Analysis of the Influence of Geometric Parameters on the Stress Distributions in Adhesively Bonded Scarf Joints Using 2D Models Under Elastic Assumption

Abstract

The scarf joint is a usual experimental assembly employed to analyze the mechanical behavior of an adhesive. In fact, using a unique type of bonded assembly with a classic tensile testing machine, various tensile-shear loadings of the adhesive can be applied by changing the value of the scarf angle. In this paper, accurate numerical analyses of the stress distributions within the adhesive in scarf joints under elastic assumption using 2D models are developed. Numerical results underline the influence of the adhesive thickness and mainly the influence of the scarf angle on the edge effects, and confirm the presence of an optimal scarf angle associated with very low stress concentrations. Moreover, the use of a suited elastic limit for the adhesive, defined from the two stress invariants, hydrostatic stress and von Mises equivalent stress, allows the more stressed parts of the adhesive with respect to the scarf angle to be defined. These results also underline the possible influences of the edge effects on the experimental results, i.e., possible crack initiations close to the free edges of the adhesive for some scarf angles. Finally, it is shown that a little modification of the free edges of the adhesive (a so-called “cleaning”) can strongly reduce the influences of the edge effects and thus can improve the experimental results for a wide range of scarf angles.