Parametric optimization of anisogrid shells of irregular structure

2019 ◽  
Author(s):  
T.V. Burnysheva ◽  
O.A. Shteynbrekher
Keyword(s):  
Optimal Design ◽  
Parametric Optimization ◽  
Feasible Region ◽  
Irregular Structure ◽  
Simplex Search ◽  
Simplex Search Method ◽  
Rib Structure ◽  
Partial Predicate ◽  
Mesh Structures ◽  
Research Show

The paper focuses on an approach to solving the problem of parametric optimization of anisogrid mesh shells with an irregular structure. Mesh structures are widely used in building and engineering. This study deals with the optimal design of such structures used in aerospace industry. The problem of optimal design of mesh structures is relevant, as it makes it possible to increase the efficiency of their use, minimizing the weight, provided the strength and stability conditions are met. In our work we formulate the problem of optimal design of mesh structures in general form, and introduce an optimization algorithm based on the simplex search method in which we use a partial predicate of a feasible region to describe the non-convex smooth areas of boundaries. The results of solving the optimization problem for a particular structure with a violation of the regularity of the rib structure are given. Findings of research show that the considered algorithm can be used for optimal design of both regular and non-regular mesh structures.

An Efficient Hybrid Evolution Strategy Algorithm with Direct Search Method for Global Optimization

2019 ◽  
Vol 9 (3) ◽  
pp. 63-78
Author(s):  
Noureddine Boukhari ◽  
Fatima Debbat ◽  
Nicolas Monmarché ◽  
Mohamed Slimane
Keyword(s):  
Global Optimization ◽  
Adaptive Evolution ◽  
Optimization Problems ◽  
Search Method ◽  
Local Solution ◽  
Evolution Strategy ◽  
Direct Search Method ◽  
Simplex Search ◽  
Simplex Search Method ◽  
Restart Strategy

The main purpose of this article is to demonstrate how evolution strategy optimizers can be improved by incorporating an efficient hybridization scheme with restart strategy in order to jump out of local solution regions. The authors propose a hybrid (μ, λ)ES-NM algorithm based on the Nelder-Mead (NM) simplex search method and evolution strategy algorithm (ES) for unconstrained optimization. At first, a modified NM, called Adaptive Nelder-Mead (ANM) is used that exhibits better properties than standard NM and self-adaptive evolution strategy algorithm is applied for better performance, in addition to a new contraction criterion is proposed in this work. (μ, λ)ES-NM is balancing between the global exploration of the evolution strategy algorithm and the deep exploitation of the Nelder-Mead method. The experiment results show the efficiency of the new algorithm and its ability to solve optimization problems in the performance of accuracy, robustness, and adaptability.

scholarly journals Optimal Design of Single-Layered Reinforced Cylindrical Shells

2021 ◽  
Vol 24 (1) ◽  
pp. 58-64
Author(s):  
Heorhii V. Filatov ◽  
Keyword(s):  
Optimal Design ◽  
Numerical Experiment ◽  
Wall Thickness ◽  
Random Search ◽  
Cylindrical Shells ◽  
Compressive Load ◽  
Mathematical Programming Problem ◽  
Feasible Region ◽  
Shell Weight ◽  
Longitudinal Stiffeners

This paper discusses the application of the random search method for the optimal design of single-layered reinforced cylindrical shells operating in a neutral environment. When setting a mathematical programming problem, the minimum shell weight is considered as an objective function. The critical stresses are determined according to the linear theory in the elastic region of the material. As the constraints imposed on the feasible region, the constraints on the strength, general buckling and partial buckling of a shell are accepted. The aim of this paper is to study the weight efficiency of various types of shell reinforcements and the influence of an optimum-weight shell on the parameters of an axially-compressed one. A numerical experiment was carried out. Dependencies of shell weight, wall thickness, and reinforcement parameters on the magnitude of a compressive load were investigated for shells with different types of reinforcement. As a result of the numerical experiment performed, it was found that with an increase in compressive load magnitude, there is a tendency to an increase in the wall thickness of an optimal shell, with an increase in the thickness of longitudinal stiffeners (stringers) and a slight decrease in the number of ribs. In addition, it should be noted that the general case of buckling and the first special one turned out to be decisive in choosing optimal shell parameters.

Inverse Heat Transfer Analysis of Porous Extended Surface Using Simplex Search Method

2013 ◽  
Author(s):  
Rohit Kumar Singla ◽  
Ranjan Das ◽  
Arka Bhowmik ◽  
Ramjee Repaka
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Temperature Measurement ◽  
Thermal Conditions ◽  
Search Method ◽  
Heat Transfer Analysis ◽  
Critical Parameters ◽  
Simplex Search ◽  
Simplex Search Method ◽  
Extended Surface

This work deals with the application of the Nelder-Mead simplex search method (SSM) to study a porous extended surface. At first, analytical expression for calculating the local temperature field has been derived using an implicit Runge-Kutta method. The heat transfer phenomenon is assumed to be governed by conductive, naturally convective and radiative heat transfer, whereas the diffusion of mass through the porous media is also taken into account. Then, using the SSM, critical parameters such as porosity, permeability, and thermal conductivities of the extended surface have been predicted for satisfying a prescribed temperature field. It is found that many alternative solutions can meet a given thermal requirement, which is proposed to offer the flexibility in selecting the material and regulating the thermal conditions. It is observed that the allowable error in the temperature measurement should be limited within 5%. It is also found that even with few temperature measurement points, very good reconstruction of the thermal field is possible using the SSM.

A fin design employing an inverse approach using simplex search method

2013 ◽  
Vol 49 (7) ◽  
pp. 1029-1038 ◽  
Author(s):  
Ranjan Das ◽  
Ashis Mallick ◽  
K. T. Ooi
Keyword(s):  
Search Method ◽  
Inverse Approach ◽  
Simplex Search ◽  
Simplex Search Method ◽  
Fin Design

Extremal Behavior of One Parameter Families of Optimal Design Models

1989 ◽  
Author(s):  
J. R. J. Rao ◽  
P. Y. Papalambros
Keyword(s):  
Optimal Design ◽  
Parametric Optimization ◽  
Optimal Solution ◽  
Engineering System ◽  
Design Models ◽  
Numerical Examples ◽  
Mathematical Properties ◽  
Extremal Behavior ◽  
Rigorous Treatment ◽  
Multi Level

Abstract Optimal design models contain parameters that are considered fixed during the optimization process. When these parameters change values, the mathematical properties of the model and the physical behavior of the underlying engineering system may change drastically. This article examines how large changes in one parameter affect the optimal solution and the type of singularities that may be encountered. The theory presented extends parametric optimization beyond the usual sensitivity analysis, and can be used as a modeling tool or as a rigorous treatment of related problems, such as multi-level decomposition. The algorithmic implementation and numerical examples are presented in a sequel article.

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