Calculating screw joints

The first part of this report deals with the behavior of preloaded bolted assemblies for which it can be assumed that the load applied to them is axial.

For this type of assembly, the additional stress borne by the bolt is always much lower than the applied stress and depends on the relative stiffness of the assembly components and the shape of the parts.

This phenomenon, which is characteristic of prestressed systems, is particularly interesting in the case of fatigue stresses, since, if sufficient prestressing has been installed, a judicious choice of the shape of the parts and their stiffness can greatly reduce the value of the alternating stress in the screw and thus ensure good fatigue safety.

In the second part, the latest models for calculating the stiffness of bolts and parts are presented and discussed. The calculation of stresses due to temperature variations is then addressed, as well as the problems of contact pressure distribution at the interface and the determination of the spacing between two successive bolts.