Concentration of Cyclic Stresses in Preloaded Threaded Connections

Abstract

The results of the stress analysis of a threaded tubular connection, obtained by using a hybrid analogue‐numerical method, are discussed in the paper. The model enabled both the tooth loads and the local tooth fillet stresses to be calculated. In particular, the local stresses resulting from cyclic axial loading and preload are discussed in detail. It is shown that the stress concentration factor at the critical tooth of a preloaded connection varies as axial load is applied from zero to its maximum value. However, the ratio of the local stress range at the root of the tooth to the nominal average axial stress range at this tooth remains constant. It is demonstrated that preloading a threaded connection reduces the local stress range and increases the local mean stress in comparison with connections without preload subjected to the same cyclic loading.