ORIG I NAL AR TI CLE Fatigue damage and life evaluation of thick bi-material double strap joints for use in marine applications Rahul Iyer Kumar 1 | Pankaj Jaiswal 1 | Wim De Waele 1 1 Ghent University, Department of Electromechanical, Systems and Metal Engineering, Soete Laboratory, Technologiepark-Zwijnaarde 46, 9052 Zwijnaarde, Belgium Correspondence Rahul Iyer Kumar Ghent University, Department of Electromechanical, Systems and Metal Engineering Soete Laboratory Technologiepark-Zwijnaarde 46 9052 Zwijnaarde, Belgium Email: Rahul.IyerKumar@UGent.be Funding information This research was carried out within the project “QUALIFY – Enabling Qualification of Hybrid Joints for Lightweight and Safe Maritime Transport”, co-funded by the INTERREG 2SeasMers Zeeën programme https://www.interreg2seas.eu/qualify and the Province of East-Flanders The present-day interest in the use of composite-steel joints in primary marine structures requires an in-depth knowl- edge of the fatigue performance of thick adhesive joints. This paper reports on experimental tests performed on com- pliant (i.e. thick and ductile) adhesive joints based on a two-component methyl-methacrylate adhesive in unaged and aged conditions. Bi-material double strap joint with thick adhesive bondlines are subjected to quasi-static and fatigue loading, during which, the specimens are monitored by Digital Image Correlation and Infrared Thermography tech- niques to evaluate the types and extent of damage that oc- cur in the joint during fatigue loading. The S-N curve of the aged joint is evaluated along with it’s fatigue limit. It is found that the unaged specimens fail due to cohesive damage, hackles and disbond at the adhesive-adherend in- terface and the aged specimens failed due to delamination within the composite. The specimens that survived fatigue loading showed similar residual strength as specimens that were not fatigue loaded. KEYWORDS Marine, Offshore, Adhesive, Fatigue life, Damage evaluation, S-N curve, Residual strength 1