Elasto-Plastic Properties of Thin-Walled Structures Designed with the SADSF Method

2015 ◽  
Vol 240 ◽  
pp. 206-211
Author(s):  
Ireneusz Markiewicz
Keyword(s):  
Lower Bound ◽  
Approximate Method ◽  
Limit Analysis ◽  
Limit State ◽  
Stress Fields ◽  
Application Software ◽  
Plastic Properties ◽  
Thin Walled Structures ◽  
Bound Theorem ◽  
Thin Walled

The paper presents a selected example of investigations, carried out by the author, on complex thin-walled structures [3] that were designed based on the method of statically admissible discontinuous stress fields (the SADSF method, [1,2,4,5]) with the condition of equalized effort in the limit state. The SADSF method is substantiated based on the conclusions that follow on the lower bound theorem of limit analysis, and is an approximate method. The aim of the investigations was practical verification of solutions of the SADSF method in elasto-plastic and elastic range of stress, because these ranges are not taken into account in the method. The existing application software of the SADSF method allows one to design very complex thin-walled structures which are free of cardinal errors. Moreover, the method can be easily used by practically any engineer.

scholarly journals Design With SADSF Method and Analyses of Elastic Properties of Torsion-Loaded Double-Tee Section With Torsional Box

2019 ◽  
Vol 24 (1) ◽  
pp. 79-89
Author(s):  
I. Markiewicz
Keyword(s):  
Elastic Properties ◽  
Limit State ◽  
Equivalent Stress ◽  
Stress Fields ◽  
Strength Design ◽  
Torsion Moment ◽  
Load Carrying ◽  
Thin Walled ◽  
Better Than

Abstract The work presents the results of preliminary strength design of a thin-walled structure based on double-tee section loaded with a torsion moment. One of the solutions to this problem is considered, in which the torsional box is introduced in the central part. Then, one constructs a series of solution variants that differ in the torsional box length. In the design one uses the method of statically admissible discontinuous stress fields (SADSF) assuming the condition of equalized equivalent stress in the limit state. The work is complemented with elastic FEM analyses of one of the solution variants. Using this example, one shows good load-carrying properties of structures designed with the SADSF method, and proves that they could be several times better than the properties of structures designed with traditional or intuitive ways.

scholarly journals Discrete Limit Analysis of Thin-Walled Structures (Part 1)

1981 ◽  
Vol 1981 (150) ◽  
pp. 389-397
Author(s):  
Yutaka Toi ◽  
Masatoshi Ueda ◽  
Kouji Yamamoto ◽  
Tadahiko Kawai
Keyword(s):  
Limit Analysis ◽  
Thin Walled Structures ◽  
Thin Walled

Ultimate Limit State Equations and Plasticity of Tubular Conical Transitions

2020 ◽  
Vol 143 (3) ◽  
Author(s):  
Albert Ku ◽  
Jieyan Chen
Keyword(s):  
Lower Bound ◽  
Edge Effects ◽  
Limit Analysis ◽  
Oil And Gas ◽  
Limit State ◽  
Ultimate Limit State ◽  
Design Standards ◽  
State Equations ◽  
Sharp Stress ◽  
Ultimate Limit

Abstract Conical transitions have wide applications in wind turbine foundation as well as oil and gas jacket type of structures. The junctions where tubular and cone meet experience a sharp stress rise from shell edge effects. Like all structures experiencing sharp stress rises, fatigue considerations are critical. In addition to fatigue, the existing offshore structural design standards also require ultimate limit state checks. It is known from the lower bound theorem of plasticity limit analysis that the junction local edge effects do not impact the global capacity. Designing for the local junction ultimate limit state contains wide variations among existing design standards. In this paper, the design practices from API RP-2A, NORSOK N-004, and ISO 19902:2020 draft are assessed. They are compared to the shell plastic yield criteria of Hodge and Ilyushin. In addition, this paper provides a semi-analytical plasticity solution to determine junction plastic deformations. The formulation is based on cylindrical shell equations coupled with deformation plasticity theory. It is found that the growth of the junction plasticity zone is limited, which is consistent with the anticipation from the lower bound limit analysis theorem. The observations made in this paper show that the local junction plasticity is a secondary issue compared to other design considerations. Its ultimate limit state design equation can afford to be more lenient if chooses for future standards’ development.

Review of Lower-Bound Limit Analysis for Pressure Vessel Intersections

1977 ◽  
Vol 99 (3) ◽  
pp. 413-418 ◽  
Author(s):  
A. Biron
Keyword(s):  
Lower Bound ◽  
Lower Bounds ◽  
Limit Analysis ◽  
Pressure Vessel ◽  
General Purpose ◽  
Collapse Load ◽  
Rotationally Symmetric ◽  
Bound Theorem ◽  
Symmetric Structures ◽  
Lower Bound Limit Analysis

On the basis of a study of several recent papers concerned with the lower-bound computation of the collapse load of pressure vessel intersections, a review is made of the satisfaction, or nonsatisfaction, of the requirements of the lower-bound theorem of limit analysis. It is shown that, whereas for rotationally symmetric structures true lower bounds have been obtained, for a nonsymmetric case such as a right cylinder-cylinder intersection it is difficult to avoid so me approximations. If attempts are to be made to develop general purpose limit analysis programs, the consequences of approximations of the type used so far must be evaluated with care if significant results are to be obtained.

An Evaluation of ASME Ellipsoidal Heads

1969 ◽  
Vol 91 (3) ◽  
pp. 636-640 ◽  
Author(s):  
R. R. Gajewski ◽  
R. H. Lance
Keyword(s):  
Linear Programming ◽  
Lower Bound ◽  
Programming Problem ◽  
Lower Bounds ◽  
Limit Analysis ◽  
Digital Computer ◽  
Linear Programming Problem ◽  
Pressure Vessels ◽  
Asme Code ◽  
Bound Theorem

The ASME Code specifications for unfired cylindrical pressure vessels are examined from the viewpoint of the lower bound theorem of limit analysis. The problem is formulated as a linear programming problem and numerically solved using well-established algorithms on a digital computer. It is shown that lower bounds for collapse are less than the ASME Code specifications for such structures.

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