Mechanical Properties of Threaded Regions in an Eyebolt and an Eyenut

Abstract

Mechanical properties such as load distribution and stress concentration in the threaded regions of an eyebolt and an eyenut are analyzed using the finite element method (FEM) which deals with elastic contact problems, where the "regularization method" is incorporated into stiffness matrices to avoid the singularities involved. Unlike a conventional bolt-nut connection, both external and internal threads in eyebolt and eyenut connections are in tension. Accordingly, it is considered that they might exhibit different mechanical properties. A single eyebolt or eyenut model is treated, and the external force is applied as gravity force corresponding to the allowable load specified in JIS so that the effects of the block shape can be examined by changing its height and diameter. Thus, the influences of the friction on the pressure flank, material properties and nominal diameter of threads upon the load distribution and stress concentration are evaluated for both an eyebolt and an eyenut. Furthermore, an elementary calculation method for load distribution is presented and compared with FEM.