Determination of Optimal Flat-End Head Geometries for Pressure Vessels Based on Numerical and Experimental Approaches

The experimental and numerical analyses of the pressure vessels with different flat ends are presented and discussed in the paper. The main aim of the study is to propose the optimal flat head end geometry. The analyses are focused on the comparison of standardized geometries and with the proposed elliptical cut-out. The experimental tests with the application of strain-gauge measurements and numerical modeling of the pressure vessel are conducted. The behavior under low and high pressures and the influence of the residual welding stresses, material properties, and geometrical tolerances on the level of the plastic deformation in the flat end is discussed. It is presented that the rules given in the recent standard are not sufficient for optimal selection of the optimal geometry. It is observed that in certain geometries the deviations of the pipe thickness may lead to a significant increase of the equivalent stresses. The residual welding stresses have a significant influence on the stress and strain level—particularly in the stress relief groove (SRG). The performed study and comparison of the different geometries allow for the proposal of the optimal shape of the flat end. It appeared that the pressure vessels with SRG are the most optimal choice, particularly when elliptic shapes are in use. In some cases (i.e., pipe with wall-thickness equal to 40 mm and the flat end with circular SRG), the optimal configuration is reached for dimensions beyond the admissible by code range.

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Design of Flat Ends in Pressure Boilers with Circular and Elliptical Stress Relieve Grooves

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.477-478.49 ◽

2013 ◽

Vol 477-478 ◽

pp. 49-53 ◽

Cited By ~ 2

Author(s):

Bogdan Szybiński

Keyword(s):

Numerical Analysis ◽

Stress Concentration ◽

Circumferential Stress ◽

Stress Relief ◽

Pressure Vessels ◽

Optimal Choice ◽

Circular Shape ◽

Relief Groove ◽

Two Parameters

Flat ends in cylindrical pressure vessels are a certain alternative for commonly used in boilers dished ends. These ends can have different form and one of the admitted proposals is the plate with the internally introduced circumferential stress relief groove. In codes [1, the grooves of circular shape are recommended. Three parameters describe the groove configuration, namely the groove radius, the minimum endplate thickness under the relief groove and the chamfer angle. The respective formulas for calculations of the first two parameters are expressed in the form of inequalities. This means that a certain range of their variation is possible. The existing codes do not give the clear suggestion about the optimal choice of values of the groove parameters, leading to the minimal value of the stress concentration in the groove area. This is usually done by numerical analysis. The significant reduction of stress concentration is observed when changing the shape of the groove from the circular to the elliptical one, which is also shown in the paper.

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Selection of insulation-sewing materials for rooms of class «R» floating restaurant by the method of multi- criteria comparison of alternative options

Russian Journal of Water Transport ◽

10.37890/jwt.vi63.81 ◽

2020 ◽

pp. 103-108

Author(s):

Anastasia A. Stepanova ◽

Tatyana A. Mikheeva

Keyword(s):

Comparison Method ◽

Optimal Choice ◽

Quality Level ◽

Insulation Material ◽

Interior Decoration ◽

Insulating Materials ◽

Insulation Materials ◽

Technological Level ◽

Selection Of

This article proposes and considers a method for solving the problem of the optimal choice of insulation and sewing materials for the interior of a floating class «P» restaurant. This method is based on the principle of multi-criteria comparison of alternative options [1]. For comparison, most suitable insulation materials for a vessel of this type were selected. Since in modern shipbuilding safety and comfort demands of the interior of the vessels are high, so the requirements for insulation materials on the interior are also high. Various characteristics of insulating and sewing materials, which determine their quality level, were analyzed in details. When studying the characteristics of insulating materials, the technological level and competitiveness of the manufacturer were taken into account. To determine the most suitable insulation material for the interior decoration of the floating restaurant, multi-criteria comparison method was first applied. The determination of the materials competitiveness was made.

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Development of a Novel Integrated CCSD-ITARA-MARCOS Decision-Making Approach for Stackers Selection in a Logistics System

Mathematics ◽

10.3390/math8101672 ◽

2020 ◽

Vol 8 (10) ◽

pp. 1672 ◽

Cited By ~ 1

Author(s):

Alptekin Ulutaş ◽

Darjan Karabasevic ◽

Gabrijela Popovic ◽

Dragisa Stanujkic ◽

Phong Thanh Nguyen ◽

...

Keyword(s):

Decision Making ◽

Multiple Criteria Decision Making ◽

Integrated Approach ◽

Optimal Choice ◽

Illustrative Case ◽

Logistics System ◽

Illustrative Case Study ◽

Logistics Activity ◽

Selection Of

The main goal of this paper is to propose a Multiple-Criteria Decision-Making (MCDM) approach that will facilitate decision-making in the field of logistics—i.e., in the selection of the optimal equipment for performing a logistics activity. For defining the objective weights of the criteria, the correlation coefficient and the standard deviation (CCSD method) are applied. Furthermore, for determining the semi-objective weights of the considered criteria, the indifference threshold-based attribute ratio analysis method (ITARA) is used. In this way, by combining these two methods, the weights of the criteria are determined with a higher degree of reliability. For the final ranking of the alternatives, the measurement of alternatives and ranking according to the compromise solution method (MARCOS) is utilized. For demonstrating the applicability of the proposed approach, an illustrative case study pointing to the selection of the best manual stacker for a small warehouse is performed. The final results are compared with the ones obtained using the other proved MCDM methods that confirmed the reliability and stability of the proposed approach. The proposed integrated approach shows itself as a suitable technique for applying in the process of logistics equipment selection, because it defines the most influential criteria and the optimal choice with regard to all of them in a relatively easy and comprehensive way. Additionally, conceiving the determination of the criteria with the combination of objective and semi-objective methods enables defining the objective weights concerning the attitudes of the involved decision-makers, which finally leads to more reliable results.

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Optimization of Selected Parameters and Procedures in Small Punch Test Methodology

Volume 6: Materials and Fabrication ◽

10.1115/pvp2020-21024 ◽

2020 ◽

Author(s):

Radim Kopriva ◽

Petra Klatovska ◽

Katerina Rusnakova ◽

Petr Gal ◽

Ivana Eliasova ◽

...

Keyword(s):

Mechanical Properties ◽

Experimental Tests ◽

Structural Materials ◽

Pressure Vessels ◽

Experimental Program ◽

Small Punch Test ◽

Small Punch ◽

Punch Test ◽

Current State

Abstract Assessment of reactor pressure vessels and other industrial components structural materials properties is currently based on the principles of using standardized and long-term employed methods of mechanical properties testing (e.g. impact tests, tensile tests). For the assessment of the current state and degradation prediction of an operated component, implementation of structural materials tests is nonetheless very complicated in terms of the availability of the material volume required to realization of tests in accordance with current normative documentation requirements. Due to the problematic material sampling from the operated component without affecting its integrity, more and more attention is paid to the implementation of perspective methods of evaluation of mechanical properties in processes of industrial component safe operation evaluation. These methods are mainly based on a semi-destructive approach allowing direct sampling of small volumes of material from the operated component and subsequent determination of mechanical properties using miniaturized test specimens. One of the most widespread perspective methods is the small punch test (SPT) - method based on the controlled deformation of thin sheets. The subject of the paper is the optimization of selected small punch test parameters, preparation technology of testing specimens and determination of suitable geometry of experimental fixtures, that are used for experiments in the testing laboratories. Within the experimental program attention is especially paid to the comparison of receiving hole edge configuration - radius/chamfer edge. The aim of the paper is to solve several open questions in the current state of small punch testing methodology and to obtain a comprehensive basis for the implementation of resulting recommendations into the process of currently ongoing standardization within the normative organizations ASTM and EN. This is achieved through a program of experimental tests and computational analyses (FEM) on the IAEA correlation material A533B (JRQ).

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Optimization of Flat Ends in Pressure Vessels

Materials ◽

10.3390/ma12244194 ◽

2019 ◽

Vol 12 (24) ◽

pp. 4194 ◽

Cited By ~ 3

Author(s):

Bogdan Szybiński ◽

Paweł J. Romanowicz

Keyword(s):

Stress Concentration ◽

Parametric Optimization ◽

Stress Relief ◽

Pressure Vessels ◽

Optimal Choice ◽

Operating Pressure ◽

Plastic Properties ◽

Optimal Values ◽

Relief Groove ◽

Minimum Stress

The application of flat ends in pressure boilers is inevitably associated with the presence of stress concentration, which is observed in the vicinity of the junction of the cylinder and the closing flat plate. The analyzed flat end plates with stress relief grooves fall into the group of solutions recognized by the respective Standards of Calculations of Pressure Vessels. Unfortunately, no clear evidence is given in the Standards on how to choose the best groove parameters. This opens up the problem of the optimal choice of the groove parameters providing a minimum stress level. Even for the optimal values defining the stress relief groove geometry, certain plastic deformations are observed in the groove area for materials which exhibit elastic-plastic properties. Such a situation is completely unacceptable during exploitation, and a suitable reduction of the operating pressure is necessary. This paper discusses the effectiveness of other designs for flat ends used in pressure vessels. The proposed modifications took the form of external ribs applied around the top of the endplate circumference. The dimensions of these ribs were set using parametric optimization. The results of the study encouraged the authors to perform a more general analysis with the use of topology optimization. The results of all performed studies proved that the reduction of stress concentration and the full elimination of plastic deformation are possible. All numerical calculations were made using the finite element code (FEM), Ansys.

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Systematic procedure for the determination of the nature of the solutes prior to the selection of the mobile phase parameters for optimization of reversed-phase ion-pair chromatographic separations

Journal of Chromatography A ◽

10.1016/s0021-9673(01)84371-5 ◽

1989 ◽

Vol 478 (1) ◽

pp. 21-38 ◽

Cited By ~ 1

Author(s):

G Low

Keyword(s):

Mobile Phase ◽

Reversed Phase ◽

Ion Pair ◽

Chromatographic Separations ◽

Systematic Procedure ◽

Selection Of

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DETERMINING THE DESALINATION UNIT COMPOSITION FOR COSTAL AREAS AND SMALL ISLANDS USE ANALYTIC HIERARCHY PROCESS

Jurnal Rekayasa Lingkungan ◽

10.29122/jrl.v9i1.1986 ◽

2017 ◽

Vol 9 (1) ◽

Author(s):

Imam Setiadi ◽

Dinda Rita K. Hartaja

Keyword(s):

Analytic Hierarchy Process ◽

Energy Demand ◽

Pairwise Comparison ◽

Small Islands ◽

Ahp Method ◽

Analytic Hierarchy ◽

Comparison Research ◽

Hierarchy Process ◽

Selection Of

Selection of the appropriate composition desalination units can be done with a variety of method approaches, one of the method is the Analytic Hierarchy Process. In determining the desalination unit with AHP method to consider is setting a goal, an alternative criteria and pairwise comparison. Research for the determination of the exact composition of the desalination unit in order to achieve sustainable drinking water suppy in coastal areas and small islands has been conducted. The results of the study are as follows, the energy demand of 50.83%, operator costs of 26.64%, maintenance costs of 14.13% and chemical requirement 8.4%. For an alternative composition desalination unit of RO 10 m3 / day is the best alternative composition with value of 59.61%, the composition of the next alternative is RO 20 m3/ day of 30.40% and the last alternative of the desalination unit composition is RO 120 m3/ day of 09.99%.Key words : Desalination, Mukti Stage Flash Composition, AHP

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