Experimental analysis of the mechanical behaviour of a thick flexible adhesive under tensile/compression-shear loads

Flexible adhesives, characterised by low modulus, and large strains at failure in comparison with usual structural adhesives, present various advantages for assembling large scale parts and dissimilar materials while for instance limiting the influence of thermal stresses. Thus various applications can be found in automotive, aeronautic and building industries. The single-lap joint is widely used to characterise the behaviour of adhesively bonded assemblies, but it is associated with a complex tri-dimensional stress state especially close to the free edges of the adhesive. Moreover, in order to develop accurate numerical models for adhesively bonded assemblies, experimental results under various loading paths have to be analysed. The objective of this paper is to characterise the behaviour of a thick flexible adhesive (Sikaflex®-265) under different monotonic tensile/compression-shear loadings. For this purpose, a modified Arcan fixture has been designed to limit stress concentrations in order to characterise the mechanical behaviour of the adhesive up to failure. Results allow defining the load-displacement envelopes characterising the adhesive at failure under multi-axial loading conditions. Finally, the influence of some parameters on the mechanical behaviour of the assembly was analysed, such as the nature of the substrate material (ABS or aluminium), the geometry of the substrates and the strain rate.