COMPARATIVE EFFICIENCY OF FINITE ELEMENT MODELS OF CFRP BONDED JOINTS

摘要

Bonded joints are a common system of connection in aeronautical and space structures. By using adhesive materials, many structural parts made of carbon fiber reinforced plastic (CFRP) can be effectively linked. A specific issue in this type of joints is constituted by the evaluation of the stress and strain fields in the adhesive material. Obviously, experimental works can be carried out in laboratory in order to identify the ultimate load value, but numerical methods based on finite element structural models can be very useful in describing the stress and strain response for each load step. In this approach, an issue regarding to the accuracy of the several finite element discretizations used to describe the joint is under debate. In this paper a parametric study aimed to compare the accuracy of several modelizations of a bonded joint consisting of two parts of CFRP bonded by a layer of epoxy film adhesive will be presented. All the finite elements models developed are three-dimensional and they include the geometrical nonlinearity of the single lap behaviour with linear elastic materials in the adherend and the adhesive. Results obtained with different mesh sizes and element types are compared with the available experimental data. Finally in one model the effect of material nonlinearity in the adhesive is analyzed using a traction-separation linear damage model with cohesive elements.