Load distribution between threads in threaded connections

Threaded connections are commonly employed in axial load-bearing equipment and pressure vessel components. There are a number of parameters that affect the load distribution between the threads and the stress concentration at the thread roots. These include the thread form, the thickness of walls supporting the threads, the pitch of threads, number of threads engaged, and the boundary conditions. In this paper, the influence of these parameters on the load distribution between threads is reported. Load distribution analyses in threaded connections is performed by analytical and by finite element methods. Square and buttress-type threads have been considered. Three-dimensional nonlinear finite element analyses on threaded connections have been performed using MSC/NASTRAN finite element code. The effect of clearance between the nonmating faces of threads as well as the presence of a flexible media between the mating faces of threads are investigated.