Topological optimization of the adhesive of bonded joints formed by the superposition of two adherents using the cohesive zone model as failure criterion.

This research presents a study of the structural behavior of the adhesive material of a bonded joint formed by the overlap of two adherents, known as Single Lap Joints (SLJ). It is a type of structural joint that is simple to perform and, therefore, widely used. However, this type of joint presents a non-uniform distribution of efforts along its overlapping. This behavior is the result of the topology of this joint, which receives the load eccentrically in relation to its longitudinal axis. Computational simulations were carried out, using the finite element method, in which the joint responses to regular loading were evaluated. In this study, various overlap configurations and adhesives with ductile and brittle behavior properties were used. The compatibility of the generated models was verified with experimental results available in the literature. Such simulations were carried out, first, in the presence of failure criteria, according to a Cohesive Zone Model (CZM). The results were in alignment with the references used, demonstrating the efficiency of the modeling and its applicability in the development of technical and scientific research. In a second phase, a topological optimization process, Bi-directional Evolutionary Structural Optimization (BESO), was implemented, in the adhesive region, concurrently with the studies of stresses and CZM failure criteria. This procedure made it possible to measure the effects on the behavior of the SLJ joint in the face of the distribution of adhesive material according to topological optimization criteria. The results showed a concentration of adhesive material in the regions of the joint ends, more uniform stress distribution and the possibility of using the material more efficiently. In addition, this optimization method has the potential to aggregate scientific concepts and technologies in complex study conditions. The BESO optimization process is a structural analysis tool that, coupled to CZM model, makes it possible to obtain a bonded joint behavior, capable of offering better use of materials in terms of consumption, stress distributions and loading absorption.