A Hybrid Framework of Efficient Multi-Objective Optimization of Stiffened Shells with Imperfection

2019 ◽  
Vol 17 (04) ◽  
pp. 1850145 ◽  
Author(s):  
Hanshu Chen ◽  
Zeng Meng ◽  
Huanlin Zhou
Keyword(s):  
Carrying Capacity ◽  
Light Weight ◽  
Load Carrying Capacity ◽  
Weight Optimization ◽  
Multi Objective Optimization ◽  
Stiffened Shell ◽  
Multi Objective ◽  
Stiffened Shells ◽  
Load Carrying ◽  
Hybrid Framework

In the practical engineering applications of stiffened shell, the initial imperfection is inevitable and it could cause significant reduction in the load-carrying capacity of stiffened shell. The light-weight optimization of stiffened shell is generally performed under the constraint of fixed maximum load-carrying capacity. However, the load-carrying capacity of stiffened shell has been improved continuously as the promotion of manufacturing technology, which causes the previous strategies of light-weight optimization become conservative and outdated. Therefore, an improved hybrid framework of multi-objective optimization of stiffened shell with imperfection is necessary and presented in this paper, which focus on developing a general posterior design method to determine the optimal weight according to the different collapse loads. A new adaptive update criterion based on the Kriging model is developed to improve the efficiency and accuracy of the hybrid framework. The present optimal results provide a set of the Pareto optimal points and form a Pareto front, from which new posterior design can be achieved.

scholarly journals OPTIMIZATION OF GEOMETRICALLY NONLINEAR LATTICE GIRDERS. PART I: CONSIDERING MEMBER STRENGTHS

2015 ◽  
Vol 21 (4) ◽  
pp. 423-443 ◽  
Author(s):  
Tugrul Talaslioglu
Keyword(s):  
Optimization Algorithm ◽  
Carrying Capacity ◽  
Optimization Approach ◽  
Geometrically Nonlinear ◽  
Load Carrying Capacity ◽  
Multi Objective Optimization ◽  
Multi Objective ◽  
Load Carrying ◽  
Lattice Girder ◽  
Tubular Lattice

In this study, the entire weight, joint displacements and load-carrying capacity of tubular lattice girders are simultaneously optimized by a multi-objective optimization algorithm, named Non-dominated Sorting Genetic Algorithm II (NSGAII). Thus, the structural responses of tubular lattice girders are obtained by use of arc-length method as a geometrically nonlinear analysis approach and utilized to check their member strengths at each load step according to the provisions of the American Petroleum Institute specification (API RP2A-LRFD 1993). In order to improve the computing capacity of proposed optimization approach, while the optimization algorithm is hybridized with a radial basis neural network approach, an automatic lattice girder generator is included into the design stage. The improved optimization algorithm, called ImpNSGAII, is applied to both a benchmark lattice girder with 17 members and a lattice girder with varying span lengths and loading conditions. Consequently, it is demonstrated: 1) the optimal lattice girder configuration generated has a higher load-carrying capacity ensuring lower weight and joint displacement values; 2) the use of a multi-objective optimization approach increases the correctness degree in evaluation of optimality quality due to the possibility of performing a trade-off analysis for optimal designations; 3) the computing performance of ImpNSGAII is higher than NSGAII’s.

Multi-objective optimization of stacked radial passive magnetic bearing

2017 ◽  
Vol 232 (9) ◽  
pp. 1140-1159 ◽  
Author(s):  
KP Lijesh ◽  
Mrityunjay Doddamani ◽  
SI Bekinal ◽  
SM Muzakkir
Keyword(s):  
Carrying Capacity ◽  
Three Dimensional ◽  
Single Layer ◽  
Maximum Load ◽  
Magnetic Bearing ◽  
Load Carrying Capacity ◽  
Multi Objective Optimization ◽  
Design And Optimization ◽  
Multi Objective ◽  
Load Carrying

Modeling, design, and optimization for performances of passive magnetic bearings (PMBs) are indispensable, as they deliver lubrication free, friction less, zero wear, and maintenance-free operations. However, single-layer PMBs has lower load-carrying capacity and stiffness necessitating development of stacked structure PMBs for maximum load and stiffness. Present work is focused on multi-objective optimization of radial PMBs to achieve maximum load-carrying capacity and stiffness in a given volume. Three-dimensional Coulombian equations are utilized for estimating load and stiffness of stacked radial PMBs. Constraints, constants, and bounds for the optimization are extracted from the available literature. Optimization is performed for force and stiffness maximization in the obtained bounds with three PMB configurations, namely (i) mono-layer, (ii) conventional (back to back), and (iii) rotational magnetized direction. The optimum dimensions required for achieving maximum load without compromising stiffness for all three configurations is investigated. For designers ease, equations to estimate the optimized values of load, stiffness, and stacked PMB variables in terms of single-layer PMB are proposed. Finally, the effectiveness of the proposed method is demonstrated by considering the PMB dimensions from the available literature.

A New Type of Cast In Situ Reinforced Concrete Biaxial Hollow Slab with Property of Thermal Insulation

2011 ◽  
Vol 368-373 ◽  
pp. 448-451
Author(s):  
Wei Hong Xuan ◽  
Yong Wan ◽  
Yu Zhi Chen ◽  
Pan Xiu Wang
Keyword(s):  
Reinforced Concrete ◽  
Carrying Capacity ◽  
Fundamental Principle ◽  
Light Weight ◽  
Load Carrying Capacity ◽  
Construction Technology ◽  
Thermal Insulating ◽  
Load Carrying ◽  
New Type

The construction technology and fundamental principle of a new kind of cast-in-situ reinforced concrete biaxial hollow slab with property of thermal-insulating is proposed in this paper. Compared with ordinary floor, the biaxial hollow slab is well load-carrying capacity in two-direction, light weight and thermal -insulating property.

Influence of Yield Strength Variability over Cross-Section to Steel Beam Load-Carrying Capacity

2005 ◽  
Vol 10 (2) ◽  
pp. 151-160 ◽  
Author(s):  
J. Kala ◽  
Z. Kala
Keyword(s):  
Yield Strength ◽  
Cross Section ◽  
Carrying Capacity ◽  
Bending Moment ◽  
Statistical Characteristics ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Strength Variability ◽  
Hot Rolled ◽  
Hot Rolled Steel

Authors of article analysed influence of variability of yield strength over cross-section of hot rolled steel member to its load-carrying capacity. In calculation models, the yield strength is usually taken as constant. But yield strength of a steel hot-rolled beam is generally a random quantity. Not only the whole beam but also its parts have slightly different material characteristics. According to the results of more accurate measurements, the statistical characteristics of the material taken from various cross-section points (e.g. from a web and a flange) are, however, more or less different. This variation is described by one dimensional random field. The load-carrying capacity of the beam IPE300 under bending moment at its ends with the lateral buckling influence included is analysed, nondimensional slenderness according to EC3 is λ¯ = 0.6. For this relatively low slender beam the influence of the yield strength on the load-carrying capacity is large. Also the influence of all the other imperfections as accurately as possible, the load-carrying capacity was determined by geometrically and materially nonlinear solution of very accurate FEM model by the ANSYS programme.

Fuzzy Sets Theory in Comparison with Stochastic Methods to Analyse Nonlinear Behaviour of a Steel Member under Compression

2005 ◽  
Vol 10 (1) ◽  
pp. 65-75 ◽  
Author(s):  
Z. Kala
Keyword(s):  
Fuzzy Sets ◽  
Carrying Capacity ◽  
Stochastic Methods ◽  
Nonlinear Behaviour ◽  
Load Carrying Capacity ◽  
Load Carrying ◽  
Input Parameters ◽  
Stochastic Solution ◽  
Fuzzy Solution ◽  
Sets Theory

The load-carrying capacity of the member with imperfections under axial compression is analysed in the present paper. The study is divided into two parts: (i) in the first one, the input parameters are considered to be random numbers (with distribution of probability functions obtained from experimental results and/or tolerance standard), while (ii) in the other one, the input parameters are considered to be fuzzy numbers (with membership functions). The load-carrying capacity was calculated by geometrical nonlinear solution of a beam by means of the finite element method. In the case (ii), the membership function was determined by applying the fuzzy sets, whereas in the case (i), the distribution probability function of load-carrying capacity was determined. For (i) stochastic solution, the numerical simulation Monte Carlo method was applied, whereas for (ii) fuzzy solution, the method of the so-called α cuts was applied. The design load-carrying capacity was determined according to the EC3 and EN1990 standards. The results of the fuzzy, stochastic and deterministic analyses are compared in the concluding part of the paper.

Pavement Damage Due to Conventional and New Generation of Wide-Base Super Single Tires

2005 ◽  
Vol 33 (4) ◽  
pp. 210-226 ◽  
Author(s):  
I. L. Al-Qadi ◽  
M. A. Elseifi ◽  
P. J. Yoo ◽  
I. Janajreh
Keyword(s):  
Carrying Capacity ◽  
Material Properties ◽  
Three Dimensional ◽  
Fe Analysis ◽  
Load Carrying Capacity ◽  
Inflation Pressure ◽  
3D Finite Element ◽  
Load Carrying ◽  
Pavement Damage ◽  
New Generation

Abstract The objective of this study was to quantify pavement damage due to a conventional (385/65R22.5) and a new generation of wide-base (445/50R22.5) tires using three-dimensional (3D) finite element (FE) analysis. The investigated new generation of wide-base tires has wider treads and greater load-carrying capacity than the conventional wide-base tire. In addition, the contact patch is less sensitive to loading and is especially designed to operate at 690kPa inflation pressure at 121km/hr speed for full load of 151kN tandem axle. The developed FE models simulated the tread sizes and applicable contact pressure for each tread and utilized laboratory-measured pavement material properties. In addition, the models were calibrated and properly validated using field-measured stresses and strains. Comparison was established between the two wide-base tire types and the dual-tire assembly. Results indicated that the 445/50R22.5 wide-base tire would cause more fatigue damage, approximately the same rutting damage and less surface-initiated top-down cracking than the conventional dual-tire assembly. On the other hand, the conventional 385/65R22.5 wide-base tire, which was introduced more than two decades ago, caused the most damage.

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