The effect of viscoelasticity of adhesives on shear stress distribution in a double-lap joint using analytical method

Abstract In this paper, the effect of viscoelasticity of polymeric adhesives on shear stress distribution in the adhesive layer of a double lap joint under shear is studied. The postulated model is composed of three single isotropic adherend layers joined by polymeric adhesives. Each adherend layer is assumed to behave as linear elastic. The results are deduced for epoxy adhesive, and hence, 3-parameters solid model is used to model the viscoelastic behavior of the adhesive layers. The derived equilibrium equations are transformed into Laplace domain and are solved using residue theorem. Results show that for a step load of P 0 = 100 N, the peak shear stress in the epoxy adhesive layer reduces to its steady value over a time span of almost 1000 s. Moreover, if the applied load is raised gradually from zero to its final value of 100 N in seconds, its rate of increase has a direct effect on the peak shear stress developed in the adhesive layers. The influence of the adhesive thickness, as well as the effect of adhesive viscosity and its shear modulus (in terms of their ratio), on shear stress distribution in the adhesive joint are also investigated. Keywords: adhesive jointdouble-lap jointspolymeric resinsviscoelasticityresidue theorem