Constructive and experimental examination of reliability and robustness in dynamically stressed bolted joints

Abstract

Loosening and failure of bolts and nuts is, and has historically always been, a challenge for industries all over the world. This thesis examines the bolted connections of a local plough manufacturer (hereafter referred to as KvK). KvK has had challenges with loosening and failing bolts for several decades. The structure of this thesis is to first go through the bolting philosophies of KvK and then to look at bolt literature. These two will then be compared and an evaluation of the different variables in a bolted connection are described and analyzed. Changes in two variables, the bolt preload and the friction diameter, were evaluated theoretically. The change in preload was then simulated and then experimentally tested at the KvK test centre for validation. The results show a significant improvement in resisting loosening with increased preload. A discussion regarding the results, result validity and a conclusion follows. The thesis rounds out with suggestions for further work, references and appendixes.