Tension-tension fatigue behavior of ductile adhesively-bonded FRP joints

The tension-tension fatigue behavior of ductile adhesively-bonded double-lap FRP joints was experimentally investigated. An acrylic adhesive, which was in the rubbery state at ambient temperature, provided the joint ductility. The fatigue degradation of the joints was characterized by the cyclic energy dissipation, cyclic stiffness, cyclic creep displacement and self-generated temperature. The effects of elevated temperature on the joints’ static tensile and pure creep behaviors were also investigated. All joints failed in the adhesive layer at almost the same failure displacement, independent of the loading history (static, creep, fatigue, and temperature loading) due to the stretching of the adhesive’s molecular chains until the primary bonds failed. Fatigue failure was driven by cyclic creep; the cyclic creep displacements were accelerated mainly by the damage caused by fatigue at high load levels and by the damage caused by creep and self-generated temperature at low load levels.