Analysis of stresses in pipes indented by long external indentations and subsequent stress variations due to pressure fluctuations

The residual hoop stresses in pressurised pipes caused by long external indentations and the subsequent stress variations caused by internal pressure fluctuations are investigated for a range of residual indentation depths, support positions, pressure magnitudes and indenter radii, 7using the Finite Element (FE) method, including initial stress and geometrical non-linearity effects. Three materials are used in the investigation to assess the effects of material properties on the stress variations. A semi-empirical formulation is developed, based on an imperfect, indented pipe model and the results of the FE analyses, to predict the variations of the residual stresses in the pipes.