Fabrication and curing conditions effects on the fatigue behavior of a structural adhesive

This paper investigates the effects of degassing, curing and post-curing conditions on the tensile quasi-static and fatigue behavior of a cold-curing structural epoxy adhesive. Quasi-static experiments performed at standardized and high displacement rates similar to those imposed to the material under fatigue loading, in order to derive comparable results from both loadings, and tensile-tensile fatigue tests at a fixed stress ratio, were carried out. Digital image correlation, video extensometer, thermal camera, digital camera and microscope were used to record the evolution of the strain and temperature, and assess the damage evolution during and after loading. The results shown that degassing can improve the material behavior when curing at ambient temperatures, since it assists the removal of several small voids from the bulk adhesive. However, when curing the material at high temperatures, immediately after mixing, the degassing does not offer any advantage, and the material's long-term performance decreases.