The stress variations which occur in indented pipes, due to internal pressure fluctuations, are investigated using the results of finite element (FE) analyses for two typical pipe steel materials. The insertion, and subsequent withdrawal, of an indenter results in residual stress and indentation. It is found that the stress variations in indented pipes, due to the internal pressure fluctuations, are in the elastic range for practical pressures. Semi-empirical formulations for predicting the stress variations and the indentation depth changes due to internal pressure fluctuations are developed. A very close correlation is obtained between the results obtained from the FE analyses and predictions based on semi-empirical formulations.
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