Fatigue behaviour of oblique nozzles on cylindrical shells submitted to internal pressure and axial forces

In detailed analytical checks against fatigue failure, the local notch stress approach can be considered as one of the most advanced methods for predicting the fatigue behaviour of a mechanical structure. However, it is based on a detailed strength analysis, including macroscopic notch effects, of the real structure; e.g., at weld seams. In this paper, the fatigue behaviour of oblique nozzles on cylindrical shells submitted to internal pressure, axial force and combined loading is analysed according to these principles. Detailed three-dimensional, parametric, finite element models based on brick elements are applied to describe the mechanical behaviour of the structure for a wide range of relevant geometrical parameters. The results of the serial finite element analyses are approximated analytically and thus can be offered to potential users to determine the stresses at arbitrary points of the nozzle-to-vessel junction and to predict the most probable location of fatigue failure. (C) 1998 Elsevier Science Ltd. All rights reserved.