Designing bonded joints by means of the jointcalc software

This paper describes the theoretical framework, the experimental background and the software implementation of the computer package JointCalc for the strength analysis and design of adhesively bonded joints. Developed by Henkel AG in collaboration with three Italian Universities, JointCalc was designed to be accessible to non-experts, intuitive for occasional users and also general enough to include most of the joint configurations encountered in practice. For the calculation of adhesive stresses, JointCalc implements the analytical elastic solutions available in the literature for the fundamental joint geometries (single and double-lap joints, single and double-strap joints, peel joints and cylindrical joints). A key aspect of JointCalc is the experimental failure criterion adopted, represented by an admissible region in the peel-shear stress plane. The implementation required the creation of an experimental database, specifically built for the set of 14 adhesives (mostly epoxies) considered. A distinguished asset of JointCalc is its intuitive graphical interface that enables the user to choose the desired joint configuration, input the data and examine the results in a straightforward way. Since its appearance in 2003, JointCalc has been applied to the design of bonded assemblies covering a wide spectrum of industrial applications. Three of those applications (a seat back mounting, a shear punch solenoid and a screening device) are presented at the end of the paper as case studies. The disclosed data show that, provided that thoughtful engineering judgement is applied to idealize the real joints, JointCalc strength predictions closely match the experimental findings.