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Modeling fatique behavior of dents in petroleum pipelines
| dc.creator | Hoffmann, Roger Lynn | |
| dc.date.accessioned | 2012-06-07T22:49:00Z | |
| dc.date.available | 2012-06-07T22:49:00Z | |
| dc.date.created | 1997 | |
| dc.date.issued | 1997 | |
| dc.identifier.uri | https://hdl.handle.net/1969.1/ETD-TAMU-1997-THESIS-H643 | |
| dc.description | Due to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to digital@library.tamu.edu, referencing the URI of the item. | en |
| dc.description | Includes bibliographical references. | en |
| dc.description | Issued also on microfiche from Lange Micrographics. | en |
| dc.description.abstract | Dents in pipelines can seriously reduce the design life of a pipeline. Dents cause stress concentrations to develop which make dents susceptible to fatigue failures. Acceptance criteria of dents are currently only based on dent depth. To understand the behavior of dents in pipelines, a finite element parametric study was performed. Three dimensional shell element models were given elasto-plastic behavior for modeling dents in pipelines. Parameters modeled include dent depth, dent type, dent restraint, pipe diameter, thickness, grade, longitudinal stress, pipe support, and pressure at indentation. For the given parameters, the rebound behavior and stress behavior of dents were investigated. The displacement data were studied to understand the rebound characteristics of dents. Stress data were studied to determine failure modes of different combinations of dents and pipes. Dents reduce in size, or rebound, with removal of the force at indentation and pressurization. The amount of rebound is influenced by several parameters such as dent type and pipe wall thickness. Larger dents in terms of surface area of the dented region experience more rebound than smaller dents. Thinner pipes experience more rebound than thicker pipes. From the finite element modeling, the rebound characteristics can be predicted for a broad range of values for the various parameters. The study of the distribution of stresses in dented regions shows locations of possible fatigue failures. Two different modes of failure were found to exist. Longer dents in terms of dent length are susceptible to fatigue failures in the contact region of the dent. Shorter dents are not susceptible to failures in the contact region, but can have failures away from the contact region in the dent periphery. Shorter dents have higher fatigue lives as compared to longer dents. The mode of failure of a dent is influenced by a variety of parameters. The influence of various parameters of the fatigue strength of dents is studied using rebound and stress behavior to develop better acceptance criteria of dents to improve the reliability of dents in pipelines. | en |
| dc.format.medium | electronic | en |
| dc.format.mimetype | application/pdf | |
| dc.language.iso | en_US | |
| dc.publisher | Texas A&M University | |
| dc.rights | This thesis was part of a retrospective digitization project authorized by the Texas A&M University Libraries in 2008. Copyright remains vested with the author(s). It is the user's responsibility to secure permission from the copyright holder(s) for re-use of the work beyond the provision of Fair Use. | en |
| dc.subject | civil engineering. | en |
| dc.subject | Major civil engineering. | en |
| dc.title | Modeling fatique behavior of dents in petroleum pipelines | en |
| dc.type | Thesis | en |
| thesis.degree.discipline | civil engineering | en |
| thesis.degree.name | M.S. | en |
| thesis.degree.level | Masters | en |
| dc.type.genre | thesis | en |
| dc.type.material | text | en |
| dc.format.digitalOrigin | reformatted digital | en |
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