Calculating screw-mount assemblies - Assembling thin layers of flat parts. Part 2

In the first part of [BM 5 564] , we presented the dimensioning at failure of connections working in shear. We also discussed the calculation of load transfer between the rows of fasteners in a joint bar, showing the complexity of the problem when bolt tightening is significant and the resulting frictional load transfer is no longer negligible.

In this second part, we focus on the fatigue calculation of assemblies working in mat-shear, then show that service life can be considerably increased by installing sufficient prestressing. At present, little is known about this essential problem, and there is no proven method of prediction. On the other hand, recent experimental results clearly show that service life can be increased tenfold, or even a hundredfold, by applying appropriate bolt tightening, and we propose a simple method for determining the prestressing force to be installed.

To complete this presentation, we deal with the calculation of load distribution between fasteners in the case of any arrangement and loading, and with the problem of assembly stability.