Plastic Collapse Assessment of Thick Vessels Under Internal Pressure According to Various Hardening Rules

2010 ◽  
Vol 132 (5) ◽  
Author(s):  
A. Chaaba
Keyword(s):  
Internal Pressure ◽  
Strain Hardening ◽  
Limit Analysis ◽  
Limit State ◽  
Plastic Behavior ◽  
Plastic Collapse ◽  
Perfectly Plastic ◽  
Von Mises ◽  
Hardening Rules ◽  
Collapse Assessment

This paper aims to deal with plastic collapse assessment for thick vessels under internal pressure, thick tubes in plane strain conditions, and thick spheres, taking into consideration various strain hardening effects and large deformation aspect. In the framework of von Mises’ criterion, strain hardening manifestation is described by various rules such as isotropic and/or kinematic laws. To predict plastic collapse, sequential limit analysis, which is based on the upper bound formulation, is used. The sequential limit analysis consists in solving sequentially the problem of the plastic collapse, step by step. In the first sequence, the plastic collapse of the vessel corresponds to the classical limit state of the rigid perfectly plastic behavior. At the end of each sequence, the yield stress and/or back-stresses are updated with or without geometry updating via displacement velocity and strain rates. The updating of all these quantities (geometry and strain hardening variables) is adopted to conduct the next sequence. As a result of this proposal, we get the limit pressure evolution, which could cause the plastic collapse of the device for different levels of hardening and also hardening variables such as back-stresses with respect to the geometry change.

Plastic Collapse of Orthotropic Plates

1982 ◽  
Vol 26 (04) ◽  
pp. 286-295
Author(s):  
John C. Christodoulides ◽  
Joao G. de Oliveira
Keyword(s):  
Limit Analysis ◽  
Lateral Pressure ◽  
Yield Criterion ◽  
Plastic Collapse ◽  
Orthotropic Plates ◽  
Perfectly Plastic ◽  
Technical Theory ◽  
Orthotropic Shells ◽  
Theory Of Shells

A yield criterion for thin orthotropic shells expressed in terms of generalized stresses is first derived. This yield criterion is based on the yield criterion proposed by Hill for anisotropic continua and it is consistent with all the assumptions usually adopted in the technical theory of shells. As an example of application of this criterion the collapse of perfectly plastic rectangular orthotropic plates subjected to a uniform lateral pressure is studied using the Theorems of Limit Analysis.

Rigid-Plastic Collapse of Cylindrical Shells

1973 ◽  
Vol 95 (1) ◽  
pp. 215-218 ◽  
Author(s):  
H. M. Haydl ◽  
A. N. Sherbourne
Keyword(s):  
Limit Analysis ◽  
Cylindrical Shells ◽  
Numerical Approach ◽  
External Pressure ◽  
Plastic Collapse ◽  
Rigid Plastic ◽  
Limit Loads ◽  
Complex Problems ◽  
Safe Side ◽  
Von Mises

This paper suggests a simple numerical approach to the limit analysis of cantilever cylindrical shells. The loads considered are external pressure and external pressure combined with a moment at the free shell end. It is shown that the collapse loads are within 4.5 percent on the safe side of the exact von Mises limit loads. The extension of the method of analysis to more complex problems is suggested.

Plastic Collapse Assessment Procedure in P-M Diagram Method for Pipe Bends With a Local Thin Area Under Combined Pressure and Out-of-Plane Bending Moment

2012 ◽  
Author(s):  
Kenji Oyamada ◽  
Shinji Konosu ◽  
Takashi Ohno
Keyword(s):  
Internal Pressure ◽  
Pressure Ratio ◽  
Bending Moment ◽  
Piping System ◽  
Assessment Procedure ◽  
Plastic Collapse ◽  
Diagram Method ◽  
Out Of Plane ◽  
Plane Bending ◽  
Collapse Assessment

Pipe bends are common elements in piping system such as power or process piping, and local thinning are typically occurred on pipe bends due to erosion or corrosion. Therefore, it is important to establish the plastic collapse condition for pipe bends having a local thin area (LTA) under combined internal pressure and external bending moment. In this paper, a simplified plastic collapse assessment procedure in p-M (internal pressure ratio and external bending moment ratio) diagram method for pipe bends with a local thin area simultaneously subjected to internal pressure, p, and external out-of-plane bending moment, M, due to earthquake, etc., is proposed, which is derived from the reference stress. In this paper, only cases of that an LTA is located in the crown of pipe bends are considered. The plastic collapse loads derived from the p-M diagram method are compared with the results of both experiments and FEA for pipe bends of the same size with various configurations of an LTA.

Plastic Limit Loads for Through-Wall Cracked Pipes Using Finite Element Limit Analysis

2006 ◽  
Vol 321-323 ◽  
pp. 724-728
Author(s):  
Nam Su Huh ◽  
Yoon Suk Chang ◽  
Young Jin Kim
Keyword(s):  
Finite Element ◽  
Limit Analysis ◽  
Structural Integrity ◽  
Three Dimensional ◽  
Limit Load ◽  
Plastic Behavior ◽  
Plastic Limit ◽  
Integrity Assessment ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic

The present paper provides plastic limit load solutions for axial and circumferential through-wall cracked pipes based on detailed three-dimensional (3-D) finite element (FE) limit analysis using elastic-perfectly plastic behavior. As a loading condition, both single and combined loadings are considered. Being based on detailed 3-D FE limit analysis, the present solutions are believed to be valuable information for structural integrity assessment of cracked pipes.

Procedure for Plastic Collapse Assessment of a Local Thin Area Near Vessel and Nozzle Intersections Subjected to Internal Pressure and External Loadings

2015 ◽  
Author(s):  
Shinji Konosu ◽  
Kenta Ogasawara ◽  
Kenji Oyamada
Keyword(s):  
Internal Pressure ◽  
Critical Region ◽  
Pressure Ratio ◽  
Branch Pipe ◽  
Bending Moment ◽  
Plastic Collapse ◽  
Element Analysis ◽  
Diagram Method ◽  
External Moment ◽  
Collapse Assessment

This paper develops a procedure for plastic collapse assessment of vessel (run pipe) - nozzle (branch pipe) intersections with an arbitrarily positioned local thin area (LTA) under different loading conditions, namely internal pressure, external moment on a nozzle applied along various directions with respect to the vessel main axis, and pure bending moment on a vessel. Although simplified procedures for plastic collapse assessment based on the p-M (internal pressure ratio and external bending moment ratio) diagram method have been previously proposed for straight cylindrical vessels and pipe bends with an LTA, very few studies have dealt with the determination of plastic collapse load for an LTA in the critical region of intersecting vessels subjected to internal pressure and external moment loading. This is likely due to the complexity of the stresses caused by the applied loads in the critical region, which arises from geometric discontinuities. In this paper, simple and empirical formulae for predicting conservative plastic collapse loads for an LTA in the critical region of the intersecting vessels are proposed based on the analytical results of stresses at defect-free vessel-nozzle intersections by using linear finite element analysis (FEA). Localized elastic stress retardation factors are taken into account in the evaluation by the results of a non-linear FEA. Consequently, a p-M diagram method is developed for application to vessel-nozzle intersections with an LTA.

Using Limit Analysis for Seismic Evaluation of Component Located in Nuclear Power Plants

2002 ◽  
Author(s):  
Petr Zeman
Keyword(s):  
Limit Analysis ◽  
Nuclear Power ◽  
Power Plants ◽  
Evaluation Method ◽  
Static Load ◽  
Seismic Load ◽  
Plastic Behavior ◽  
Seismic Evaluation ◽  
Perfectly Plastic ◽  
American Society

Using limit analysis for evaluation of the seismic resistance of the components located in NPPs is compared with the standard evaluation method. This comparison is based on the procedure specified in American Society of Mechanical Engineers Boiler and Pressure Vessel Code, Section III. Subsection NC, version 1992 standard. The limit analysis uses perfectly plastic behavior of the material. The seismic load is restricted when using limit analysis to the pseudo-static load. The possibility of building of more realistic non-linear model including contacts is another advantage of limit analysis. Using limit analysis is the way to move the evaluation method closer to the real collapse load and to reduce conservatism.

Strain-Hardening Topography of Elastic-Plastic Materials

1983 ◽  
Vol 50 (4a) ◽  
pp. 795-801 ◽  
Author(s):  
J. Casey ◽  
H. H. Lin
Keyword(s):  
Strain Hardening ◽  
Type Theory ◽  
Plastic Behavior ◽  
Hardening Behavior ◽  
Perfectly Plastic ◽  
Plastic Materials ◽  
Different Types ◽  
Elastic Plastic Materials ◽  
Strain Hardening Behavior ◽  
Rate Type

In the context of a purely mechanical rate-type theory of plasticity, a special set of constitutive equations is discussed. A method [1,2] of characterizing strain-hardening behavior is utilized to examine the different types of response that may be exhibited. Loci of constant strain-hardening behavior in stress space and regions of hardening, softening, and perfectly plastic behavior are determined.

Studies on Plastic Flow of Anisotropic Metals

1956 ◽  
Vol 23 (3) ◽  
pp. 444-450
Author(s):  
L. W. Hu
Keyword(s):  
Stress Distribution ◽  
Internal Pressure ◽  
Strain Hardening ◽  
Plane Strain ◽  
Plastic Flow ◽  
Plane Stress ◽  
Biaxial Tension ◽  
Plastic Behavior ◽  
Theory Of Plastic Flow ◽  
Walled Cylinder

Abstract This investigation deals with a study of the plastic behavior of anisotropic metals. By extending Hill’s theory of plastic flow of anisotropic metals, plastic stress-strain relations for anisotropic materials with strain hardening are developed. Applications of these relations are also made to plane-stress and plane-strain problems with anisotropy. The effect of anisotropy on the stress distribution and on the pressure to produce yielding in a thick-walled cylinder under internal pressure is discussed. The influence of anisotropy on the interpretation of conventional biaxial tension-tension and tension-torsion tests is also considered in this study.

Validity of Procedure for Plastic Collapse Assessment of a Local Thin Area Near Vessel and Nozzle Intersections Subjected to Internal Pressure and External Loadings

2015 ◽  
Author(s):  
Kenji Oyamada ◽  
Shinji Konosu ◽  
Tetsuji Miyashita ◽  
Takashi Ohno ◽  
Hideyuki Suzuki
Keyword(s):  
Numerical Analysis ◽  
Internal Pressure ◽  
Branch Pipe ◽  
Plastic Collapse ◽  
Collapse Assessment

There are numerous cases in which a volumetric flaw such as a local thin area (LTA) is found in pressure equipment such as vessels, piping, tanks, and so on. Sometimes it is found near vessel and nozzle intersection. A fitness for service (FFS) rule of such cases was desired, because plastic collapse assessment of LTA near vessel and nozzle intersection usually needed to conduct by numerical analysis such as FEA. Recently, an FFS assessment rule of plastic collapse assessment of LTA near vessel (run-pipe) and nozzle (branch pipe) intersection subjected to internal pressure and external loadings has been developed and proposed by one of authors of this paper. In this paper, the proposed plastic collapse assessment rule was verified with results of experiments and FEA for cylindrical vessels with an LTA near vessel and nozzle intersections subjected to internal pressure and external loadings.

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