Properties of bolted connections

 

The purpose of nuts and bolts is to push 2 or more parts together with a certain force. Bolts behave like springs, up to the yield point a bolt remains elastic, from the yield point the bolt permanently deforms and becomes longer. The bolt breaks at the breaking point. 0,2% yield strength Rp0.2 (N/mm2)
To properly determine the yield point, one must just exceed the yield point to recognize this point. At this point there is a permanent deformation in the bolt of approximately 0,2%. This point of permanent deformation is referred to as 0,2% yield strength. If bolt is exposed to further increasing force from this moment on, the permanent deformation of the bolt (read: length) will increase. This increase reaches a maximum at which point the bolt will fail under this expose force. Finally, the breaking point of the bolt was reached.