On the sensitivity of bondline control specimens with respect to the detection of adhesion defects

ABSTRACT

Adhesive bonding is a highly efficient joining technology for the repair of fibre-reinforced plastics. However, in civil aviation, its application is currently limited to non-critical joints. In safety critical cases, certification authorities demand proof of sufficient bond strength for each individual joint. Today, there is no practicable inspection method that can provide this kind of evidence. Recently, a novel method has been proposed that may resolve this issue. This so-called Bondline Control Technology (BCT) is a new type of adhesion test that provides proof of bond quality and simultaneously serves as a robust surface pretreatment for adhesive bonding. The present study investigates on the capability of the BCT to detect adhesion defects. This is done by means of in-lab tests on bonded specimens with adhesion defects of defined severity. The detection sensitivity of BCT coupons (Bondline Control Specimens, BCS) is compared with double-cantilever beam specimens (DCB specimens), which are known to be particularly capable of detecting adhesion defects.

KEYWORDS:

• Adhesive bonding
• composites
• repair
• contamination

Acknowledgement

This is an article based on parts of research performed within the project FACTOR.

Disclosure statement

Several patent application are pending resulting from the work (WO 2018/233928 A1 “Method and device for inspecting a joining surface”, WO 2020/109395 A1 “Method for producing a test specimen”).

Data availability statement

The data that support the findings of this study are available from the authors with the permission of German Aerospace Center and Fraunhofer-Institut für Fertigungstechnik und Angewandte Materialforschung.

Additional information

Funding

This work was supported by the Federal Ministry for Economic Affairs and Energy of Germany [20W1520F and 20W1520G].