Abstract
This paper presents the fatigue properties of single lap bonded joints under cyclic tension shear loading. A newly developed rubber toughened epoxy adhesive was used. The effect of adhesive thickness on fatigue life of the joint was focused in this paper. Results are summarized as follows. 1) The static strength of the joint using this toughened adhesive is independent of adhesive thickness. For low cycle fatigue, the strength is not influenced by adhesive thickness as well. However, it affects the fatigue strength at a high cycle fatigue. 2) The fatigue failure surface changes according to the adhesive thickness although the failure modes are not dependent on the failgue life. 3) The relation between the fatigue crack velocity da/dN and the strain energy release rate ΔGT under combined modes seems to be affected by the adhesive thickness. 4) Fatigue lives of single lap joints having different adhesive thicknesses can be predicted using the individual, relation da/dN-ΔGT based on the Paris's law. 5) The relation between crack length in the adhesive layer and ΔGT under the same loading condition is influenced by the adhesive thickness. This is one of reasons for the effect of adhesive thickness on the fatigue life.
