Effects of Pretension in Bolt for a Slewing Bearing

Abstract

This thesis is to check to bolt pretension for high duty bolted joint in the slewing ring. The bolted joint in the slewing ring is of special type the loads acts off axis of the bolt. For this kind of bolted joint, there is no direct theory. Most of them are based on experiments and are empirical. Some is also based on standards and experience. In the recent years, some finite element simulation has been done by some researchers. In this thesis, a finite element model was made using ANSYS WORKBENCH and an analytical formulation was used to find the work load on the bolt and then applied it in the WORKBENCH simulation and the result was satisfactory.The main task included in this thesis is to investigate the effect on the fatigue life of bolt with reduced pretension. This was also done and the result was satisfactory.Another task was to investigate the effect of plastic material behavior if time is allowed. This task was not addressed here due to time limitations.Other software used for this thesis was AUTOCAD INVENTOR. This was used to develop the model and later the model was analyzed in the WORKBENCH.The loads which act on the slewing bearing in this case comes from load history of the crane. A FORTRAN CODE was written using stiffness method to get loads on the ring from load history.Few recommendations for future work with this topics has also been attached at the end.