Numerical Investigation of Pressure-Cycling-Induced Fatigue Failure of Wrinkled Energy Pipelines

Wrinkle defects can be complex pipeline deformities to assess and can present the potential to initiate a pipeline release incident as a result of fatigue failure due to pressure cycling, if not dealt with accordingly. Specifically, the stress distribution arising due to applied loads such as internal pressure can vary rapidly due to the complex shape along the wrinkle profile, which may introduce complexities in subsequent assessments such as fatigue life analysis. This paper presents a methodology using numerical simulation for evaluating stress concentration factors of wrinkle defects of varying geometries. A nonlinear finite element model is developed to evaluate stress concentration factors induced by wrinkle defects within steel pipelines subjected to internal pressure. Afterward, data from full-scale laboratory tests for the wrinkled pipe specimens subjected to cyclic pressure fatigue loading are analyzed to evaluate stress concentration factors for comparable wrinkle profiles. Lastly, a comparison between the results of the stress concentration factors evaluated using the finite element method and test data is provided, followed by a brief discussion of potential sources of discrepancies between results obtained from these methods.