Abstract
This study dealt with thermal stresses and delamination growth in scarf joints under uniform temperature change by photoelastic measurement and a two-dimensional finite elementan alysis. The adherends were aluminum plates and an adhesive layer was modeled and manufactured from an epoxide resin plate. Adherends and epoxide resin plate were bonded using a heat setting and one component type adhesive. The adhesive was cured at high temperature and cooled to room temperature. The thermal stress was then generated in the scarf joint during temperature change and measured by the photoelastic experiments. After that the scarf joints were cooled stepwise, delamination growth from the edge of the interface was measured. It was confirmed that the delamination initiated from the edge of the interface was not the obtuse angle side, but the acute angle side. When the scarf angle was 90 degree, i.e., in adhesive butt joints, the resistance against the delamination was minimum. The thermal stresses in the scarf joints with thin adhesive layer were also analyzed. It was expected that the thermal strength increased with a decrease of an adhesive layer thickness. The stress singularity near the edge of the interface was calculated from the stress distributions in the joints with different scarf angles. As a result, the stress singularity in the scarf joints under thermal loads was quite different with that under mechanical tensile loads.
