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Abstract The metallic materials bonding using structural adhesives has become an increasingly used process, presenting advantages when compared to other fastening methods such as screws and rivets. The aim of this paper is the numerical evaluation of bonded joints with combined loading (traction and shear) using the finite element method, comparing the results obtained with the experiments performed at the same configurations. Considering adhesive joints with the same bonded area, but with different linear dimensions, the mechanical strength may be different, which characterizes the shape factor. In this way, the analyzes considered the bonded area shape factor in nine different configurations, being modified both the height and the width of the joint, considering two points of force application for each group. For the numerical simulation, the cohesive zone models (CZM) were used, which use the concepts of linear elastic fracture mechanics (LEFM). These models consider that one or multiple interfaces or regions of fracture may be artificially introduced into the structures, which is done through the separation-traction laws. For this purpose, DCB (double cantilever beam) and ENF (end notched flexure) tests were performed, measuring this way the essential cohesive properties to the numerical modeling, especially the critical energy release in I and II modes (normal and shear, respectively). The influence of some cohesive properties on the maximum load of the bonded joint was investigated. The good numerical and experimental concordance in different configurations studied confirms that the CZM provide consistent results with the bonded joint experiments for the presented conditions of adhesive thickness, surface treatment and load application point, not only in single lap joints, but also in combined loading joints, whose investigation was done in this work. [ABSTRACT FROM AUTHOR]

Abstract: The present study is concerned with the failure analysis of a special type of adhesive corner joint, which is essentially a rectangular cantilever bonded to a support. A shape factor that allows correlating the static strength of two joints with different geometries is proposed. The relation is valid for adhesives with brittle–elastic behaviour and highly resistant adherends. Therefore, only a few tests performed in particular joint taken as reference are necessary for assessing the structural integrity of any similar joint with arbitrary geometry. Results from experiments performed in ASTM 1020 steel tee joints with different bonding areas are compared with model prediction showing a good agreement. The adhesive was an epoxy/ceramic composite used in the oil industry for the repair and protection of metal surfaces subjected to corrosion and chemical attach. [Copyright &y& Elsevier]

Abstract: In this paper it is proposed a phenomenological framework to perform the failure analysis of a family of adhesive single lap joints. The theory is conceived for adhesives with quasi-brittle behaviour and highly resistant adherends. The main goal is to predict the rupture force using model equations that combine enough mathematical simplicity to allow their usage in engineering problems with the capability of describing a complex nonlinear mechanical behaviour. The material constants that appear in the model equations are identified for an adhesive/adherend system consisting of ASTM A36 steel plates bonded with an epoxy/ceramic composite. Results from experimental tensile testing of joints with different bonded areas were compared with model prediction showing a good correlation. [Copyright &y& Elsevier]

Abstract: The present work is concerned with the study of the influence of adhesive layer thickness on the mechanical strength of axially loaded aluminium–epoxy butt joints. The main goal is to predict the rupture force using model equations that combine enough mathematical simplicity to allow their usage in engineering problems with the capability of describing a complex non-linear mechanical behaviour (three-dimensional state of stress; possibility of cohesive failure, of adhesive failure or mixed failure, depending on the geometry of the joint, on the adhesive strength and on the interaction between surfaces). The predicted values of the rupture force for different values of the thickness of the adhesive layer are compared with experimental data, showing a good agreement. [ABSTRACT FROM AUTHOR]

While research has explored surface treatment effects on fracture energies in pure modes (I or II), there is a lack of research under mixed-mode loading. The aim of this paper is to investigate the influence of surface treatment approaches on the fracture behaviour and fracture energy of adhesive joints at different loading modes. To achieve this, double cantilever beam (DCB) adhesive joints were manufactured considering two different surface treatment methods namely grit blasting and mechanical bristle blasting. The joints were subjected to five different mode mixities. Fracture energy for each tested condition was calculated based on a compliance-based approach. The fracture energies in mode I reached an increase of 55 % when grit blasting surface treatment was applied, while for mode II the fracture energy reached a value three times higher for mechanical bristle blasting surface treatment, both energies from the mixed mode tests. The failure mechanisms were also evaluated for joints with different surface treatments as a function of loading mode. In all tested conditions, a cohesive failure mode was observed; however, the results underscore the substantial influence of the surface treatment method on the fracture energy of adhesive joints. This is attributed to the distinct failure mechanisms observed under varying surface treatment conditions. [ABSTRACT FROM AUTHOR]