A method for simulating the behavior of a bonded joint of two composite material parts with an adhesive material layer. The method includes the steps of a) providing a Finite Element Model with all the relevant information for analyzing the structural joint; b) providing a calculation model for calculating the deformations of the adhesive material layer when it is subjected to tensile/peel and shear stresses, including a plastic behavior of the adhesive of a linear type under tension/peeling and of a non-linear type under shearing; and c) simulating the behavior of the bonded joint by applying the calculation model to obtain the failure indices of each failure mode. A system which is useful as an aid in the design of the structural joint using a computer-implemented Finite Element Model of the structural joint.