Design and Manufacture of Devices for the Testing of Adhesives and Adhesive Joints

The reliability of mechanical testing of adhesive joints is strongly dependent on the design and performance of the testing fixtures, jigs or apparatus used to manufacture and load the specimens. Inadequate devices design may introduce misalignment, parasitic stresses, and uncontrolled adhesive thickness, compromising the accuracy and repeatability of experimental results. This paper presents the design, development, and manufacture of a set of dedicated mechanical devices for the characterisation of adhesive joints, specifically targeting floating roller peel and butt-joint tensile testing. These devices will ensure that the testing laboratory is duly equipped and qualified to carry out the specified tests for both research activities and industrial applications. The proposed system comprises three main components: a floating roller peel fixture compliant with ASTM D3167, a modular jig for the fabrication of butt-joint specimens with controlled adhesive thickness, and a self-aligning apparatus for tensile testing of butt joints. The design process was guided by key mechanical requirements, including precise load alignment, minimisation of frictional effects, controlled kinematics, and robustness under repeated testing conditions. All components were developed using CAD modelling and manufactured through precision machining using structural steels and aluminium alloys. Particular attention was given to the control of geometric tolerances, alignment mechanisms, and load transfer paths, ensuring consistent specimen positioning and minimisation of secondary stresses during testing. The proposed devices provide a versatile and cost-effective solution for laboratory-scale mechanical testing, enabling improved repeatability and reliability of experimental procedures. Experimental validation was performed using epoxy and polyurethane adhesives with distinct mechanical properties, which experimental values are addressed in another paper. Overall, the presented design contributes to the standardisation and optimisation of experimental methodologies for adhesive joint characterisation, supporting more accurate and reproducible mechanical testing in engineering applications.