Collapse of tubes with Lüders bands under bending

Simple item page
dc.contributor.advisorKyriades, Stelios
dc.creatorOk, Ali
dc.date.accessioned2017-07-14T14:18:17Z
dc.date.available2017-07-14T14:18:17Z
dc.date.issued2007-12
dc.description.abstractIn several practical applications hot-finished pipe that exhibits Lüders banding over part of its plastic deformation regime must be bent to strains of 2-3%. Lüders banding is a material instability associated with localized deformation. Bending induces ovalization to the tube that leads to a limit load instability and subsequently to collapse. For thinner walled pipes, the limit load is preceded by wrinkling that precipitates local kinking and collapse. This thesis uses experiments and numerical modeling to investigate how Lüders banding influences these modes of collapse. Carbon steel tubes with D/t ratios of 24.3 and 18.9 were heat-treated in order for the Lüders banding to develop. The tubes were then bent to failure under curvature control. The tubes tested exhibited moment plateaus associated with the development of inclined Lüders bands on the tension and compression sides of the tubes. Concurrently, bending was observed to localize over part of the tube, with the higher curvature zone gradually spreading over the whole length of the tube. Subsequently the lower D/t tubes exhibited a stable regime characterized by increasing moment and uniform curvature, which lead to a moment maximum and diffuse local ovalization. By contrast, tubes with D/ t = 24.2 did not exhibit a stable branch. The moment plateau terminated with the tube collapsing by localized diffuse ovalization. Tube bending was simulated using a finite element model in which the tube was assigned small initial geometric imperfections. The material behavior was modeled as elastic-plastic with an up-down-up stress-strain response over the range of the Lüders banding behavior. The model reproduced the major characteristics of the experiments. This includes the moment plateau, its extent, the coexistence of two curvature regimes, and the subsequent return to uniform deformation followed by collapse. A parametric study conducted with the model developed showed that the interaction of structural instabilities with Lüders banding depends of the tube D/t.en_US
dc.description.departmentMechanical Engineeringen_US
dc.format.mediumelectronicen_US
dc.identifierdoi:10.15781/T2PK07G85
dc.identifier.urihttp://hdl.handle.net/2152/60428
dc.language.isoengen_US
dc.relation.ispartofUT Electronic Theses and Dissertationsen_US
dc.rightsCopyright © is held by the author. Presentation of this material on the Libraries' web site by University Libraries, The University of Texas at Austin was made possible under a limited license grant from the author who has retained all copyrights in the works.en_US
dc.rights.restrictionRestricteden_US
dc.subjectLuders bandingen_US
dc.subjectTube collapseen_US
dc.subjectBendingen_US
dc.titleCollapse of tubes with Lüders bands under bendingen_US
dc.typeThesisen_US
dc.type.genreThesisen_US
thesis.degree.departmentMechanical Engineeringen_US
thesis.degree.disciplineMechanical Engineeringen_US
thesis.degree.grantorUniversity of Texas at Austinen_US
thesis.degree.levelMastersen_US
thesis.degree.nameMaster of Scienceen_US

Access full-text files

Original bundle

Now showing 1 - 1 of 1
No Thumbnail Available
Name:
txu-oclc-212928450.pdf
Size:
3.64 MB
Format:
Adobe Portable Document Format
Description:
Access restricted to UT Austin EID holders
Download

License bundle

Now showing 1 - 1 of 1
No Thumbnail Available
Name:
license.txt
Size:
1.66 KB
Format:
Item-specific license agreed upon to submission
Description:
Download

Collections

UT Electronic Theses and Dissertations