Key Engineering Materials Vols. 340-341

Abstract: The adhesive fatigue strength was investigated by performing repeated tensile lap shear experiments of an aluminum single-lap joint bonded with highly ductile acrylic adhesive. In load-controlled fatigue tests, progressive transverse shear deformation of the adhesive layer took place, and it led to the final fracture of the joint. The fatigue strength becomes higher with increasing loading speed, especially at low-cycle fatigue region. From experiments on shear-prestrained specimens, it was found that the prestrain does not affect so much the fatigue life. In order to discuss the behavior of progressive shear strain accumulation (viscoplastic ratcheting) of adhesive under cyclic loading, the numerical simulation of ratcheting was conducted using a constitutive model of elasto-viscoplasticity for the adhesive.

Abstract: The effects of temperature and strain rate on flow stress of a highly ductile acrylic adhesive were investigated by performing tensile lap shear experiments on an adhesively bonded single-lap joint, as well as torsion experiments on a tubular butt-joint at temperatures ranging from 10 to 40oC at various shear strain rates. The flow stress decreases considerably with decreasing strain rate and with temperature rise. The stress-strain responses under multi-axial stress conditions were also examined by performing combined tension-torsion experiments on the butt-joint. A constitutive model of temperature-dependent elasto-viscoplasticity that describes multi-axial stress-strain behavior of the adhesive is presented.