Minimum Weight Optimization of Offshore Jackets

1991 ◽  
Vol 113 (4) ◽  
pp. 292-296
Author(s):  
V. S. R. Murty ◽  
C. L. Rao ◽  
K. Rajagopalan
Keyword(s):  
Minimum Weight ◽  
Wave Forces ◽  
Weight Optimization ◽  
Wave Direction ◽  
Minimum Weight Design ◽  
Cross Sectional ◽  
Space Truss ◽  
The World ◽  
Weight Design ◽  
Period Wave

Offshore steel jackets are extensively used all over the world for the extraction of hydrocarbons from the reservoirs lying underneath the seabed. In this paper, the results of research carried out by the authors on the minimum weight optimization of the jacket for wave forces have been described. The gradient projection method has been used in the optimization. The jacket is modeled as a space truss and the cross-sectional areas of the tubular members have been the variables in the optimization process. The optimization histories with different sets of group area variables have been presented. The minimum weight design has been repeated over a range of ocean wave parameters, such as wave period, wave height, and wave direction, and the results are presented to indicate their interplay in the optimal picture.

Analytic Treatment of Minimum Weight Design of Cantilevers

1974 ◽  
Vol 41 (2) ◽  
pp. 512-515
Author(s):  
J. E. Brock
Keyword(s):  
Analytic Solution ◽  
Minimum Weight ◽  
Practical Importance ◽  
Cantilever Beams ◽  
Minimum Weight Design ◽  
Concentrated Force ◽  
Cross Sectional ◽  
Section Modulus ◽  
End Conditions ◽  
Weight Design

Minimum weight design is considered for cantilever beams which must sustain a concentrated moment and a concentrated force at the tip as well as their own distributed weight. An analytic solution is obtained for the case where the variation of cross section is such that section modulus varies as a power of cross-sectional area. Three cases, having practical importance, are studied in detail; two of these lead to nonlinear differential or integral relationships. Cases having more complicated laws of variation and other end conditions are discussed.

scholarly journals Optimal Mass Design of 25 Bars Truss with Loading Conditions on Five Node Elements

2019 ◽  
Vol 4 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Koumbe Mbock ◽  
Etoua Remy Magloire ◽  
Lezin Seba Minsili ◽  
Okpwe Mbarga Richard
Keyword(s):  
Minimum Weight ◽  
Elastic Model ◽  
Loading Conditions ◽  
Cross Sectional ◽  
Linear Elastic ◽  
Space Truss ◽  
Mass Minimization ◽  
Internal Forces ◽  
Minimum Displacement ◽  
Weight Design

The optimal design of a twenty-five bar space truss commonly involves multiple loading conditions acting on 4 node elements in the linear elastic model. In this paper, we describe the behavior of the truss system with our experimental loading conditions on five node elements subject to minimum displacement and stresses that are used to formulate the constrained nonlinear optimization problem. Numerical computations are developed with the objective of mass minimization and the best structural design is selected by applying the interior point method with the guidance of Matlab Optimization Toolbox. Our numerical results show the optimal values of cross-sectional areas, material densities, and internal forces which satisfy the minimum weight design. These results provide the appropriate mass to the experimental data and allow substantial changes in size, shape, and topology.

Influences of Uncertainties on Mechanical Behavior of a Double-Layer Space Truss

1992 ◽  
Vol 7 (3) ◽  
pp. 223-235 ◽  
Author(s):  
Akira Wada ◽  
Zhu Wang
Keyword(s):  
Mechanical Behavior ◽  
Double Layer ◽  
Human Error ◽  
Minimum Weight ◽  
Initial Imperfection ◽  
Minimum Weight Design ◽  
Space Truss ◽  
The Monte Carlo Method ◽  
Weight Design ◽  
Statistical Studies

A space truss, as all other structures, is constantly subject to various types of uncertainties. For the purpose of estimating, and furthermore, ensuring the safety of a space truss, it is important to investigate its mechanical behavior with consideration of the influences of uncertainties. A 6 × 6 square-plan, double-layer space truss is designed in accordance with minimum weight design concept and used as an example to study. A computer program is written to analyze the truss structure, with an ability to simulate member buckling. The Monte Carlo method is applied for statistical studies with trial number of each study set to 100. The variation of member strength, initial imperfection of member length are chosen for component uncertainties, and the error in assembly process is chosen for human error. The mechanical behavior of the space truss influenced by these uncertainties is studied. A comparison between the influences of the component's uncertainties originating in human error, is made to determine where the most critical uncertainties lie.

Minimum-Weight Design of Thin-Walled Cylinders Subject to Flexural and Torsional Stiffness Constraints

1980 ◽  
Vol 47 (1) ◽  
pp. 106-110 ◽  
Author(s):  
R. D. Parbery ◽  
B. L. Karihaloo
Keyword(s):  
Minimum Weight ◽  
Torsional Stiffness ◽  
Contour Length ◽  
Minimum Weight Design ◽  
Cross Sectional ◽  
Weight Design ◽  
Thin Walled ◽  
Sectional Shape ◽  
Elliptical Cylinders ◽  
Walled Cylinder

We consider the problem of determining the cross-sectional shape of a thin-walled cylinder of constant (unknown) wall thickness and given contour length that uses the least possible material to achieve prescribed minimum stiffness in torsion and bending. The corresponding variational problem is shown to belong to a class with nonadditive functionals whose Euler equation is an integrodifferential equation. Cross-sectional shapes are presented for various stiffness ratios and compared with circular and elliptical cylinders.

Minimum Weight Design of Ring Stiffened Cylinders Under External Pressure

1961 ◽  
Vol 5 (03) ◽  
pp. 44-49 ◽  
Author(s):  
George Gerard
Keyword(s):  
Yield Strength ◽  
Minimum Weight ◽  
External Pressure ◽  
Compressive Yield Strength ◽  
Minimum Weight Design ◽  
Weight Design

Minimum weight analyses for unstiffened and ring-stiffened cylinders under external pressure are presented for designs based on stability and compressive yield-strength considerations. The results for both types of cylinders are compared in terms of a common set of parameters to establish the efficiency of the stiffening system. The results are then compared on a somewhat different basis to establish the relative efficiencies of various classes of materials. Finally, certain conclusions are drawn of particular pertinence to deep submersibles.

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