Adherend effect on the peel strength of a brittle adhesive

Peel tests are widely used to characterize the peel strength of bonded joints and control adhesion quality. There are various configurations of peel test, such as the T-peel test, peel testing at 180°, the floating roller peel test, and the climbing drum peel test. These methods have been widely used mainly in the aeronautical industry, as a way of assessing the peel strength of metallic joints. However, with the growing use of composite materials in industry, it is necessary to characterize bonded joints with these materials when subjected to peeling loads. In this research, the adherend effect on the peel strength of a brittle adhesive is experimentally studied using the floating roller peel test with the aim of evaluating how adherend changes affect adhesion properties of brittle adhesives and also to assess the viability of using the floating roller peel test in composite-to-composite and composite-to-aluminum joints, as well as make a comparison with aluminum-aluminum joint performance. It is also intended to prove the applicability of this test for quality control of adhesion and determination of peel strength in joints with composite materials. The results show the Araldite® AV138 performance falls within the characteristic values of peel strength of other structural adhesives, particularly when composite adherends are concerned, and with reasonable repeatability considering it is a brittle adhesive.info:eu-repo/semantics/publishedVersio

A new structural two-component epoxy adhesive: Strength and fracture characterization

30th International Conference on Flexible Automation and Intelligent Manufacturing (FAIM2021) -15-18 June 2021, Athens, GreeceIn the past decades, adhesive technology has been useful in order to solve numerous issues related with conventional joining techniques (bolting, riveting and welding). Several advantages of adhesive bonding can be pointed out, such as low weight (relevant in the automotive and aeronautical industries), capability to resist to adverse environmental conditions, lower manufacturing costs and possibility to join different materials. To predict crack propagation of an adhesive joint by advanced fracture mechanics-based techniques such as cohesive zone models (CZM) it is not enough to know the traditional mechanical properties, such as Young’s modulus (E), shear modulus (G), tensile strength (σf) and shear strength (τf). Actually, it is also mandatory to estimate the tensile (GIC) and shear fracture energies (GIIC). The purpose of this work is to carry out the mechanical and fracture property characterization of a new structural two-component epoxy adhesive. With this purpose, four tests which were conducted: tensile testing to bulk specimens, shear testing with thick adherend shear tests (TAST), double-cantilever beam (DCB) and end-notched flexure (ENF). With these tests, it was possible to determine the mechanical and fracture properties of the adhesive in tension and shear. Different data reduction methods were evaluated for the fracture properties. The test results agreed with the data provided by the manufacturer and will enable the design of bonded structures with this adhesive.The authors would like to thank Sika® Portugal for supplying the adhesive SikaPower® 1277info:eu-repo/semantics/publishedVersio