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.

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.

Design of Conical Shells Under External Loads

1980 ◽  
Vol 102 (2) ◽  
pp. 230-238 ◽  
Author(s):  
M. H. Jawad
Keyword(s):  
Experimental Data ◽  
Design Procedure ◽  
External Pressure ◽  
Moment Of Inertia ◽  
Design Criteria ◽  
Conical Shells ◽  
Division 1 ◽  
Simplified Method ◽  
Section Viii ◽  
External Loads

The background is presented for the rules for conical shells and reducers under external pressure which were recently added to Section VIII, Division 1. A simplified method for the design of conical shells under external pressure is developed from theoretical and experimental data. The design procedure is similar to that published by ASME for cylindrical shells. Design criteria for the conical-to-cylindrical junction is also established in terms of the minimum required area and moment of inertia at the junction.

Buckling Analysis in Creep Conditions: Review and Comparison

2002 ◽  
Author(s):  
Andre´ Turbat ◽  
Bernard Drubay
Keyword(s):  
High Temperature ◽  
Cylindrical Shells ◽  
External Pressure ◽  
Buckling Analysis ◽  
Buckling Load ◽  
Design Factor ◽  
Critical Loading ◽  
The Us ◽  
Creep Buckling ◽  
Creep Instability

In the case of structures operating at high temperature in normal or accidental conditions, the influence of creep has to be considered at the design stage because this phenomenon may reduce the lifetime significantly. This is true in particular for buckling analysis : in creep conditions, the buckling sometimes occurs after a long period under a compressive load which is lower than the critical load assessed when considering an instantaneous buckling. The main reason is that creep deformations induce an amplification of the initial geometrical imperfections and consequently a reduction of the buckling load. Some Design Codes incorporate special rules and/or methods to take creep buckling into account. Creep buckling analysis methods aim at evaluating critical loading for a given hold period with creep or alternatively critical creep time for a given loading. The Codes where creep buckling is considered also define margins with respect to critical loading : it shall be demonstrated that creep instability will not occur during the whole lifetime when multiplying the specified loading by a coefficient (design factor) depending on the situation level. For the design of NPP, specific creep buckling rules exist in the US, France and Russia. In the US, ASME, Section III, Subsection NH, which is dedicated to high temperature components design, provides limits which are applicable to general geometrical configurations and loading conditions that may cause buckling due to creep behaviour of the material. For load-controlled time-dependent creep buckling, the design factors to apply to the specified loadings are 1.5 for levels A, B or C service loadings and 1.25 for level D service loadings. A design factor is not required in the case of purely strain-controlled buckling. No specific method is provided to obtain critical loading or critical time for creep instability. In France, creep buckling rules included in RCC-MR, Chapter RB or RC 3200 are similar to those of ASME, Subsection NH. In addition, a new simplified method has been developed recently to assess critical creep loading/time for a shell under mechanical loading. Diagrams, presently valid for 316 austenitic steel, have been established from a ring model with perfect plasticity. Creep buckling load is determined applying a reduction factor to Euler instantaneous buckling load, depending on temperature, hold time, thinness of the structure and geometrical imperfection amplitude. This method has been validated by experimental tests and finite element results. It will be included in Appendix A7 of RCC-MR, Edition 2000. In Russia, the document PNAE G-7-002-86 applicable to NPP equipment and pipeline strength analysis, presents stability check analytical calculations to be performed to determine the allowable loading or allowable operation lifetime for typical geometries (cylindrical shells, dished ends) and loadings (external pressure, axial force). In the case of stability analysis under creep, creep deformation is assessed using a Norton law. In Germany, a KTA project including an analytical method for creep buckling analysis had also been proposed at the beginning of 90th to be used in HTR development. Finally, in India, a creep buckling analysis method has been proposed in the framework of PFBR project. As per this approach, elastic-plastic analysis should be performed replacing the instantaneous stress-strain curve at the design temperature by the isochronous curve for the time corresponding to the lifetime of the component and the same temperature. These methods are applied in the case of cylindrical shells under external pressure and comparative results are provided. The RCC-MR method appears to be reasonably conservative and applicable with several creep law types.

Factored axial compressive resistance of schifflerized angles

1991 ◽  
Vol 18 (6) ◽  
pp. 926-932 ◽  
Author(s):  
Seshu Madhava Rao Adluri ◽  
Murty K. S. Madugula
Keyword(s):  
Key Words ◽  
Design Method ◽  
Design Criteria ◽  
Design Practice ◽  
Buckling Mode ◽  
Flexural Buckling ◽  
Mode Of Failure ◽  
Current Design ◽  
Similarities And Differences ◽  
Compressive Resistance

The concept of schifflerization of 90° equal-leg angle is presented and its application in triangular-base latticed steel towers is explained. The similarities and differences between schifflerized angles and regular 90° angles are discussed. The current design practice for schifflerized angles is reviewed and its limitation is highlighted. A design method which includes the effect of the torsional-flexural buckling mode of failure is proposed. For ready use of designers, the factored axial compressive resistances of schifflerized angles are tabulated for both the present and proposed design methods. Key words: buckling, compressive resistance, design criteria, schifflerized angles, stability, standards, steel, struts, towers, guyed towers.

AN OPTIMIZATION MODEL FOR PRELIMINARY STABILITY AND CONFIGURATION ANALYSES OF SEMI-SUBMERSIBLES

2021 ◽  
Vol 159 (A3) ◽  
Author(s):  
G D Gosain ◽  
R Sharma ◽  
Tae-wan Kim
Keyword(s):  
Optimization Model ◽  
Design Method ◽  
Optimization Techniques ◽  
Design Approach ◽  
Preliminary Design ◽  
Design Environment ◽  
Preliminary Stage ◽  
Steel Weight ◽  
Motion Characteristics ◽  
Almost All

In the modern era of design governed by economics and efficiency, the preliminary design of a semi-submersible is critically important because in an evolutionary design environment new designs evolve from the basic preliminary designs and the basic dimensions and configurations affect almost all the parameters related to the economics and efficiency (e.g. hydrodynamic response, stability, deck load and structural steel weight of the structure, etc.). The present paper is focused on exploring an optimum design method that aims not only at optimum motion characteristics but also optimum stability, manufacturing and operational efficiency. Our proposed method determines the most preferable optimum principal dimensions of a semi-submersible that satisfies the desired requirements for motion performance and stability at the preliminary stage of design. Our proposed design approach interlinks the mathematical design model with the global optimization techniques and this paper presents the preliminary design approach, the mathematical model of optimization. Finally, a real world design example of a semi-submersible is presented to show the applicability and efficiency of the proposed design optimization model at the preliminary stage of design.

scholarly journals Fitness Center Design with Natural Shapes and Forms Approach in Surabaya

2021 ◽  
Vol 1 (1) ◽  
pp. 15-21
Author(s):  
Pande Putu Dwi Novigga Artha
Keyword(s):  
Psychological Health ◽  
Design Method ◽  
Design Criteria ◽  
Fitness Center ◽  
The People ◽  
Physical And Psychological Health ◽  
Special Approach ◽  
The City

Density of Surabaya city affects the physical and psychological health of the people. Productive activities accompanied by a dense environment mean that people rarely have time to exercise. To increase the awareness and interest of the people of the city of Surabaya to exercise, it is necessary to have a sports facility with a special approach. Biophilic theory, especially the natural shapes and form approach, can be a solution to these problems. The return of nature's essence into the building can provide positive benefits for human physical and physical health. Previous research has discussed the determination of fitness center design criteria with the natural shapes and forms approach in Surabaya. In this follow-up journal, we will discuss the final result or application of the design criteria into an architectural work. The design method used is the force based framework method. The force in the design of this building in addition to the surrounding natural environment is the natural perception of the community which is transformed into architectural forms. It aims to increase interest in training and restoring the user's physical and psychological health without having to go far out of town to look for nature.

題目設定引導設計邏輯發展之教學研究

建築學報 ◽  
2021 ◽  
Vol 116 (116-1) ◽  
pp. 055-061
Author(s):  
江梓瑋 江梓瑋
Keyword(s):  
Design Thinking ◽  
Design Method ◽  
Design Approach ◽  
Design Studio ◽  
Design Development ◽  
Specific Design ◽  
Direct Design ◽  
Operation Process ◽  
Thinking Process ◽  
Further Development

<p>傳統的建築設計課程皆以每學期幾次不同題型的設定，期望在設計操作的反復練習中，幫助操作者探索合適的操作方法並從中建立設計邏輯。設計題目的設定規範了操作的方向與期望的成果，但因設計發展並沒有既定的步驟與方法，常因個人經驗與所選擇設計方式的不同，導致過於感性的思維模式，也造就了理性建築設計教學的挑戰。此研究針對題目設定與設計邏輯的關係，試圖避開操作者可預期的結果，並藉過程中不同階段性的操作設定，試圖建立一種設計邏輯發展的依據。</p> <p>&nbsp;</p><p>Traditionally, architecture design studio requires few exercises per semester for students to practice design method and develop design thinking. As design exercises often direct design approach and also establish expectation of outcome, there is no guaranty procedure or design method to follow in order to achieve the best outcome. Since design development heavily based on experience of operation and choice of approach, sensible thinking process is often involved and sets challenge for rational architectural pedagogy. This research aims to exam the design thinking process of students by setting up specific design exercise to avoid predictable operation process, in order to direct specific design approach according to established guidance for further development. </p> <p>&nbsp;</p>

A Design Approach for Storage Spar Buoy Platforms in the Concept and Preliminary Design Phases

2002 ◽  
Author(s):  
Richard David Schachter ◽  
Carlos Gomes Jordani ◽  
Antonio Carlos Fernandes
Keyword(s):  
Weight Control ◽  
Method Development ◽  
Design Method ◽  
Design Approach ◽  
Preliminary Design ◽  
Concept Design ◽  
Structural Topology ◽  
General Arrangement ◽  
Control Stability ◽  
Definition Of

The objective of this work is to present a design approach for the Concept and Preliminary Design Phases of Storage SPAR Buoy Platforms and to describe how the design method was developed. The influence of a VIV porosity device on the design is taken into consideration. The inherent advantages of Spar concepts for Petrobras’ applications for 1250 m, are discussed and compared with other concepts. The Spar concept was chosen. The design method development was carried out by means of a brainstorming process, using sketches and the creation of interactive flowcharts of the design processes (similar to a design spiral) comprising the main design factors, their sequencing and interrelations, for both the Concept and Preliminary Design phases. The intent of the design approach is to provide the designer with means to define quick and efficiently the optimal hull dimensions for a pre-established scenario. For the Concept Design, the method includes the definition of the main dimensions, the Wellbay, the structural topology and compartmentation, general arrangement, weight control, stability (intact, damaged and flooded), motions and mooring. A discussion on the influence of the VIV porosity device on the dimensioning and mooring of the Spar Platform is provided. A concept design application example is presented.

Digital Controller Design Research Based on Series Compensation

2014 ◽  
Vol 1037 ◽  
pp. 294-298
Author(s):  
Yu Chuan Wu ◽  
Zheng Yan Gao Xu ◽  
Shuang Bao Ma
Keyword(s):  
Transfer Function ◽  
Design Research ◽  
Controller Design ◽  
Design Method ◽  
Design Approach ◽  
Digital Controller ◽  
Series Compensation ◽  
Compensation Design

By presetting correcting device transfer function D(z), this paper puts forward series compensation design approach of minimum beat system. Compared with tradition design method, this way is much simpler and easier.

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