Layout Optimization Of Structures Research Articles

Принципы и современные методы оптимального проектирования крупногабаритных судовых перекрытий

Based on the previously developed approach to structural ship design, the authors optimize a large-span deck grillage taking into account several design loading scenarios. Topological optimization made it possible to find an optimal structural layout of the grillage, and parametric optimization yielded the scantlings of beams and simultaneously reduced grillage weight. Additional gain in structural weight was achieved by means of the openings in beam webs.

Size, Layout, and Topology Optimization of Skeletal Structures Using Plasma Generation Optimization

In this paper, plasma generation optimization (PGO) as a newly developed physics-based metaheuristic algorithm is applied to perform the size, layout, and topology optimization problems of skeletal structures. PGO is a population-based optimizer inspired by the process of plasma generation. In this optimization method, each agent is modeled as an electron. The movement of electrons and changing their energy level are performed based on simulating the process of excitation, de-excitation, and ionization. These processes occur iteratively through the plasma generation. Evaluating the robustness and performance of the PGO is illustrated through six design examples for different types of structural optimization. The results reveal that the PGO algorithm outperforms other state-of-the-art optimization techniques considered from the literature.

Simultaneous sizing, shape, and layout optimization and automatic member grouping of dome structures

This paper presents both discrete and continuous sizing, shape, and layout structural optimization problems concerning the weight minimization of dome structures and considering displacements, stresses, natural frequencies of vibration, and global stability as constraints. The layout optimization searches for the best structural configuration through the maintenance of the bars’ grouping by introducing a new design variable. This variable refers to the number of standard modules used to generate the structural configuration of optimized domes. It can be attractive to use a reduced number of distinct cross-sectional areas, minimizing the costs of fabrication, transportation, storing, checking, and welding, providing labor saving measures. To obtain an automatic member grouping of the bars of the trusses analyzed in this paper, a specific encoding using cardinality constraints is considered. As result, trade-off curves are provided, showing the optimized weights in comparison with the number of distinct cross-sectional areas used in the solutions. Differential Evolution is the search algorithm adopted in this paper. The structural optimization problems showed better solutions when compared with those presented in the literature.

Three-dimensional validation and analyses of the optimized CFETR HCCB blanket

The Helium Cooled Ceramic Breeder (HCCB) blanket is the critical component of the China Fusion Engineering Test Reactor (CFETR). The radial structural layout of the internal functional zones has the largest impact on the neutronics and thermal-hydraulic performance of the blanket, and it’s also the major determinant for the detailed 3D design. In the previous work, NTCOC, a Neutronics/Thermal-hydraulic Coupling Optimization Code, has been developed for application in the radial structural layout optimization of the CFETR HCCB blanket. However, for increasing the optimization efficiency, the NTCOC employs the simplified 1D neutronics and 2D thermal-hydraulic calculation models, the results of which may differ from the calculation results of the 3D actual models. Therefore, it’s essential to verify the reliability of the simplified models by comparing their calculation results with the corresponding 3D models. In this work, both the 3D neutronics and thermal-hydraulic analyses corresponding to the radial structural optimization processes of the CFETR HCCB blanket are performed and the corresponding calculation results are compared with NTCOC. The results show that adopting the 1D neutronics model in NTCOC can reflect the change tendency of the tritium breeding performance during the radial optimization processes accurately. However, the radial temperature distribution which is calculated by the 3D thermal-hydraulic model is generally higher than the NTCOC results, which means that the direct application of the 2D thermal-hydraulic model in NTCOC is not conservative. For solving this problem, a 3D thermal revision is added to the previous optimization method in the form of feedback. After revision, the 3D calculated temperature of the newly obtained blanket scheme is generally lower than the NTCOC’s, which means that the previous problem has been well solved. This work comprehensively verifies the reliability of the NTCOC and the improved optimization method after the 3D thermal revision for application in the radial structural optimization of the CFETR HCCB blanket.

A local mesh reconstruction method for layout and scantling optimization of FPSO internal turret area structure

This paper proposes a local mesh reconstruction method designed for generating the finite element (FE) analysis model in the context of simultaneous layout and scantling optimization. The FE model is automatically built by inheriting the topology and property information of the prepared initial finite element (FE) analysis model. A framework of optimization integrating the mesh reconstruction process is set up through the ISIGHT platform based on MATLAB code and MSC.PATRAN&NASTRAN. The capability and effectiveness of the method are demonstrated on the optimization of a typical internal turret area for the mooring system of FPSO. The thickness of plates and the layout of web-frames are optimized to minimize the structural weight of the turret area subjected to yield stress constraints. The optimization result presents the potential application of the proposed method in layout and scantling optimization of the FPSO internal turret area structure.

A new method for improving the tritium breeding and releasing performance of China Fusion Engineering Test Reactor phase II helium‐cooled ceramic breeder blanket

China Fusion Engineering Test Reactor (CFETR) is a brand new Tokamak reactor which is currently being designed to fill the intervals between ITER and future DEMO fusion reactor. It has two operation phases: phase I with Pf = 200 MW is to demonstrate steady-state operation; phase II with Pf = 1000 MW to validate DEMO technology. Helium-cooled ceramic breeder (HCCB) blanket is one of the candidate blanket concepts for CFETR. Until now, there are many research institutes which have performed conceptual designs and comprehensive analyses works for phase I HCCB blanket in detail. However, lately, the operational stage of CFETR has transformed from phase I to phase II, and the latest core design parameters have been just determined (major radius equals to 7.2 m, minor radius equals to 2.2 m). Therefore, the design and analyses work for HCCB blanket should also be initialized. In this work, based on the original integrated optimization method, the radial structure layout optimization of the outboard equatorial phase II HCCB blanket module is conducted by NTCOC. However, the calculation results show that the original optimization method provides inadequately optimized tritium breeding performance and insufficient tritium releasing ability under the condition of high fusion power. To solve these problems, a dynamic feedback is incorporated into the original optimization method for the first time, and then the calculation results show that the problem has been solved well after revision. This work can supply worthy guidance and reference for the conceptual design and comprehensive analyses of CFETR phase II HCCB blanket.

Size/Layout Optimization of Truss Structures Using Shuffled Shepherd Optimization Method

The main purpose of this paper is to investigate the ability of the recently developed multi-community meta-heuristic optimization algorithm, shuffled shepherd optimization algorithm (SSOA), in layout optimization of truss structures. The SSOA is inspired by mimicking the behavior of shepherd in nature. In this algorithm, agents are first divided into communities which are called herd and then optimization process, inspired by the shepherd’s behavior in nature, is operated on each community. The new position of agents is obtained using elitism technique. Then communities are merged for sharing the information. The results of SSOA in layout optimization show that SSOA is competitive with other considered meta-heuristic algorithms.

Size and layout optimization of truss structures with dynamic constraints using the interactive fuzzy search algorithm

Optimizing truss structures considering natural frequency constraints can fundamentally enhance their dynamic behaviour under transient loadings. In this regard, the current investigation assesses the search capability of the interactive fuzzy search algorithm (IFSA) in solving this class of problem. Since the natural frequencies are very sensitive to configuration changes in the system, throughout the optimization process the algorithm should be able to adaptively shift its search behaviour. To meet this aim, the IFSA utilizes two nine-rule fuzzy modules which permanently monitor the optimization process and try to balance the exploration and exploitation search behaviours of the algorithm. Then, the search capability of the proposed method is tested on five structural benchmark problems. The numeric results reveal that the IFSA, by systematically reducing the number of ineffective iterations, considerably decreases the required computational cost. In addition, considering solution accuracy and process stability, IFSA provides promising results in solving structural optimization problems.

Correction to: Layout optimization of continuum structures embedded with movable components and holes simultaneously

The original version of this article unfortunately contained a mistake. The Figure 11 in the original article should be replaced by the following figure.

Study of Structural Periodic-like Layout Optimization Based on Guide-weight Method

Study of Structural Periodic-like Layout Optimization Based on Guide-weight Method

СТРУКТУРНО-КОМПОНОВОЧНЫЙ СИНТЕЗ ПОДСИСТЕМ МОДУЛЕЙ ДЛЯ ВНУТРЕННЕЙ РЕЗЬБООБРАБОТКИ

The article presents the results of research in the direction of improving technological equipment for internal threading of parts in a flexible automated production. The creation of effective technological equipment for automated thread processing is an urgent task, the solution of which is associated with obtaining a significant economic effect by increasing processing productivity and improving product quality. An enlarged block diagram of the sequence of solving the synthesis problem, identifying "weak" places (elements and nodes that significantly reduce the reliability and readjustability of the system) and improving the elements of the equipment technological system is presented. After filling in the morphological matrix for the threading module system, a synthesis of its structure variants is performed. The measures taken allow us to solve the synthesis problem at the level of structural-layout optimization.

Stiffener layout optimization of plate and shell structures for buckling problem by adaptive growth method

Under axial pressure or shear load, thin-walled plate and shell structures are easily destroyed by buckling. This paper presents the design method for finding the optimal stiffener layout on thin-walled plate and shell structures against the buckling by using the adaptive growth method (AGM), which is based on the growth mechanism of branch systems in nature. Firstly, a mathematical model for optimization of the stiffener layout against buckling is established, and a Karush-Kuhn-Tucker (KKT)-based iteration formula is derived. Next, the stiffeners grow or degenerate from “seeds” according to the adaptive growth principle. Several examples, including imperforated and perforated rectangular plates with unilateral axial pressure and shear loading, are demonstrated to validate the effectiveness of the suggested method, and well-defined stiffener layouts are obtained. The results show that the stiffener layout is clear, and the buckling resistance performance of the optimized stiffened structures is greatly improved.

Multimaterial layout optimization of truss structures via an improved particle swarm optimization algorithm

This paper presents an extension of the basic truss layout optimization, in which the use of various materials is considered. A novel improved version of the particle swarm optimization algorithm, namely, GEMPSO, is developed for solving this problem. The enhancement is realized by introducing two core strategies: gradient estimation and multiple subpopulation division. The efficiency and reliability of the proposed improvements are demonstrated on a set of six test problems and three truss structures. Two multimaterial layout optimizations of truss structures are performed. The numerical results reveal that the appropriate partial use of expensive stronger materials can reduce the overall cost of multimaterial structures.

Layout Optimization for Blended Wing Body Aircraft Structure

Structural layout design of blended wing body (BWB) aircraft in the preliminary design phase is a challenging optimization problem due to large numbers of design variables and various constraints. A two-loop optimization strategyis proposed to solve the BWB aircraft structural layout design problem considering constraints of the displacement, stress, strain, and buckling. The two-loop optimization consists of an inner loop and an outer loop. The inner loop is to optimize each stiffened panel of the BWB aircraft structure, and outer loop is to find the best layout design. To improve computational efficiency, an equivalent finite element model is applied to BWB aircraft structure analysis, and an analytical method is used for buckling and static analysis of the stiffened panels. The proposed method can efficiently solve the structural layout optimization problem of a notional BWB aircraft with acceptable computational burden. The result indicates the mass of main load-carrying structure of the BWB aircraft is reduced by 9.28% compared to that of the initial structural layout.

Development of a Composite Model for Simulating Landscape Pattern Optimization Allocation: A Case Study in the Longquanyi District of Chengdu City, Sichuan Province, China

The simulation of landscape pattern optimization allocation (LPOA) to achieve ecological security is an important issue when constructing regional ecological security patterns. In this study, an LPOA model was developed by integrating a binary logistic regression model and a nonlinear programming model with a particle swarm optimization algorithm in order to consider the complexity of landscape pattern optimization in terms of the quantitative structure and spatial layout optimization, integrating the landscape suitability and factors that influence landscape patterns, and under constraints to maximize the economic, ecological, and comprehensive benefits of landscape patterns. The model was employed to simulate the LPOA in the Longquanyi District of Chengdu City, Sichuan Province, China. The model successfully obtained an appropriate combination of the landscape quantitative structure and spatial layout, as well as effectively integrating the landscape suitability and factors that influence the landscape pattern. Thus, the model addressed the problems of previous studies, such as neglecting the coupling between quantitative structure optimization and spatial layout optimization, ignoring the macrofactors that affect landscape patterns during optimization modeling, and initializing particles without considering the suitability of the landscape. Furthermore, we assessed and analyzed the accuracy and feasibility of the landscape pattern spatial layout optimization results, where the results showed that the overall accuracy of the optimization results was 84.98% with a Kappa coefficient of 0.7587, thereby indicating the good performance of the model. Moreover, the simulated optimization allocation scheme for the landscape pattern was consistent with the actual situation. Therefore, this model can provide support and a scientific basis for regional landscape pattern planning, land use planning, urban planning, and other related spatial planning processes.

Periodic Layout Optimization of Cyclic Symmetric Structure

This paper proposes a new optimization method to solve periodic layout optimization of a cyclic symmetric structure by means of the guide-weight method. The mathematical model for periodic layout optimization under multiple constraints is built on a single working condition. By constructing a virtual fan-shaped subdomain, periodic layout optimization of the cyclic symmetric structure is transformed into the conventional topology optimization of the virtual fan-shape subdomain. Starting from the Lagrange equation, the general iterative criterion of the virtual fan-shaped subdomain is deduced by the guide-weight method. Taking the problem of minimum compliance as an example, the iterative criterion between relative density and strain energy density of elements in the virtual fan-shaped subdomain is obtained under the condition of mass constraint. The physical significance of iterative criterion is explained and the optimization flow of periodic layout optimization is provided. Two examples of the cyclic symmetric structure show that the proposed method is effective and robust to solve the problem of periodic layout optimization.

Hypotrochoid spiral optimization approach for sizing and layout optimization of truss structures with multiple frequency constraints

The primary aim of this article is to present a new improved version of the spiral optimization algorithm (SPO) for shape and size optimization of truss structures under multiple frequency constraints. In the proposed method, which is named as hypotrochoid spiral optimization algorithm (HSPO), the movement operation of search points is redesigned, and mechanisms are utilized to boost the potency of the method in escaping from local optima and improving the accuracy of the results. Furthermore, a meta-optimization approach is developed by hybridizing the particle swarm optimization and the proposed technique for finding optimal parameter settings of the presented method. Thereafter, exploration and exploitation abilities of HSPO and SPO are compared by solving five benchmark design problems. Numerical results indicate that the convergence speed is enhanced, especially in the exploitation phase of the HSPO. The optimum designs found by the improved version are highly competitive with the best solutions reported in the literature.

An explicit optimization model for integrated layout design of planar multi-component systems using moving morphable bars

Layout design of multi-component systems has received ever-increasing attention over recent years. However, most of the current literature on the layout design of multi-component systems conducted are all carried out in an implicit way. In this paper, an explicit optimization model based on the moving morphable bars method is proposed. To this aim, topology description functions are used to describe the geometrical shapes of embedded components, while moving bars act as supporting structure that connects these embedded components. Different from traditional optimization methods, the geometric parameters used to describe the size, shape, location and orientation of the moving bars and embedded components are considered as design variables in this work. To avoid remeshing the grids and improve the efficiency of computation, the moving bars and embedding components are mapped into two density fields on a fixed grid using a smoothed Heaviside function. A discrete material interpolation scheme developed for orientation optimization problem is extended for the first time to the material parameterization of multi-component systems. Moreover, a single explicit constraint based on the volume and perimeter of embedded components is proposed for avoiding overlaps between the embedded components, and between each component and the design domain boundary. Several numerical examples are performed to show the effectiveness and flexibility of the presented optimization model in handling layout optimization of structures with multi-phase embedded components.

A modified stiffness spreading method for layout optimization of truss structures

The stiffness spreading method (SSM) was initially proposed for layout optimization of truss structures, in which an artificial elastic material of low modulus is uniformly distributed in the design domain to create connections between discrete members. In this paper, a modified stiffness spreading method is proposed by replacing the artificial elastic material with auxiliary bars to connect real members of the truss structure. Since the background continuum mesh for the elastic material is no longer required, the computational cost is significantly reduced. Like SSM, the new method is advantageous in that an initial design may consist of disconnected bars allocated in the design domain, and mathematical programming methods can be applied for the efficient solution of the formulated optimization problem. A number of solution strategies are also developed to achieve more practical designs with lower computational cost. Numerical examples of both 2-D and 3-D truss structures are presented to demonstrate the feasibility, robustness and effectiveness of the proposed method.

Topology optimization for continuous and discrete orientation design of functionally graded fiber-reinforced composite structures

This paper presents a topology optimization method for the sequential design of material layout and fiber orientation in functionally graded fiber-reinforced composite structures. Specifically, the proposed method can find the optimal structural layout of matrix and fiber materials together with optimal discrete fiber orientations. In this method, an orientation design variable in the Cartesian coordinate system is employed with a conventional density design variable. The orientation design variable controls not only the fiber orientation, but also fiber volume fraction. The fiber volume fraction control can be used to relax the orientation design problem and simultaneously design a functionally graded structural layout of fiber material. To avoid intermediate fiber orientations and achieve discrete fiber orientation design, a penalization scheme is applied to the orientation design variable. For solving the optimization problem which involves multiple design variables such as the density variable, fiber orientation variable, and target discrete orientation set, a three-step sequential optimization procedure is proposed. In this procedure, the result for each step provides the isotropic design, continuous fiber orientation design, and functionally graded discrete orientation design, respectively. To validate the effectiveness of the proposed approach, numerical examples for structural compliance minimization and compliant mechanism design are provided.