Adhesively bonded lap joints from pultruded GFRP profiles. Part III: Effects of chamfers

Quasi-static axial tension experiments were performed in a laboratory environment on epoxy bonded, balanced double-lap joints composed of pultruded GFRP flat profiles. The parameters investigated were the overlap length (from 50 to 100 mm), the adhesive layer thickness (1 and 3 mm) and the degree of chamfering of the adherends. The measured axial strain profiles in the joints correlated well with numerical results obtained from a 2D finite element analysis. Failure initiation and propagation always occurred in the outer fiber-mat layers of the adherends. Chamfering reduced and smoothed the through-thickness tensile and shear stress peaks towards the chamfered joint edges. However, joint strength was not significantly improved by chamfering. The joint strength was predicted by means of a quadratic shear–tensile failure criterion for a failure location in the outer fiber-mat layer of the pultruded adherends and compared well to the measurements. The adhesive layer thickness had an insignificant influence on the stress–strain distributions along the overlaps and joint strengh.