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A MATLAB code for the material-field series-expansion topology optimization method

《机械工程前沿(英文)》 2021年 第16卷 第3期   页码 607-622 doi: 10.1007/s11465-021-0637-3

摘要: This paper presents a MATLAB implementation of the material-field series-expansion (MFSE) topo-logy optimization method. The MFSE method uses a bounded material field with specified spatial correlation to represent the structural topology. With the series-expansion method for bounded fields, this material field is described with the characteristic base functions and the corresponding coefficients. Compared with the conventional density-based method, the MFSE method decouples the topological description and the finite element discretization, and greatly reduces the number of design variables after dimensionality reduction. Other features of this method include inherent control on structural topological complexity, crisp structural boundary description, mesh independence, and being free from the checkerboard pattern. With the focus on the implementation of the MFSE method, the present MATLAB code uses the maximum stiffness optimization problems solved with a gradient-based optimizer as examples. The MATLAB code consists of three parts, namely, the main program and two subroutines (one for aggregating the optimization constraints and the other about the method of moving asymptotes optimizer). The implementation of the code and its extensions to topology optimization problems with multiple load cases and passive elements are discussed in detail. The code is intended for researchers who are interested in this method and want to get started with it quickly. It can also be used as a basis for handling complex engineering optimization problems by combining the MFSE topology optimization method with non-gradient optimization algorithms without sensitivity information because only a few design variables are required to describe relatively complex structural topology and smooth structural boundaries using the MFSE method.

关键词: MATLAB implementation     topology optimization     material-field series-expansion method     bounded material field     dimensionality reduction    

optimization of hinge-free compliant mechanisms with material uncertainties based on a non-probabilistic field

Junjie ZHAN, Yangjun LUO

《机械工程前沿(英文)》 2019年 第14卷 第2期   页码 201-212 doi: 10.1007/s11465-019-0529-y

摘要: This paper presents a new robust topology optimization framework for hinge-free compliant mechanisms with spatially varying material uncertainties, which are described using a non-probabilistic bounded field model. Bounded field uncertainties are efficiently represented by a reduced set of uncertain-but-bounded coefficients on the basis of the series expansion method. Robust topology optimization of compliant mechanisms is then defined to minimize the variation in output displacement under constraints of the mean displacement and predefined material volume. The nest optimization problem is solved using a gradient-based optimization algorithm. Numerical examples are presented to illustrate the effectiveness of the proposed method for circumventing hinges in topology optimization of compliant mechanisms.

关键词: compliant mechanisms     robust topology optimization     hinges     uncertainty     bounded field    

Multi-UAV cooperative target tracking with bounded noise for connectivity preservation

Rui Zhou, Yu Feng, Bin Di, Jiang Zhao, Yan Hu,jzhao@buaa.edu.cn

《信息与电子工程前沿(英文)》 2020年 第21卷 第10期   页码 1413-1534 doi: 10.1631/FITEE.1900617

摘要: We investigate cooperative target tracking of multiple unmanned aerial vehicles (UAVs) with a limited communication range. This is an integration of UAV motion control, target state estimation, and network topology control. We first present the communication topology and basic notations for , and introduce the distributed . Then, convergence and boundedness of the estimation errors using the filter are analyzed, and potential functions are proposed for communication link maintenance and collision avoidance. By taking stable target tracking into account, a distributed potential function based UAV motion controller is discussed. Since only the estimation of the target state rather than the state itself is available for UAV motion control and UAV motion can also affect the accuracy of state estimation, it is clear that the UAV motion control and target state estimation are coupled. Finally, the stability and convergence properties of the coupled system under are analyzed in detail and demonstrated by simulations.

Robust cooperation of connected vehicle systems with eigenvalue-bounded interaction topologies in the

Keqiang LI, Feng GAO, Shengbo Eben LI, Yang ZHENG, Hongbo GAO

《机械工程前沿(英文)》 2018年 第13卷 第3期   页码 354-367 doi: 10.1007/s11465-018-0486-x

摘要:

This study presents a distributed H-infinity control method for uncertain platoons with dimensionally and structurally unknown interaction topologies provided that the associated topological eigenvalues are bounded by a predesigned range. With an inverse model to compensate for nonlinear powertrain dynamics, vehicles in a platoon are modeled by third-order uncertain systems with bounded disturbances. On the basis of the eigenvalue decomposition of topological matrices, we convert the platoon system to a norm-bounded uncertain part and a diagonally structured certain part by applying linear transformation. We then use a common Lyapunov method to design a distributed H-infinity controller. Numerically, two linear matrix inequalities corresponding to the minimum and maximum eigenvalues should be solved. The resulting controller can tolerate interaction topologies with eigenvalues located in a certain range. The proposed method can also ensure robustness performance and disturbance attenuation ability for the closed-loop platoon system. Hardware-in-the-loop tests are performed to validate the effectiveness of our method.

关键词: automated vehicles     platoon     distributed control     robustness    

Recent progress in electric-field assisted combustion: a brief review

《能源前沿(英文)》 2022年 第16卷 第6期   页码 883-899 doi: 10.1007/s11708-021-0770-z

摘要: The control of combustion is a hot and classical topic. Among the combustion technologies, electric-field assisted combustion is an advanced techno-logy that enjoys major advantages such as fast response and low power consumption compared with thermal power. However, its fundamental principle and impacts on the flames are complicated due to the coupling between physics, chemistry, and electromagnetics. In the last two decades, tremendous efforts have been made to understand electric-field assisted combustion. New observations have been reported based on different combustion systems and improved diagnostics. The main impacts, including flame stabilization, emission reduction, and flame propagation, have been revealed by both simulative and experimental studies. These findings significantly facilitate the application of electric-field assisted combustion. This brief review is intended to provide a comprehensive overview of the recent progress of this combustion technology and further point out research opportunities worth investigation.

关键词: electric field     combustion     flame stabilization     emission reduction     flame propagation    

Field test on temperature field and thermal stress for prestressed concrete box-girder bridge

Baoguo CHEN, Rui DING, Junjie ZHENG, Shibiao ZHANG

《结构与土木工程前沿(英文)》 2009年 第3卷 第2期   页码 158-164 doi: 10.1007/s11709-009-0002-9

摘要: A field test was conducted to investigate the distribution of temperature field and the variation of thermal stress for a prestressed concrete (PC) box-girder bridge. The change of hydration heat temperature consists of four periods: temperature rising period, constant temperature period, rapid temperature fall period and slow temperature fall period. The peak value of hydration heat temperature increases with the increasing casting temperature of concrete; the relation between them is approximately linear. According to field tests, the thermal stress incurred by hydration heat may induce temperature cracks on the PC box-girder. Furthermore, the nonlinear distribution of temperature gradient and the fluctuation of thermal stress induced by exposure to sunlight were also obtained based on continuous in-situ monitoring. Such results show that the prevailing Chinese Code (2004) is insufficient since it does not take into account the temperature gradient of the bottom slab. Finally, some preventive measures against temperature cracks were proposed based on related studies. The conclusions can provide valuable reference for the design and construction of PC box-girder bridges.

关键词: box-girder bridge     field test     hydration heat     temperature field     temperature gradient     thermal stress    

Energy field-assisted high-speed dry milling green machining technology for difficult-to-machine metal

《机械工程前沿(英文)》 2023年 第18卷 第2期 doi: 10.1007/s11465-022-0744-9

摘要: Energy field-assisted machining technology has the potential to overcome the limitations of machining difficult-to-machine metal materials, such as poor machinability, low cutting efficiency, and high energy consumption. High-speed dry milling has emerged as a typical green processing technology due to its high processing efficiency and avoidance of cutting fluids. However, the lack of necessary cooling and lubrication in high-speed dry milling makes it difficult to meet the continuous milling requirements for difficult-to-machine metal materials. The introduction of advanced energy-field-assisted green processing technology can improve the machinability of such metallic materials and achieve efficient precision manufacturing, making it a focus of academic and industrial research. In this review, the characteristics and limitations of high-speed dry milling of difficult-to-machine metal materials, including titanium alloys, nickel-based alloys, and high-strength steel, are systematically explored. The laser energy field, ultrasonic energy field, and cryogenic minimum quantity lubrication energy fields are introduced. By analyzing the effects of changing the energy field and cutting parameters on tool wear, chip morphology, cutting force, temperature, and surface quality of the workpiece during milling, the superiority of energy-field-assisted milling of difficult-to-machine metal materials is demonstrated. Finally, the shortcomings and technical challenges of energy-field-assisted milling are summarized in detail, providing feasible ideas for realizing multi-energy field collaborative green machining of difficult-to-machine metal materials in the future.

关键词: difficult-to-machine metal material     green machining     high-speed dry milling     laser energy field-assisted milling     ultrasonic energy field-assisted milling     cryogenic minimum quantity lubrication energy field-assisted milling    

Temperature field simulation of laser homogenizing equipment

Juanjuan WANG, Yunshan WANG, Fudong ZHU

《机械工程前沿(英文)》 2009年 第4卷 第1期   页码 49-52 doi: 10.1007/s11465-009-0005-1

摘要: The laser homogenizing equipment was devised using the ring scanning principle. Its working principle is explained. A laser scanning ring facula is obtained when the laser beam goes through the equipment’s optical system rotating with high-frequency. The scanning ring facula’s mathematic model is established based on the temperature field’s superposing principle. The ring facula’s light intensity distribution and temperature distribution characteristics are achieved by simulating its temperature field. By studying the effect of parameters on the temperature field, the best parameter can be found. Results show that favorable temperature distribution characteristics can be attained by choosing appropriate parameters, and even the thermal effect can be realized by utilizing the circumference power compensating for the heat exchange lost in the horizontal direction. The uniform hardness layer and better process quality can be attained using the ring facula optimized for metal laser heat treatment.

关键词: laser homogenizing technology     laser scanning ring facula     temperature field    

Sulige Gas Field super project

Wenrui HU, Jingwei BAO, Pengcheng JI

《工程管理前沿(英文)》 2017年 第4卷 第3期   页码 379-384 doi: 10.15302/J-FEM-2017107

面向E级高性能计算存储墙问题研究 Article

Wei HU,Guang-ming LIU,Qiong LI,Yan-huang JIANG,Gui-lin CAI

《信息与电子工程前沿(英文)》 2016年 第17卷 第11期   页码 1154-1175 doi: 10.1631/FITEE.1601336

摘要: I/O性能与计算性能的不匹配是超级计算机从P级向E级发展的主要障碍之一。当前,I/O密集型应用迅速增加,其运行效率受到了I/O性能的制约。为进一步量化I/O性能瓶颈,分析其对大规模并行应用可扩展性的重要影响,本文在定义和分析存储受限加速比的基础上,第一次从并行应用可扩展性的角度提出"存储墙"的定义,量化和讨论了"存储墙"的存在性,并基于存储墙特性对现有高性能计算系统结构提出了新的分类方法和可扩展性分析方法。通过基于"天河1A"超级计算机的实验和基于"美洲虎"超级计算机的案例分析,本文验证了存储墙的存在性并分析了其变化特性。这些实验和分析结果对缓解和消除未来高性能计算机的存储墙瓶颈,实现平衡的软硬件设计具有重要指导意义。

关键词: 存储受限加速比;存储墙;高性能计算;E级计算    

A FEniCS implementation of the phase field method for quasi-static brittle fracture

HIRSHIKESH, Sundararajan NATARAJAN, Ratna Kumar ANNABATTULA

《结构与土木工程前沿(英文)》 2019年 第13卷 第2期   页码 380-396 doi: 10.1007/s11709-018-0471-9

摘要: In the recent years, the phase field method for simulating fracture problems has received considerable attention. This is due to the salient features of the method: 1) it can be incorporated into any conventional finite element software; 2) has a scalar damage variable is used to represent the discontinuous surface implicitly and 3) the crack initiation and subsequent propagation and branching are treated with less complexity. Within this framework, the linear momentum equations are coupled with the diffusion type equation, which describes the evolution of the damage variable. The coupled nonlinear system of partial differential equations are solved in a ‘staggered’ approach. The present work discusses the implementation of the phase field method for brittle fracture within the open-source finite element software, FEniCS. The FEniCS provides a framework for the automated solutions of the partial differential equations. The details of the implementation which forms the core of the analysis are presented. The implementation is validated by solving a few benchmark problems and comparing the results with the open literature.

关键词: phase field method     FEniCS     brittle fracture     crack propagation     variational theory of fracture    

Centrifuge model test and field measurement analysis for foundation pit with confined water

Chunlin DING , Xiaohong MENG ,

《结构与土木工程前沿(英文)》 2009年 第3卷 第3期   页码 299-304 doi: 10.1007/s11709-009-0035-0

摘要: The similarity law of centrifuge test was developed for the seepage field and stress field of a foundation pit with confined water by analyzing control equations, and a similarity index and a similarity coefficient of centrifuge test were obtained. Based on the deep foundation pit of the Huangxing Road Station of the Shanghai metro line M8, the deformation stability of the pit was tested. Finally, a comparative study was conducted on the test results of the pit deformation and the field measurement results. Comparison results show that the pit deformation regularity of the test is basically identical with that of the field measurement, and the difference in pit deformation between the test and the field measurement is within 50%. The centrifuge model test can effectively simulate the displacement response of the ground and retaining structure during dewatering and excavation for the pit with confined water, which provides a reliable basis for the design and construction of the pit with confined water.

关键词: foundation pit with confined water     centrifuge model test     seepage-stress coupling field     similarity relation     field measurement     deformation    

Study on the measurement of temperature field using laser holographic interferometry

Jinrong ZHU, Suyi HUANG, Wei LV, Huaichun ZHOU

《能源前沿(英文)》 2011年 第5卷 第1期   页码 120-124 doi: 10.1007/s11708-010-0107-9

摘要: The temperature field of an axisymmetric ethylene diffusion flame is measured using laser holographic interferometry. Temperature field inversion is completed with the aid of components distribution divided from numerical simulation of combustion and air components assumption. Error analysis of key steps is conducted using the theoretical formula of interference temperature measurement and characteristic structure of fringes obtained from optical simulation. Based on the calculation and analysis, air components assumption will not cause significant error in the low temperature region but will result in high error in the high temperature region. Moreover, the small error in environmental temperature measurement transfer to a high temperature range will expand more than tenfold. Results of temperature measurement using air components assumption relative to combustion simulation require the greatest amendment amounting to seven percent.

关键词: temperature field     flame     error analysis     holographic interferometry    

Implementation aspects of a phase-field approach for brittle fracture

G. D. HUYNH, X. ZHUANG, H. NGUYEN-XUAN

《结构与土木工程前沿(英文)》 2019年 第13卷 第2期   页码 417-428 doi: 10.1007/s11709-018-0477-3

摘要: This paper provides a comprehensive overview of a phase-field model of fracture in solid mechanics setting. We start reviewing the potential energy governing the whole process of fracture including crack initiation, branching or merging. Then, a discretization of system of equation is derived, in which the key aspect is that for the correctness of fracture phenomena, a split into tensile and compressive terms of the strain energy is performed, which allows crack to occur in tension, not in compression. For numerical analysis, standard finite element shape functions are used for both primary fields including displacements and phase field. A staggered scheme which solves the two fields of the problem separately is utilized for solution step and illustrated with a segment of Python code.

关键词: phase-field modeling     FEM     staggered scheme     fracture    

Design and analysis of linear oscillating motor for linear pump application-magnetic field, dynamics

Zongxia JIAO,Tianyi WANG,Liang YAN

《机械工程前沿(英文)》 2016年 第11卷 第4期   页码 351-362 doi: 10.1007/s11465-016-0407-9

摘要:

A linear oscillating motor is an electromagnetic actuator that can achieve short-stroke reciprocating movement directly without auxiliary transmission mechanisms. It has been widely used in linear pump applications as the source of power and motion. However, because of the demand of high power density in a linear actuation system, the performance of linear oscillating motors has been the focus of studies and deserves further research for high power density. In this paper, a general framework of linear oscillating motor design and optimization is addressed in detail, including the electromagnetic, dynamics, and thermal aspects. First, the electromagnetic and dynamics characteristics are modeled to reveal the principle for optimization. Then, optimization and analysis on magnetic structure, resonant system, and thermal features are conducted, which provide the foundation for prototype development. Finally, experimental results are provided for validation. As a whole, this process offers complete guidance for high power density linear oscillating motors in linear pump applications.

关键词: linear oscillating motor     linear pump     magnetic field     motor optimization    

标题 作者 时间 类型 操作

A MATLAB code for the material-field series-expansion topology optimization method

期刊论文

optimization of hinge-free compliant mechanisms with material uncertainties based on a non-probabilistic field

Junjie ZHAN, Yangjun LUO

期刊论文

Multi-UAV cooperative target tracking with bounded noise for connectivity preservation

Rui Zhou, Yu Feng, Bin Di, Jiang Zhao, Yan Hu,jzhao@buaa.edu.cn

期刊论文

Robust cooperation of connected vehicle systems with eigenvalue-bounded interaction topologies in the

Keqiang LI, Feng GAO, Shengbo Eben LI, Yang ZHENG, Hongbo GAO

期刊论文

Recent progress in electric-field assisted combustion: a brief review

期刊论文

Field test on temperature field and thermal stress for prestressed concrete box-girder bridge

Baoguo CHEN, Rui DING, Junjie ZHENG, Shibiao ZHANG

期刊论文

Energy field-assisted high-speed dry milling green machining technology for difficult-to-machine metal

期刊论文

Temperature field simulation of laser homogenizing equipment

Juanjuan WANG, Yunshan WANG, Fudong ZHU

期刊论文

Sulige Gas Field super project

Wenrui HU, Jingwei BAO, Pengcheng JI

期刊论文

面向E级高性能计算存储墙问题研究

Wei HU,Guang-ming LIU,Qiong LI,Yan-huang JIANG,Gui-lin CAI

期刊论文

A FEniCS implementation of the phase field method for quasi-static brittle fracture

HIRSHIKESH, Sundararajan NATARAJAN, Ratna Kumar ANNABATTULA

期刊论文

Centrifuge model test and field measurement analysis for foundation pit with confined water

Chunlin DING , Xiaohong MENG ,

期刊论文

Study on the measurement of temperature field using laser holographic interferometry

Jinrong ZHU, Suyi HUANG, Wei LV, Huaichun ZHOU

期刊论文

Implementation aspects of a phase-field approach for brittle fracture

G. D. HUYNH, X. ZHUANG, H. NGUYEN-XUAN

期刊论文

Design and analysis of linear oscillating motor for linear pump application-magnetic field, dynamics

Zongxia JIAO,Tianyi WANG,Liang YAN

期刊论文