Simplified prediction of the creep buckling of cylinders under external pressure. Part 2: Experimental verification

1999 ◽  
Vol 18 (6) ◽  
pp. 1045-1059 ◽  
Author(s):  
A. Combescure
Keyword(s):  
Experimental Verification ◽  
External Pressure ◽  
Creep Buckling ◽  
Pressure Part

Bemessung von beulgefährdeten Druckschachtpanzerungen unter Außendruck – Teil 1: Unversteifte Stahlrohre/Buckling design of steel liners under external pressure – part 1: unstiffened steel pipes

Bauingenieur ◽  
2019 ◽  
Vol 94 (10) ◽  
pp. 366-377
Author(s):  
Harald Unterweger ◽  
Alexander Ecker
Keyword(s):  
External Pressure ◽  
Steel Pipes ◽  
Pressure Part

Zusammenfassung Bei der statisch konstruktiven Auslegung der stählernen Druckschachtpanzerungen von Triebwasserwegen wird mitunter nicht die Innendruckbelastung maßgebend, sondern die Außendruckbelastung infolge Bergwasserdruck. Dieser führt im Revisionsfall bei entleerter Druckrohrleitung zu einer hohen Beulgefährdung, bedingt durch die ausgeführten großen Rohrschlankheiten. Die Bemessungsregeln in der Praxis basieren auf analytischen und empirischen Modellen, die im Wesentlichen bereits in den 1960er-Jahren entwickelt wurden. Dieser Beitrag fasst die Gesamtergebnisse eines Forschungsprojektes zusammen, dass das Ziel hatte durch nun verfügbare realitätsnahe numerische Modelle zusätzliche Effekte, wie verschiedene Imperfektionsformen, auftretende Längsdruckkräfte im Rohr infolge Reibschluss sowie die radiale Gebirgsnachgiebigkeit, mit zu berücksichtigen. Teil 1 beinhaltet die Ergebnisse für unversteifte Stahlrohre. Es werden einleitend die in der Praxis üblichen Bemessungsmodelle zur Ermittlung der kritischen Außendruckbelastung p0,cr erläutert und hinsichtlich ihrer Ergebnisse miteinander verglichen. Aus dem zusätzlichen Vergleich mit den numerischen Berechnungsergebnissen wird das zutreffendste Bemessungsmodell für die Praxis dargestellt und auch in Form von Bemessungsdiagrammen aufbereitet.

Estimation of Creep Buckling Deformation Under External Pressure at Elevated Temperature

1996 ◽  
Vol 118 (2) ◽  
pp. 194-197 ◽  
Author(s):  
Y. Kaji ◽  
I. Ioka ◽  
I. Nishiguchi ◽  
Y. Miyamoto
Keyword(s):  
Heat Transfer ◽  
Elevated Temperature ◽  
External Pressure ◽  
Pressure Level ◽  
Collapse Time ◽  
Transfer Tube ◽  
Simplified Method ◽  
Creep Buckling ◽  
Leak Tightness ◽  
Pass Through

The effect of the initial ovality, wall thickness, and pressure level on the collapse time of a heat transfer tube subjected to both constant and cycled external pressure at elevated temperature was examined experimentally and analytically. The creep deformation of the tube obtained by FEM code and the simplified method was a good approximation. The simplified method proposed by Nishiguchi et al. is an effectual method in the estimation of the creep buckling deformation and the collapse time of the tube under external pressure at elevated temperature as compared with the experimental results and the FEM. Though many cracks initiated by creep collapse were observed on the outer surface of a few test tubes, the cracks did not pass through the tube thickness, and leak tightness was maintained despite a collapse for all tubes tested.

A Creep Buckling Design Method of Elliptical Heads Based on the External Pressure Chart

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Fang Liu ◽  
Jian-Guo Gong ◽  
Fu-Hai Gao ◽  
Fu-Zhen Xuan
Keyword(s):  
Design Method ◽  
External Pressure ◽  
Design Approach ◽  
Design Criteria ◽  
Design Factor ◽  
Simplified Method ◽  
Creep Buckling ◽  
Conservative Result

The buckling design criteria of elliptical heads in ASME VIII-1, ASME NH, and RCC-MRx are reviewed and compared. Accordingly, an external pressure chart (EPC) based buckling design approach is developed for elliptical heads in the creep range. Results indicate that for instantaneous buckling design, RCC-MRx predicts higher allowable pressure compared with ASME NH, which is ascribed to the smaller design factor. The proposed method produces a similar result with that given by ASME VIII-1. By contrast, the proposed method leads to a reasonably conservative result with the factor n of 0.03 for the creep buckling design. While the simplified method in RCC-MRx provides an over-conservative solution.

Creep Buckling and Post Buckling Behaviors of Stainless Steel Tube Columns Under External Pressure at Extremely High Temperatures

2016 ◽  
Author(s):  
Byeongnam Jo ◽  
Koji Okamoto ◽  
Naoto Kasahara
Keyword(s):  
Stainless Steel ◽  
Failure Time ◽  
External Pressure ◽  
Steel Tube ◽  
Stainless Steel Tube ◽  
Creep Tests ◽  
Additional Heating ◽  
Creep Buckling ◽  
Post Buckling ◽  
Buckling Failure

Creep buckling failure of a stainless steel tube column was investigated at three temperature conditions (800, 900, and 1000 °C). 304 grade stainless steel was used as a test material in this study. In creep tests, external pressure was increased to a target value, temperature of the tube column was quickly increased to a target temperature, and failure time was measured maintaining the pressure and the temperature. Based on the experimental results of the creep buckling failure time, an empirical correlation was developed by the Larson-Miller parameter. Moreover, post buckling experiments were performed to examine buckling-induced boundary failure at extremely high temperature more than 1300 °C. Additional heating was applied to the specimen which already buckled by external pressure. In the additional heating tests, temperature was increased until boundary failure was formed on the surface of the tube columns. The results showed that the creep buckling failure time was shorter than those in other tensile stress-induced creep tests. The empirical correlation obtained by Larson-Miller parameter predicts well the creep buckling failure time. Finally, boundary failure was obtained in the post buckling under the additional heating.

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