Elastic-Plastic Analysis of Some Pressure Vessel Heads

1970 ◽  
Vol 92 (2) ◽  
pp. 309-316 ◽  
Author(s):  
E. P. Popov ◽  
M. Khojasteh-Bakht ◽  
P. Sharifi
Keyword(s):  
Finite Element ◽  
Internal Pressure ◽  
Pressure Vessel ◽  
Good Accuracy ◽  
Yield Condition ◽  
Flow Rule ◽  
Elastic Plastic ◽  
Plastic Analysis ◽  
Thin Walled ◽  
Associated Flow Rule

Sixteen ASME standard torispherical heads attached to cylinders and subjected to internal pressure are analyzed as elastic and/or elastic-plastic shells using a new finite element. As basic elements, thin-walled frusta with curved meridians having common tangents and radii at the nodal circles are employed assuring good accuracy of the results. In the plastic analysis each wall-thickness was subdivided into concentric lamina in order to monitor the behavior of the material. The incremental law of plasticity in conjunction with the Mises yield condition and the associated flow rule were used in the inelastic range. The results of the analysis are presented in detail and are compared with the provisions of the ASME Pressure Vessel Code.

Elastic-Plastic Stress Analysis of Pressure Vessels

2012 ◽  
Author(s):  
Yang-chun Deng ◽  
Gang Chen
Keyword(s):  
Internal Pressure ◽  
Stress Analysis ◽  
Strain Hardening ◽  
Pressure Vessel ◽  
Plastic Instability ◽  
Pressure Vessels ◽  
Structural Deformation ◽  
Elastic Plastic ◽  
Thin Walled ◽  
Plastic Stress

To save material, the safety factor of pressure vessel design standards is gradually decreased from 5.0 to 2.4 in ASME Boiler and Pressure Vessel Codes. So the design methods of pressure vessel should be more rationalized. Considering effects of material strain hardening and non-linear structural deformation, the elastic-plastic stress analysis is the most suitable for pressure vessels design at present. This paper is based on elastic-plastic theory and considers material strain hardening and structural deformation effects. Elastic-plastic stress analyses of pressure vessels are summarized. Firstly, expressions of load and structural deformation relationship were introduced for thin-walled cylindrical and spherical vessels under internal pressure. Secondly, the plastic instability for thin-walled cylindrical and spherical vessels under internal pressure were analysed. Thirdly, to prevent pressure vessels from local failure, the ductile fracture strain of materials was discussed.

A Simplified Technique for Shakedown Load Determination of a 90 Degree Pipe Bend Subjected to Constant Internal Pressure and Cyclic In-Plane Bending

2005 ◽  
Author(s):  
Hany F. Abdalla ◽  
Maher Y. A. Younan ◽  
Mohammed M. Megahed
Keyword(s):  
Finite Element ◽  
Cyclic Loading ◽  
Internal Pressure ◽  
High Heat ◽  
Heat Fluxes ◽  
Elastic Analysis ◽  
Pipe Bend ◽  
Elastic Plastic ◽  
Plastic Analysis ◽  
Plane Bending

In this paper a simple technique is presented to determine the shakedown load of a 90 degree pipe bend subjected to constant internal pressure and cyclic in-plane bending using the finite element method. Through the proposed technique, the shakedown load is determined without performing time consuming cyclic loading simulations or conventional iterative elastic techniques. Instead, the shakedown load is determined through performing only two analyses namely; an elastic analysis and an elastic-plastic analysis. By extracting the results of the two analyses, the shakedown load is determined through the calculation of the residual stresses developed in the pipe bend. In the elastic analysis, performed only once and stored, an in-plane closing moment is applied preserving structure stresses within the material elastic range. In the elastic-plastic analysis, a constant internal pressure, below the pressure to cause yielding, is applied in addition to an increasing moment magnitude that causes the material yield strength to be exceeded. For verification purposes, the results of the simplified technique are compared to the results of full cyclic loading finite element simulations where the pipe bend is subjected to constant internal pressure and cyclic in-plane closing moment loading. In order to have confidence in the proposed technique, it is applied beforehand on the Bree cylinder [1] subjected to constant internal pressure and cyclic high heat fluxes across its wall. The results of the proposed technique showed very good correlation with the, analytically determined, Bree diagram of the cylinder.

Tresca’s Yield Condition and the Rotating Disk

1983 ◽  
Vol 50 (3) ◽  
pp. 676-678 ◽  
Author(s):  
U. Gamer
Keyword(s):  
Stress Field ◽  
Plastic Strain ◽  
Tensile Stress ◽  
Displacement Field ◽  
Yield Condition ◽  
Rotating Disk ◽  
Flow Rule ◽  
Elastic Plastic ◽  
Solid Disk ◽  
Associated Flow Rule

The displacement field belonging to the elastic-plastic stress field in a rotating solid disk that can be found with the help of Tresca’s yield condition, in textbooks on plasticity, is discontinuous at the elastic-plastic interface. Tresca’s yield condition cannot be applied to this problem since its associated flow rule predicts a negative plastic strain caused by a tensile stress.

First and Second Order Elastoplastic Analyses of Thin-Walled Metal Members using Generalized Beam Theory

2018 ◽  
Author(s):  
Miguel Abambres
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Cross Section ◽  
Beam Theory ◽  
Second Order ◽  
Flow Rule ◽  
Non Linear ◽  
Thin Walled ◽  
Shell Finite Element ◽  
Generalized Beam Theory

Original Generalized Beam Theory (GBT) formulations for elastoplastic first and second order (postbuckling) analyses of thin-walled members are proposed, based on the J2 theory with associated flow rule, and valid for (i) arbitrary residual stress and geometric imperfection distributions, (ii) non-linear isotropic materials (e.g., carbon/stainless steel), and (iii) arbitrary deformation patterns (e.g., global, local, distortional, shear). The cross-section analysis is based on the formulation by Silva (2013), but adopts five types of nodal degrees of freedom (d.o.f.) – one of them (warping rotation) is an innovation of present work and allows the use of cubic polynomials (instead of linear functions) to approximate the warping profiles in each sub-plate. The formulations are validated by presenting various illustrative examples involving beams and columns characterized by several cross-section types (open, closed, (un) branched), materials (bi-linear or non-linear – e.g., stainless steel) and boundary conditions. The GBT results (equilibrium paths, stress/displacement distributions and collapse mechanisms) are validated by comparison with those obtained from shell finite element analyses. It is observed that the results are globally very similar with only 9% and 21% (1st and 2nd order) of the d.o.f. numbers required by the shell finite element models. Moreover, the GBT unique modal nature is highlighted by means of modal participation diagrams and amplitude functions, as well as analyses based on different deformation mode sets, providing an in-depth insight on the member behavioural mechanics in both elastic and inelastic regimes.

Elastic and elastic-plastic finite element analysis of hollow tubes with axisymmetric internal projections under combined axial and pressure loading

2001 ◽  
Vol 36 (4) ◽  
pp. 373-390 ◽  
Author(s):  
S. J Hardy ◽  
M. K Pipelzadeh ◽  
A. R Gowhari-Anaraki
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Plastic Material ◽  
Axial Loading ◽  
Material Model ◽  
Pressure Loading ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Applied Loading

This paper discusses the behaviour of hollow tubes with axisymmetric internal projections subjected to combined axial and internal pressure loading. Predictions from an extensive elastic and elastic-plastic finite element analysis are presented for a typical geometry and a range of loading combinations, using a simplified bilinear elastic-perfectly plastic material model. The axial loading case, previously analysed, is extended to cover the additional effect of internal pressure. All the predicted stress and strain data are found to depend on the applied loading conditions. The results are normalized with respect to material properties and can therefore be applied to geometrically similar components made from other materials, which can be represented by the same material models.

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