Comparative Evaluation of Single-lap Joints Bonded with Different Adhesives by Cohesive Zone Modelling

Structures built from several components require some means of joining. In this context, bonding with adhesives has several advantagescompared to traditional joining methods, e.g. reduction of stress concentrations, reduced weight penalty and easy manufacturing. Adhesives can be strong and brittle (e.g., Araldite® AV138) or less strong and ductile (e.g., Araldite® 2015). A new family of polyurethane adhesives combines high strength and ductility (e.g., Sikaforce® 7888). In this work, the performance of the three above mentioned adhesives was tested in single-lap joints with varying values of overlap length (LO). The experimental work carried out is accompanied by a detailed numerical analysis by Finite Elements, based on Cohesive Zone Models (CZM). This procedure enabled detailing the performance of this predictive technique applied to bonded joints. Moreover, it was possible to evaluate which family of adhesives is more suited for each joint geometry. CZM revealed to be highly accurate, except for largely ductile adhesives, although this could be circumvented with a different cohesive law.info:eu-repo/semantics/publishedVersio

Comparative Failure Assessment of Single and Double Lap Joints with Varying Adhesive Systems

Joining by adhesively bonded methods is being increasingly used in the design of mechanical structures, because of the significant benefits of this technique compared to the traditional ones. Commercial adhesives range from strong and brittle (e.g., Araldite® AV138) to less strong and ductile (e.g., Araldite® 2015). A new family of polyurethane adhesives combines high strength and ductility (e.g., Sikaforce® 7888). This work compares the tensile performance of the three aforementioned adhesive systems in single and double lap aluminum joints with varying values of overlap length (LO). A cohesive zone modeling (CZM) numerical analysis was carried out to analyze through-thickness normal and shear stresses in the adhesive layer, to study the CZM damage variable and to predict the joint strength. A comparison was also performed with simple analytical models. The stress and damage variable analyses helped in understanding the differences between adhesives in which pertains to the failure process and joint strength. The proposed work also enabled concluding that the CZM predictions are typically accurate, and which family of adhesives is more suited for each joint configuration, with clear advantage for the Sikaforce® 7888. As a result of this work, design guidelines were proposed for adhesively bonded joints.info:eu-repo/semantics/publishedVersio