The Behaviour of Fasteners under External Loading : Force Ratio of Threaded Connections

Abstract

In the design of fasteners subjected to an external service load, it is very important to know the relationship between bolt tensile load and service load and to assure a good tightening. However, there are many difficult points in the analysis of fasteners, because the shape of threaded parts of bolts and nuts is very complex and a threaded fastener is, from a view point of the theory of elasticity, equivalent to a contact problem of many elastic bodies. This paper introduces a finite element technique to numerically analyze the the threaded fastener subjected to external loads. As concrete examples of standard threaded fasteners, the results for the force ratios of the through bolt, the tap bolt, the stud and the T-type flange are numerically obtained by using an axi-symmetric and a three-dimensional model.