mode loading is investigated. Double Cantilever Beam (DCB) and Mixed-Mode Bending (MMB) tests with different mixed-mode ratios were conducted. A recently proposed data reduction technique based on the J-integral approach was employed for the determination of strain energy release rate (SERR) of the epoxy adhesive under mixed-mode loading. Results showed that the fracture properties – particularly critical SERR G_C- in in-situ testing is not only a function of bond-line thickness but also the ratio of mode mixity. Increase in the bond-line thickness led to an increase in G_IC under pure mode I tests up to 40%. However, this trend was not observed under mixed-mode loadings due to the different type of constraints existing in the MMB tests.

KEYWORDS:

• Mixed-mode failure
• strain energy release rate
• J-integral
• adhesive thickness
• ductile adhesive

Acknowledgements

The authors wish to thank Huntsman Germany GmbH for providing us the adhesive Araldite 2015.

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.