A contribution to the qualification process of surface pretreatment methods: Sensitivity of mechanical tests to adhesion and delamination

ABSTRACT

Focusing the adhesive bonding of thermoset carbon fiber reinforced plastics (CFRPs) due to release agent residues on a surface pretreatment prior to the bonding process is inevitable to guarantee sufficient adhesion. Based on different material and process-related phenomena, a huge variety of parameters (e.g. treatment time) influence the treatment effectiveness. This often leads to intense parameter studies in which pretreatment methods are qualified by different mechanical tests and which require significant effort in terms of time and resources. Those qualification procedures are sometimes standardized by different and mostly company-specific standards. To increase the efficiency of this qualification process by increasing the general validity, this paper presents a comparison of different mechanical test methods (namely single lap shear test, floating roller peel test, double cantilever beam (DCB) test, and cross-tension test) in terms of their sensitivity to the detection of adhesion or delamination defects, even if they normally test different aspects of a joint. However, it could be found that the most common test – the single lap shear test – can only reveal large defect levels, while different tests, e.g. DCB test, show a good sensitivity for all investigated failures and others show intermediate performance.

KEYWORDS:

• Adhesive bonding
• composites
• destructive testing
• surface treatment

Acknowledgements

The authors would like to thank the Hexcel Composites GmbH, Stade, and the ChemTrend (Deutschland) GmbH, Hamburg, for the material supply.

Funding

The presented results were found within the project Qualivor (funding code 03FS15036) sponsored by the German Federal Ministry for Economic Affairs and Energy (BMWi) on the basis of a decision of the German parliament under the project management of the Project Management Agency Jülich (PTJ). The financial support is gratefully acknowledged.

Additional information

Funding

The presented results were found within the project Qualivor (funding code 03FS15036) sponsored by the German Federal Ministry for Economic Affairs and Energy (BMWi) on the basis of a decision of the German parliament under the project management of the Project Management Agency Jülich (PTJ). The financial support is gratefully acknowledged.