Shape Optimization of a Double-Layer Space Truss Described by a Parametric Surface

1997 ◽  
Vol 12 (2) ◽  
pp. 109-119 ◽  
Author(s):  
M. Ohsaki ◽  
Tsuneyoshi Nakamura ◽  
M. Kohiyama
Keyword(s):  
Double Layer ◽  
Layer Surface ◽  
Optimal Solutions ◽  
Parametric Surface ◽  
Cross Sectional ◽  
Space Truss ◽  
Design Variables ◽  
Lattice Space ◽  
Control Net ◽  
Structural Volume

A method is presented for finding the optimal configuration of a double-layer space truss described by a parametric surface. The number of design variables is drastically reduced, without sacrificing the smoothness of the upper layer surface, by using the control net parameters as design variables. The coordinates of the lower nodes are defined by using a vertical or normal offset vectors from the upper surface. Curvatures of the curve associated with the lower polygon are calculated for evaluating feasibility and regularity of the a double-layer lattice space truss. In the examples, a feasible optimum design, which minimizes compliance under constraints on structural volume, are successfully found by using the proposed method. It is shown that the optimal solutions strongly depend on the specified ratios of the cross-sectional areas of the members.

Comparison of four meta-heuristic algorithms for optimal design of double-layer barrel vaults

2018 ◽  
Vol 33 (3-4) ◽  
pp. 115-123
Author(s):  
Ali Kaveh ◽  
Majid Ilchi Ghazaan ◽  
Soroush Mahjoubi
Keyword(s):  
Optimal Design ◽  
Double Layer ◽  
Heuristic Algorithms ◽  
Size Optimization ◽  
Community Centers ◽  
Cross Sectional ◽  
Long Span ◽  
Design Variables ◽  
Rail Station ◽  
Barrel Vaults

Barrel vaults are effective semi-cylindrical forms of roof systems that are widespread for multipurpose facilities including warehouse, rail station, pools, sports center, airplane hungers, and community centers because of providing long-span and economical roof with significant amount of space underneath. In the present study, size optimization of double-layer barrel vaults with different configurations is studied. Four recently developed algorithms consisting of the CBO, ECBO, VPS, and MDVC-UVPS are employed and their performances are compared. The structures are subjected to stress, stability, and displacement limitations according to the provisions of AISC-ASD. The design variables are the cross-sectional areas of the bar elements which are selected from steel pipe sections. The numerical results indicate that the MDVC-UVPS outperforms the other algorithms in finding optimal design in all examples.

scholarly journals Optimization Of Double-Layer Braced Barrel Vaults

2015 ◽  
Vol 15 (2) ◽  
Author(s):  
Maksym Grzywiński
Keyword(s):  
Double Layer ◽  
Discrete Optimization ◽  
Optimization Problem ◽  
Limit State ◽  
Discrete Optimization Problem ◽  
Cross Sectional ◽  
Optimization Constraints ◽  
Space Design ◽  
Design Variables ◽  
Structural Space

Abstract The paper deals with discussion of discrete optimization problem in civil engineering structural space design. Minimization of mass should satisfy the limit state capacity and serviceability conditions. The cross-sectional areas of truss bars are taken as design variables. Optimization constraints concern stresses, displacements and stability, as well as technological and computational requirements.

scholarly journals Prediction of Optimal Design and Deflection of Space Structures Using Neural Networks

2012 ◽  
Vol 2012 ◽  
pp. 1-18 ◽  
Author(s):  
Reza Kamyab Moghadas ◽  
Kok Keong Choong ◽  
Sabarudin Bin Mohd
Keyword(s):  
Neural Networks ◽  
Optimal Design ◽  
Double Layer ◽  
Optimization Problem ◽  
Computational Cost ◽  
Space Structures ◽  
Maximum Deflection ◽  
Cross Sectional ◽  
Design Variables ◽  
Low Computational Cost

The main aim of the present work is to determine the optimal design and maximum deflection of double layer grids spending low computational cost using neural networks. The design variables of the optimization problem are cross-sectional area of the elements as well as the length of the span and height of the structures. In this paper, a number of double layer grids with various random values of length and height are selected and optimized by simultaneous perturbation stochastic approximation algorithm. Then, radial basis function (RBF) and generalized regression (GR) neural networks are trained to predict the optimal design and maximum deflection of the structures. The numerical results demonstrate the efficiency of the proposed methodology.

scholarly journals Genetic Algorithm Optimization of the Volute Shape of a Centrifugal Compressor

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Martin Heinrich ◽  
Rüdiger Schwarze
Keyword(s):  
Numerical Model ◽  
Centrifugal Compressor ◽  
Total Pressure ◽  
Pressure Ratio ◽  
Pressure Rise ◽  
Maximum Efficiency ◽  
Algorithm Optimization ◽  
Cross Sectional ◽  
Design Variables ◽  
Design Speed

A numerical model for the genetic optimization of the volute of a centrifugal compressor for light commercial vehicles is presented. The volute cross-sectional shape is represented by cubic B-splines and its control points are used as design variables. The goal of the global optimization is to maximize the average compressor isentropic efficiency and total pressure ratio at design speed and four operating points. The numerical model consists of a density-based solver in combination with the SSTk-ωturbulence model with rotation/curvature correction and the multiple reference frame approach. The initial validation shows a good agreement between the numerical model and test bench measurements. As a result of the optimization, the average total pressure rise and efficiency are increased by over1.0%compared to the initial designs of the optimization, while the maximum efficiency rise is nearly 2.5% atm˙corr=0.19 kg/s.

Multi Objective Design Optimization of Two Bar Truss Using NSGA II and TOPSIS

2014 ◽  
Vol 984-985 ◽  
pp. 419-424
Author(s):  
P. Sabarinath ◽  
M.R. Thansekhar ◽  
R. Saravanan
Keyword(s):  
Design Optimization ◽  
Optimization Problems ◽  
Optimization Methods ◽  
Optimal Solutions ◽  
Objective Functions ◽  
Nsga Ii ◽  
Multi Objective ◽  
Total Displacement ◽  
Design Variables ◽  
Conflicting Objectives

Arriving optimal solutions is one of the important tasks in engineering design. Many real-world design optimization problems involve multiple conflicting objectives. The design variables are of continuous or discrete in nature. In general, for solving Multi Objective Optimization methods weight method is preferred. In this method, all the objective functions are converted into a single objective function by assigning suitable weights to each objective functions. The main drawback lies in the selection of proper weights. Recently, evolutionary algorithms are used to find the nondominated optimal solutions called as Pareto optimal front in a single run. In recent years, Non-dominated Sorting Genetic Algorithm II (NSGA-II) finds increasing applications in solving multi objective problems comprising of conflicting objectives because of low computational requirements, elitism and parameter-less sharing approach. In this work, we propose a methodology which integrates NSGA-II and Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) for solving a two bar truss problem. NSGA-II searches for the Pareto set where two bar truss is evaluated in terms of minimizing the weight of the truss and minimizing the total displacement of the joint under the given load. Subsequently, TOPSIS selects the best compromise solution.

Sensitivity of Composite and Non-Composite Space Trusses to Member Loss

1994 ◽  
Vol 9 (2) ◽  
pp. 107-119 ◽  
Author(s):  
Ahmed El-Sheikh
Keyword(s):  
Double Layer ◽  
Concrete Slab ◽  
Noticeable Effect ◽  
Composite Action ◽  
Space Truss ◽  
Space Trusses ◽  
Loss Factors

Since double layer space trusses have typically a large number of redundant members, it is frequently assumed that they are quite safe as the loss of one or more members can be accommodated without any noticeable effect on truss overall behaviour. The present study shows that every truss includes a number of critical members, the loss of any of which would cause force distributions that could lead to an overall premature collapse. The sensitivity of space trusses to member loss is clearly identified. The composite action between a top concrete slab and a space truss is also introduced as a means to control truss sensitivity to member loss. Factors that affect this sensitivity such as the truss supporting conditions are also investigated.

Evaluation of cesarean scar after single- and double-layer hysterotomy closure: a prospective cross-sectional study

2018 ◽  
Vol 297 (5) ◽  
pp. 1137-1143 ◽  
Author(s):  
Nur Betül Tekiner ◽  
Berna Aslan Çetin ◽  
Lale Susan Türkgeldi ◽  
Gökçe Yılmaz ◽  
İbrahim Polat ◽  
...  
Keyword(s):  
Double Layer ◽  
Cross Sectional Study ◽  
Sectional Study ◽  
Cross Sectional ◽  
Cesarean Scar

A fast multiobjective optimization approach to S-duct scoop inlets design with both inflow and outflow

2018 ◽  
Vol 233 (9) ◽  
pp. 3381-3394
Author(s):  
Lifang Zeng ◽  
Dingyi Pan ◽  
Shangjun Ye ◽  
Xueming Shao
Keyword(s):  
Multiobjective Optimization ◽  
Total Pressure ◽  
Optimization Method ◽  
Navier Stokes ◽  
Integral Model ◽  
Optimization Approach ◽  
Navier Stokes Equation ◽  
Cross Sectional ◽  
Design Variables ◽  
Computational Fluid Dynamics Analysis

A fast multiobjective optimization method for S-duct scoop inlets considering both inflow and outflow is developed and validated. To reduce computation consumption of optimization, a simplified efficient model is proposed, in which only inflow region is simulated. Inlet pressure boundary condition of the efficient model is specified by solving an integral model with both inflow and outflow. An automated optimization system integrating the computational fluid dynamics analysis, nonuniform rational B-spline geometric representation technique, and nondominated sorting genetic algorithm II is developed to minimize the total pressure loss and distortion at the exit of diffuser. Flow field is numerically simulated by solving the Reynolds-averaged Navier–Stokes equation coupled with k–ω shear stress transport turbulence model, and results are validated to agree well with previous experiment. S-duct centreline shape and cross-sectional area distribution are parameterized as the design variables. By analyzing the results of a suggested optimal inlet chosen from the obtained Pareto front, total pressure recovery has increased from 97% to 97.4%, and total pressure distortion DC60 has decreased by 0.0477 (21.7% of the origin) at designed Mach number 0.7. The simplified efficient model has been validated to be reliable, and by which the time cost for the optimization project has been reduced by 70%.

Shape Opimization of Femoral Components of an Artificial Hip Prosthesis Using the Three-Dimensional P-Version Finite Element Method

2001 ◽  
Author(s):  
Masaru Higa ◽  
Ikuya Nishimura ◽  
Hiromasa Tanino ◽  
Yoshinori Mitamura
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Hip Prosthesis ◽  
Three Dimensional ◽  
Optimization Procedure ◽  
Peak Stress ◽  
Cross Sectional ◽  
Design Variables ◽  
Dimensional Shape ◽  
Element Method

Abstract The three-dimensional shape optimization of cemented total hip arthroplasty (THA) was introduced in this paper. The P-version Finite Element Method (FEM) combined with an optimization procedure was used to minimize the peak stress in the bone cement near the tip of the implant. Six-design variables were used in this study. Each variable represents the dimension of the medial-lateral width and anterior-posterior width of the three levels (proximal, distal and middle) of cross sectional area of the prosthesis. The results of the design optimization showed considerable reduction in stress concentration compared to the initial design that is currently used clinically.

Antiicing Properties of Bioinspired Liquid‐Infused Double‐Layer Surface with Internal Wetting Transport Ability

2019 ◽  
Vol 6 (10) ◽  
pp. 1900244 ◽  
Author(s):  
Zhenyu Guo ◽  
Chunlei Gao ◽  
Jinghui Li ◽  
Yufang Liu ◽  
Yongmei Zheng
Keyword(s):  
Double Layer ◽  
Layer Surface
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