Integrating a multi-objective optimization framework into a structural design software

In this paper, we present a tool combining two software applications aimed at optimizing structural design problems of the civil engineering domain. Our approach lies in integrating an application for designing 2D and 3D bar structures, called Ebes, with the jMetal multi-objective optimization framework. The result is a software package that helps civil engineers to create bar structures which can be optimized further with multi-objective metaheuristics according to different goals, such as minimizing the structure weight and minimizing the deformation. The main features of both Ebes and jMetal are described and how they are combined together in one single tool is explained. Finally a case study to illustrate how the application works is presented.     

高性能计算在多学科大变量飞机优化设计中的应用

波音、空客等公司飞机设计中采用的先进设计手段之一是基于高性能计算的多学科、大规模设计变量优化的应用。目前我国的高性能计算在硬件方面已处于世界领先水平,但在工程应用系统方面还无法满足需求。文章介绍了以工程实际需求为导向,以高性能计算资源为辅助手段,基于飞机设计需求而开发的多学科、大变量的并行计算软件系统及计算平台,以及利用该平台实现的航空应用算例。     

Population-based optimization in structural engineering: a review

Structural engineering is focused on the safe and efficient design of infrastructure. Projects can range in size and complexity, many requiring massive amounts of materials and expensive construction and operational costs. Therefore, one of the primary objectives for structural engineers is a cost-effective design. Incorporating optimality criteria into the design procedure introduces additional complexities that result in problems that are nonlinear, nonconvex, and have a discontinuous solution space. Population-based optimization algorithms (known as metaheuristics) have been found to be very efficient approaches to these problems. Many researchers have developed and applied state-of-art metaheuristics to automate and optimize the design of real-world civil engineering problems. While there is a large body of published papers in this area, there are few comprehensive reviews that list, summarize, and categorize metaheuristic optimization in structural engineering. This paper provides an extensive survey of a wide range of metaheuristic techniques to structural engineering optimization problems. Also, information is provided on available structural engineering benchmark problems, the formulation of different objective functions, and the handling of various types of constraints. The performance of different optimization techniques is compared for many benchmark problems.

     

基于网格实现的汽轮机基础优化设计

工程优化设计往往需要进行大规模的数值计算,拥有大量闲置资源的网格环境为建立这种高性能计算平台提供了可能.但是网格资源的动态性、异构性和分布性的本质特征,阻碍了网格技术在工程应用上的普及.为了利用网格环境中大量的闲置资源来协同解决实际工程中复杂的优化设计问题,建立了一个4层结构的高性能网格计算平台,并利用Kriging近似模型,在该平台上开发了以减轻基础重量和降低基础振幅为目的的多目标汽轮机优化设计的网格算法.使用该算法,在网格平台上对两个汽轮机基础进行了优化设计,与序列线性规划方法的结果比较表明所开发的优化算法有较高的计算精度.还分析了当使用不同数量的计算节点时网格的加速情况,说明所发展的优化方法能够在网格环境中高效地运行,搭建的网格平台也适合于工程优化设计.     

Integrating a constraint-based optimization approach into the design of oil & gas structures

Currently, design optimization is widely applied in civil and mechanical engineering. Optimization strategies are used to enhance the product performance and reduce the cost, lead time and environmental impacts related to the product lifecycle. In this context, evolutionary algorithms are used for determining the optimum solution in engineering problems. The design of complex products, such as those that are engineered to order, often requires the study of subproblems. Modularization is a common practice to reduce the complexity; however, the configuration practices are difficult to be applied in engineered to order products. As a solution, the integration of the optimization tools and model-based simulations is proposed to manage the complexity. However, even when a commercial software is available to support the parameter optimization, there may exist a lack of design tools that can be integrated with the product structure of an engineered to order product. This paper describes a design optimization approach that integrates a Constraint Satisfaction Problem (CSP) tool with model-based simulations in a collaborative design context. A platform tool is developed using the .NET and MiniZinc languages. The case study is focused on the design optimization of a 700-ton steel structure. In particular, the optimization analysis considers the mechanical behavior, weight, and cost reduction.     

An object design framework for structural engineering

Object-oriented principles have introduced several useful concepts for developing complex software systems. As a result, several methodologies have been suggested for the overall design of software systems based on these concepts. Methodologies and frameworks for designing objects that are to be part of the software systems are currently lacking. This paper proposes anobject design framework andmethodology, which utilizes the object-oriented concepts, for planning, organizing and designing structural engineering design objects. Design objects in an integrated structural engineering system are complex and often related to each other in various different ways. The paper also identifies several important relationships among structural engineering design objects. These relationships serve as communication channels through wich design objects send messages to and receive responses from each other. Several examples, drawn from reinforced concrete structures, will be presented to demonstrate the object design methodology and to illustrate how the framework is effective in reducing the complexity of design objects in an integrated structural engineering system.     

A metamodel for cyber-physical systems

With the advent of the Internet of Things and Industry 4.0 concepts, cyber-physical systems in civil engineering experience an increasing impact on structural health monitoring (SHM) and control applications. Designing, optimizing, and documenting cyber-physical system on a formal basis require platform-independent and technology-independent metamodels. This study, with emphasis on communication in cyber-physical systems, presents a metamodel for describing cyber-physical systems. First, metamodeling concepts commonly used in computing in civil engineering are reviewed and possibilities and limitations of describing communication-related information are discussed. Next, communication-related properties and behavior of distributed cyber-physical systems applied for SHM and control are explained, and system components relevant to communication are specified. Then, the metamodel to formally describe cyber-physical systems is proposed and mapped into the Industry Foundation Classes (IFC), an open international standard for building information modeling (BIM). Finally, the IFC-based approach is verified using software of the official IFC certification program, and it is validated by BIM-based example modeling of a prototype cyber-physical system, which is physically implemented in the laboratory. As a result, cyber-physical systems applied for SHM and control are described and the information is stored, documented, and exchanged on the formal basis of IFC, facilitating design, optimization, and documentation of cyber-physical systems.     

Learning-based ship design optimization approach

With the development of computer applications in ship design, optimization, as a powerful approach, has been widely used in the design and analysis process. However, the running time, which often varies from several weeks to months in the current computing environment, has been a bottleneck problem for optimization applications, particularly in the structural design of ships. To speed up the optimization process and adjust the complex design environment, ship designers usually rely on their personal experience to assist the design work. However, traditional experience, which largely depends on the designer’s personal skills, often makes the design quality very sensitive to the experience and decreases the robustness of the final design. This paper proposes a new machine-learning-based ship design optimization approach, which uses machine learning as an effective tool to give direction to optimization and improves the adaptability of optimization to the dynamic design environment. The natural human learning process is introduced into the optimization procedure to improve the efficiency of the algorithm. Q-learning, as an approach of reinforcement learning, is utilized to realize the learning function in the optimization process. The multi-objective particle swarm optimization method, multi-agent system, and CAE software are used to build an integrated optimization system. A bulk carrier structural design optimization was performed as a case study to evaluate the suitability of this method for real-world application.     

Concepts and implementation of parallel finite element analysis

The design of complex engineering systems such as advanced aircraft structures and offshore platforms requires continually increasing levels of detail in supporting analysis. The finite element method is widely used as a computational method with which to model physical systems in various engineering problems. For detailed analyses of complex designs, structural models composed of several thousands of degrees of freedom are no longer uncommon. Such design activities require large order finite element and/or finite difference models and excessive computation demands in both calculation speed and information management. The computer simulation of the nonlinear dynamic response of structures and the implementation of parallel FEM systems on a high speed multiprocessor have received considerable attention in recent years. The driving forces of these activities included the reliable simulation of automotive and aircraft crash phenomena, and the increased performance of computers. Most existing major structural analysis software systems were designed 10–20 years ago and have been optimized for current sequential computers. Such systems often are not well structured to take maximum advantage of the recent and continuing revolution in parallel vector computing capabilities. These parallel vector computer architectures not only occur in the form of large supercomputers, but are now also occurring for minicomputers and even engineering workstations. To benefit from advances in parallel computers, software must be developed which takes maximum advantage of the parallel processing feature.     

Structural shape optimization integrated with CAD environment

The research work presented here is based on the concept of the integration of optimization techniques and numerical analysis with the finite element method (FEM) and computer-aided design (CAD). A microcomputer aided optimum design system, MCADS, has been developed for general structures. Certain techniques to be discussed in the paper, e.g. the semi-analytical method for design sensitivity analysis, optimization analysis modelling for shape design, application oriented user interfaces and the coupling of automated optimization and user intervention have rendered MCADS pratical and versatile in applications for engineering structures. The above techniques and an application are presented in this paper.     

A large scale parallel fluid-structure interaction computing platform for simulating structural responses to a detonation shock

Due to the intrinsic nature of multi-physics, it is prohibitively complex to design and implement a simulation software platform for study of structural responses to a detonation shock. In this article, a partitioned fluid-structure interaction computing platform is designed for parallel simulating structural responses to a detonation shock. The detonation and wave propagation are modeled in an open-source multi-component solver based on OpenFOAM and blastFoam, and the structural responses are simulated through the finite element library deal.II. To capture the interaction dynamics between the fluid and the structure, both solvers are adapted to preCICE. For improving the parallel performance of the computing platform, the inter-solver data is exchanged by peer-to-peer communications and the intermediate server in conventional multi-physics software is eliminated. Furthermore, the coupled solver with detonation support has been deployed on a computing cluster after considering the distributed data storage and load-balancing between solvers. The 3D numerical result of structural responses to a detonation shock is presented and analyzed. On 256 processor cores, the speedup ratio of the simulations for a detonation shock reach 178.0 with 5.1 million of mesh cells and the parallel efficiency achieve 69.5%. The results demonstrate good potential of massively parallel simulations. Overall, a general-purpose fluid-structure interaction software platform with detonation support is proposed by integrating open source codes. And this work has important practical significance for engineering application in fields of construction blasting, mining, and so forth.     

面向集成化CAE软件开发的SiPESC研发工作进展

针对我国自主CAE软件发展缓慢的事实,根据现代工程领域的科学研究和产品研发对CAE建模、分析和设计能力提出的需求,研发自主的面向CAE工程与科学计算集成化软件平台SiPESC（Software Integration Platform for Engineering and Scientific Computation...     

Development of software for structural analysis adapted to construction engineering applications

The paper presents the development and application of software for structural analysis adapted to construction engineering applications. The software consists of data structures, application subroutine libraries and the built-in Matlab subroutine library. For each application, the user writes an application-specific main program using the data structures and routines in the subroutine libraries. This gives the user flexibility to build a main program that is adapted to the specific needs of the current application. The software has been tested in a number of real-world projects, e.g. tunnels and bridges. The examples show that the software is a useful design tool for design work.     

An Internet-based computing platform for the boundary element method

Computers combined with the Internet are dramatically changing the engineering practices in design and analysis. More and more engineering software applications are moving to the Internet, prompted by the promising advantages, such as easy access for users everywhere with an Internet connection, easy upgrade of the software, easy control of the software. All these advantages will contribute to faster and cost-effective engineering software development and applications. Successful applications of the Internet computing depend largely on the speed of data transfer on the network. The boundary element method (BEM) has the inherent advantages over other domain-based numerical methods, because the size of the BEM model files are always considerably smaller, leading to faster data transfer on the current network. In this paper, a successful investigation in implementing the BEM on the Internet is presented. A BEM code for 2D elastostatic problems is used as the first solver in this work. A graphical-user interface (GUI) for the pre- and post-processing using Java, which provides platform-independent applications, is developed and implemented on the Internet. Demonstration problems using the developed platform clearly show the feasibility of the Internet-based computing and the potentials of this platform for future BEM development with further research.     

Topology Optimization in Aircraft and Aerospace Structures Design

Topology optimization has become an effective tool for least-weight and performance design, especially in aeronautics and aerospace engineering. The purpose of this paper is to survey recent advances of topology optimization techniques applied in aircraft and aerospace structures design. This paper firstly reviews several existing applications: (1) standard material layout design for airframe structures, (2) layout design of stiffener ribs for aircraft panels, (3) multi-component layout design for aerospace structural systems, (4) multi-fasteners design for assembled aircraft structures. Secondly, potential applications of topology optimization in dynamic responses design, shape preserving design, smart structures design, structural features design and additive manufacturing are introduced to provide a forward-looking perspective.     

Structural design using multi-objective metaheuristics. Comparative study and application to a real-world problem

Many structural design problems in the field of civil engineering are naturally multi-criteria, i.e., they have several conflicting objectives that have to be optimized simultaneously. An example is when we aim to reduce the weight of a structure while enhancing its robustness. There is no a single solution to these types of problems, but rather a set of designs representing trade-offs among the conflicting objectives. This paper focuses on the application of multi-objective metaheuristics to solve two variants of a real-world structural design problem. The goal is to compare a representative set of state-of-the-art multi-objective metaheuristic algorithms aiming to provide civil engineers with hints as to what optimization techniques to use when facing similar problems as those selected in the study presented in this paper. Accordingly, our study reveals that MOCell, a cellular genetic algorithm, provides the best overall performance, while NSGA-II, the de facto standard multi-objective metaheuristic technique, also demonstrates a competitive behavior.     

Optimal design of truss structures using parallel computing

Parallel design optimization of large structural systems calls for a multilevel approach to the optimization problem. The general optimization problem is decomposed into a number of non-interacting suboptimization problems on the first level. They are controlled from the second level through coordination variables. Thus, the solutions of the independent first-level subsystems are directed towards the overall system optimum. In the present paper, optimal design of truss structures using parallel computing technique is described. In this method, optimization of a large truss structure has been carried out by decomposing the structure into sub-domains and suboptimization tasks. Each sub-domain has independent design variables and a small number of behaviour constraints. The two-level sub-domain optimum design approach is summarized by several numerical examples with speedups and efficiencies of algorithms on message passing systems. It has been noticed that the efficiency of the algorithm for design optimization increases with the size of the structure.     

Life-cycle reliability-based optimization of civil and aerospace structures

Today, it is widely recognized that optimization methodologies should account for the stochastic nature of engineering systems and that concepts and methods of life-cycle engineering should be used to obtain a cost-effective design during a specified time horizon. The recent developments in life-cycle engineering of civil and aerospace structures based on system reliability, time-dependent reliability, life-cycle maintenance, life-cycle cost and optimization constitute an important progress. The objective of this study is to present a brief review of the life-cycle reliability-based optimization field with emphasis on civil and aerospace structures.     

领域大数据应用开发与运行平台技术研究

随着大数据技术在不同领域的快速应用,构建大数据应用系统的开发与运行一体化平台,降低大数据技术在各行各业应用普及的门槛,为面向领域的大数据应用系统的快捷开发和高效运行提供方法、工具和平台支撑,成为大数据产业发展的迫切需求。由于大数据固有的复杂性、动态性、多样性及其价值独创性,目前尚未形成系统化的大数据软件开发方法,难以满足不同领域对大数据全生命周期处理的多样化需求。大数据时代的软件工程面临的挑战,体现在互为依赖的两方面：面向大数据全生命周期的集成设计开发环境和基于软件生命周期的系统运行分析工具。本文结合特定领域的实际需求,研究面向领域的大数据应用系统开发与运行一体化平台技术,覆盖大数据生命周期（获取、清洗、集成、分析、呈现）以及软件生命周期（设计、开发、运行、优化）,形成自管理、自适应、自优化的平台化解决方案。在此基础上,开展面向装备物联网及气象民生服务的大数据示范应用,以验证平台的有效性。