Ultimate behaviour of adhesively bonded FRP lap joints

This paper deals with a numerical investigation on double-lap and symmetrical single-lap joints subjected to shear/bending moment and axial force. The analysis has been developed using the theoretical model proposed by the author in [Ascione F. Mechanical behaviour of FRP adhesive joints: a theoretical model; 2007]. The mechanical behavior of the adhesive is modeled through two sets of independent interfacial springs capable of characterizing the normal and transversal interactions, respectively. The adherents are modeled following the hypotheses of the beam technical theory. The mathematical model is based on two fundamental hypotheses: the possibility to separate the shear-flexure problem from the extensional one; the total fracture energy is additionally broken down in a term relative to mode I of fracture (opening) and in a term relative to mode II of fracture (sliding). Five dimensionless parameters which influence the design problem of the joints are identified. Several examples of the ultimate domains of the interface between the adherents are also presented as well as comparisons with some results reported in literature.