How to improve static and fatigue strength in press-fitted joints using anaerobic adhesive

This study is focused on the static and fatigue strength of interference-fitted connections supplemented with anaerobic adhesive (hybrid joints). Through axial release tests, it is demonstrated that the addition of the adhesive always improves the performance of the joint. The main achievable benefits can be summarized in (a) the possibility of increasing the load transfer capability with the same joint geometry and (b) reducing both the weight and the stress field of the joint with the same load transfer capability. The objective of the study is to provide some relevant information on the static and fatigue strength properties in case of both steel–aluminium components (mixed hybrid joints) and steel–steel components (steel hybrid joints). Furthermore, the authors provide some design formulae useful to predict the releasing force (the strength of the joints) both under static and dynamic conditions. Relevant improvements can be obtained using the anaerobic adhesive in terms of releasing force, which increases at least of 40 per cent. The proposed results derive from a collection of 200 experimental tests performed by the authors on a high-strength, single-component adhesive, which cures anaerobically (LOCTITE 648®).