<p>In this paper, fracture mechanics was used in a bid to assess the stress and failure behaviour of Adhesively Bonded Composite Joints (ABJs). Thus, areas of high stress concentrations and probable failure sites were determined, to allow for design improvements and maintenance plan. The Stress Intensity Factor (K) is observed to rise as a straight line along the joint, suggesting a higher probability of crack initiation and propagation. Using the K values, comparisons were made with the fracture toughness (K_IC) to determine potential failure zones, which were found to be between 57.14&#xa0;mm and 100&#xa0;mm along the joint. From the study, it can be deduced that analytical formulations and fracture mechanics principles can be used in the assessment of stress distribution and failure behaviour of the ABJs. In light of these findings, there is a need to address stress changes and failure modes in order to make the ABJs more dependable and functional. To enhance the novelty of the study and to provide a novel approach to this traditional problem, an advanced simulation technique, Particle Swarm Optimization (PSO) algorithm was employed to enhance, compare and validated the result by predicting the failure points in the ABJs using the Stress Intensity Factor. The study was able to confirm the accuracy of the original and simulation technique. Finally, the study gives valuable recommendations for engineers and researchers working on design and analysis of composite structures to further improve efficiency of composite joints.</p>