SIF evaluation and stress analysis of drillstring threaded joints

摘要

In a study by Tafreshi and Dover [1-3] stress analysis of drillstring threaded joints under axial, bending and torsion loadings was carried out using the finite element method. Stress concentrations were determined on a variety of threaded jointsin order to predict the fatigue life of these components. Here some of those results are presented in more detail. In this study it is shown that in the case of bending, axisymmetric solid elements with non-linear, asymmetric deformation with fourierinterpolation can be employed which reduces the computational time and modelling in comparison with the full three-dimensional analysis. Quasi semi-elliptic circumferential internal and external cracks in tubes with the same dimensions of the pins orboxes of a series of joints are modelled and analysed using the J-integral method. Thc result of this fully three-dimensional crack analysis shows the same trend as experimental [3] and published results [4].