Mechanoluminescent visualization for considering effect of bondline thickness and overlap length on single lap joint

The study examines impact of bondline thickness and overlap length on the performance of single-lap bonded joints by analyzing the dynamic strain distribution using mechanoluminescence (ML) sensing. As the bondline thickness increased from 0.1 to 1.0 mm, the pattern of crack propagation from the top and bottom edges of the bonded region exhibited a marked transition toward rupture. Specifically, the differences in crack propagation behavior were visually identified near one or both bonding interfaces. Additionally, the impact of overlap length on failure modes in lap shear tests, including crack propagation and shear forces, was visually differentiated through ML. Despite its simplicity as a spray-on sensor, ML sensing demonstrated effectiveness in indicating mechanical behavior related to bonding design, such as bondline thickness and overlap length.