VISCOELASTIC AND VISCOPLASTIC STRESS-ANALYSIS OF ADHESIVE JOINTS

The viscoelastic and viscoplatic effects in an adhesively bonded joint are very important to understand. Most of the adhesives used in structural applications exhibit some viscoelastic-viscoplastic behaviour, especially at high temperatures and high stress levels. The redistribution of stresses and strains that occur in joints during the viscoelastic-viscoplastic deformation influences the strength of the joints considerably. At low load levels a linear viscoelastic material model may be applicable, and at higher load levels both linear viscoelastic and non-linear viscoplastic material models are active at the same time. This paper presents results from the stress analysis of single lap joints, both with and without a crack, and with viscoelastic and viscoplastic adhesives. The influence of the stress redistribution on the failure load of the joint is discussed, as well as a 'rule of thumb' which can account for the viscous effects in the engineering design. The influence of flaws in the joints is also discussed. © 1990.