Cumulative static strength of tightened joints bonded with anaerobic adhesives

This paper deals with the static strength of mechanically tightened joints augmented with anaerobic adhesives. Tests were performed on a variety of specimens distinguished by fairly homogeneous (annular butt joint) or realistically inhomogeneous (threaded, cylindrical and double lap joints) working conditions over the bondline. For each geometry, the strength of the dry (unbonded) joint was compared with the strength of the joint bonded with an assortment of anaerobics. The results indicate that the strength of all joints (bonded and unbonded) increases with the contact force. When strong adhesives (retainers) are used, the overall strength approximately equals the sum of friction and adhesive strengths, taken separately. When weak adhesives (threadlockers) are adopted, the superimposition of effects grossly overestimates the measured strength. A micromechanical model is proposed that explains the observed macroscopic behaviour.