New Criterion for the Definition of Plastic Limit Load in Nozzle Connections of Pressure Vessels

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
V. N. Skopinsky ◽  
N. A. Berkov
Keyword(s):  
Numerical Procedure ◽  
Limit Load ◽  
Local Deformation ◽  
Experimental Models ◽  
Pressure Vessels ◽  
Plastic Work ◽  
Plastic Limit ◽  
Element Analysis ◽  
Plastic Limit Load ◽  
New Criterion

In this research, a new criterion for determining the plastic limit load in shell intersections using elastic-plastic finite element analysis is presented. Using the proposed maximum criterion of the rate of the change of the relative plastic work (PW), a numerical procedure is described to define the plastic pressure. Also, a specific plastic work criterion is presented using a local deformation parameter. Results of comparisons with different criteria were considered for experimental models of cylindrical vessels with radial and nonradial (lateral) nozzles. A parametric study of the radial intersections of cylindrical shells under the internal pressure loading was performed to examine the influence of the diameter ratio on the plastic limit pressure on the basis of the proposed criteria.

Determination of Transition From Thin Shell to Thick Shell Theory for Torispherical Heads With Head Dish Radius to Thickness Ratios Under 20

2020 ◽  
Author(s):  
Barry Millet ◽  
Kaveh Ebrahimi
Keyword(s):  
Internal Pressure ◽  
Transition Point ◽  
Limit Load ◽  
Thick Wall ◽  
Ratio Test ◽  
Thin Wall ◽  
Plastic Limit ◽  
Element Analysis ◽  
Perfectly Plastic ◽  
Plastic Limit Load

Abstract This paper will clarify the point of transition where the behavior of the dish of a torispherical head goes from thin wall theory (collapse failure and membrane) to thick wall (burst failure) as the head dish radius to thickness ratios (L/t) gets smaller. There are several stated ratio limits for this transition. Three separate Welding Research Bulletins WRC 364 New Design Curves for Torispherical Heads[1], WRC 444 Buckling Criteria for Torispherical Heads Under Internal Pressure [3] and, WRC 501 Design of Torispherical and Ellipsoidal Heads Subjected to Internal Pressure[4] each provide a different definition of the transition point, that being 16.67, 15 and 20 respectively. This paper will review the actual test performed for L/t ratios from 20 down to 15 (which is the lowest ratio test run) and provide the results of a numerical desktop study in lieu of actual testing. Linear elastic, elastic perfectly plastic limit load and elastic plastic limit load finite element analysis will be parametrically run across many L/t ratios and the knuckle radius will be varied across the runs. The results will be reviewed to check through wall behavior to find the transition point of thin to thick wall behavior. These will also be compared against the existing ASME BVP Section VIII Division 2 [5] formulas.

Plastic Limit Pressure of Pressurized Cylinders With Hillside Nozzle

2006 ◽  
Author(s):  
H. F. Wang ◽  
Z. F. Sang ◽  
L. P. Xue ◽  
G. E. O. Widera
Keyword(s):  
Finite Element ◽  
Limit Load ◽  
Experimental Models ◽  
Plastic Limit ◽  
Element Analysis ◽  
Design Guideline ◽  
Limit Pressure ◽  
Test Models ◽  
Scale Test ◽  
Plastic Limit Pressure

Cylinder-nozzle intersections are widely used in pressure vessel and piping industries. In order to get better mixing and energy exchange of the reactants, pipe-nozzle intersection with hillside nozzle is applied more and more widely. The purpose of this work is to investigate the plastic limit load of cylinders with hillside nozzle subjected to internal pressure. Three full-scale test models with different angles of the hillside nozzle were designed and fabricated specially for the test using strain gagues. 3-D finite element numerical simulations on the experimental models were performed. Based on both results, a group of basic data on plastic limit pressure defined by double elastic-slope method for cylinders with hillside nozzle is approximately obtained according to load-strain responses, and the plastic limit pressures determined by test and finite element analysis are in good agreement. The results indicate that the limit pressure increases with the increment of the angle of the hillside nozzle, and compared with radial nozzles in cylinders, the hillside nozzles have higher limit pressure, which can be served as the basis for developing a design guideline for pressurized cylinders with various angles of hillside nozzle.

Plastic Limit Load Analysis of Cylindrical Pressure Vessels with Different Nozzle Inclination

2015 ◽  
Vol 97 (2) ◽  
pp. 163-174
Author(s):  
Anupam Prakash ◽  
Harit Kishorchandra Raval ◽  
Anish Gandhi ◽  
Dipak Bapu Pawar
Keyword(s):  
Limit Load ◽  
Pressure Vessels ◽  
Plastic Limit ◽  
Plastic Limit Load ◽  
Load Analysis

Analysis and Experiments on the Plastic Limit Load of Elbows under Combined Pressure and In-Plane Closing Bending Moment

2013 ◽  
Vol 774-776 ◽  
pp. 1090-1097 ◽  
Author(s):  
Zhi Xiang Duan ◽  
Kun Shi
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Safety Assessment ◽  
Bending Moment ◽  
Limit Load ◽  
Experimental Results ◽  
Plastic Limit ◽  
Element Analysis ◽  
Limit Pressure ◽  
Plastic Limit Load

This paper discusses the plastic limit load of elbows without defects and with local thinned area (LTA) in the extrados under combined pressure and in-plane closing bending moment. Finite element analysis (FEA) and experiments have been used. The results of FEA show that, for the elbows without defects, when the ratio of pressure to the limit pressure (P/PL) is smaller than 0.469, the limit moment of elbows increases with the increasing pressure; when the ratio (P/PL) is bigger than 0.469, the limit moment of elbow decreases with the increasing pressure. For the elbows with LTA, the FEA results show that with different LTA the variation of the limit load of elbows to the pressure is different. Perhaps, the limit moment of elbows always decreases with the increasing pressure. It is also likely that the limit moment of elbows increases with the increasing pressure and then decreases with the increasing pressure. The results of FEA are consistent with the experimental results. By fitting the results of FEA, the safety assessment figure for elbows under combined pressure and in-plane closing bending moment is drawn.

Plastic Analysis for Cylindrical Vessels Under In-Plane Moment on the Nozzle

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
B. H. Wu ◽  
Z. F. Sang ◽  
G. E. O. Widera
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Limit Load ◽  
Cylindrical Vessel ◽  
Plastic Limit ◽  
Element Analysis ◽  
Test Models ◽  
Scale Test ◽  
Plastic Limit Load

The objective of this paper is to determine the plastic limit moment for cylindrical vessels with a nozzle under in-plane moment loading. Three full scale test models with different d/D ratios were fabricated for the experiment. A three-dimensional nonlinear finite element analysis was also performed. The plastic limit moment of the cylindrical vessel-nozzle connections was determined approximately by the twice-elastic-slope criterion. The results indicate that the plastic limit moments obtained by the experiment and finite element analysis are in good agreement. On the basis of the above results, a parametric analysis of the plastic limit moment for cylindrical vessels under in-plane moment on the nozzle was carried out, and an empirical formula is proposed. The results can serve as a supplement to the available data of plastic limit load for cylindrical vessel-nozzle connection structures under external load.

A Study on the Effect of Non-Idealized Crack on a 90° Elbow by Using Finite Element Analysis

2018 ◽  
Author(s):  
Jae-Hee Kim ◽  
Min-Kyu Kim ◽  
Ye-Rin Choi ◽  
Doo-Ho Cho ◽  
Moon Ki Kim ◽  
...  
Keyword(s):  
Finite Element ◽  
Numerical Study ◽  
Limit Load ◽  
Element Model ◽  
Assessment Method ◽  
Accurate Solution ◽  
Fe Model ◽  
Plastic Limit ◽  
Element Analysis ◽  
Plastic Limit Load

The present paper proposed the modified limit load solution related to code case N-513-4 which is currently actively researched. To apply to assessment method for an elbow in code case N-513-4, the crack should be postulated as the idealized circumferential through-wall crack (TWC). For this reason, it could be led to overestimate the results due to the assumption of real crack shape. Then, the many research which is related to an accurate solution for a straight pipe by considering realistic crack has been investigated. However, the accurate solution for the elbow with non-idealized TWC is still lacked. Therefore, based on three-dimensional finite element model, the effect of non-idealized circumferential TWC on plastic limit load was investigated under internal pressure. To do this, the finite element (FE) model and analysis procedure employed in the present numerical study were validated by comparing the present finite element analyses result with existing solutions for idealized TWC in the elbow. Then, the correction factor for calculating plastic limit load was newly proposed as a tabulated form by considering practical ranges of geometry.

Use of Limit Load Analysis for Design of Pressure Vessel Cover

2012 ◽  
Author(s):  
Rahul Jain
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Pressure Vessel ◽  
Limit Load ◽  
Plastic Limit ◽  
Element Analysis ◽  
Linear Elastic ◽  
Reference Volume ◽  
Plastic Limit Load ◽  
Load Analysis

This paper explores the use of limit load analysis methods for the design of a pressure vessel manway cover as per the ASME boiler and pressure vessel code guidelines. The results of elastic and limit load finite element analysis are discussed for the design. The concept of reference volume consideration along with linear elastic finite element analysis to determine the lower bound limit load has been explored and the results are compared with the non-linear elastic-plastic limit load analysis.

Elastoplastic Solution and Limit Load Analysis of Orthotropic Cylindrical Shell Subjected to Internal Pressure

2019 ◽  
Author(s):  
Yujie Zhao ◽  
Min Xu ◽  
Chunxiao Li ◽  
Binbin Zhou ◽  
Xiaohua He ◽  
...  
Keyword(s):  
Cylindrical Shell ◽  
Shell Structure ◽  
Elastic Limit ◽  
Yield Criterion ◽  
Orthotropic Cylindrical Shell ◽  
Three Dimensional ◽  
Limit Load ◽  
Pressure Vessels ◽  
Plastic Limit ◽  
Plastic Limit Load

Abstract Cylindrical shell structure is widely used in pressure vessels. In this paper, the orthotropic cylindrical shell structure is analyzed based on the theory of elastoplastic mechanics and the Hill48 yield criterion, the elastoplastic limit load expression of the orthotropic cylindrical shell and the corresponding three-dimensional stress formulas at different stages are obtained. The effect of the radius ratio and the yield strength ratio on the elastic limit load and plastic limit load of the cylindrical shell are also discussed. Finally, the orthotropic cylindrical shell structure is simulated by finite element method, the numerical results verify the correctness of the analytical solutions.

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