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Universal Mechanism Modeling Method in Virtual Assembly Environment

Chinese Journal of Mechanical Engineering 2012年第6期25卷 1105-1114页

作者： liu jianhua ZHANG Zhixian liu Yang School of Mechanical Engineering Beijing Institute of Technology Beijing 100081 China

Motion simulation and performance analysis of mechanism are important methods for analyzing assembly quality after finishing assembly simulation in virtual assembly environment. However, most simulation systems have no function of mechanism motion simulation due to the randomicity of mechanism and lack of universal mechanism modeling method. In order to realize the simulation of any mechanism after finishing assembly simulation in a virtual environment, a new universal mechanism modeling method is presented. Two main models are contained in the mechanism model： information model and mathematical model. Firstly, the information model of mechanism is proposed to describe the data structure of mechanism which contains bottom geometry data, information of constraint, link, kinematic pair and physical data. Because the object of mechanism simulation is the assembly, which is assembled during the process of assembly simulation, the information of mechanism can be obtained automatically through mechanism automatic search method. Secondly, mathematical model of mechanism is presented. The mathematical model uses mathematical method to express the mechanism. In order to realize the automatic expression of any random mechanism, basic constraint library is presented, consequently random mechanism can be described based on the basic constraint library. Finally, two examples are introduced to validate the method in the prototype system named VAPP（Virtual Assembly Process Planning）. The validation result shows that the mechanism modeling provides a universal modeling method for mechanism motion simulation in virtual assembly environment. This research has important effect on the development both of mechanism motion simulation and virtual assembly.

关键词： virtual assembly mechanism modeling motion simulation constraint library information model mathematical model

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Review on anti-loosening methods for threaded fasteners

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Chinese Journal of Aeronautics 2022年第2期35卷 47-61页

作者： Hao GONG jianhua liu Huihua FENG School of Mechanical Engineering Beijing Institute of TechnologyBeijing 100081China

Threaded fasteners naturally tend to loosen under vibration,impact,or alternating thermal *** anti-loosening methods or strategies are widely applied for preventing loosening,including a few anti-loosening designs and anti-loosening *** this review,a variety of influencing factors that improved the anti-loosening ability and helped guide the anti-loosening designs of threaded fasteners are ***,the anti-loosening structures are classified into two categories,that is,conventional and new-style anti-loosening *** former refers to widely used structures in engineering applications,while the latter refers to novel structures not available in the *** research on the evaluation and comparison of various conventional anti-loosening structures in terms of preventing loosening is summarized in detail and the newstyle anti-loosening structures from five different aspects are also surveyed based on different structural *** the future,the effects of combined factors on loosening should be considered to achieve optimal anti-loosening *** quantitative research on the mathematical relationship between the anti-loosening performance of conventional structures and structural parameters must be ***,novel structures with excellent abilities to prevent loosening are needed,and issues of difficulties in installation and disassembly,low strength at thread,large deformation,and temperature dependence also need to be addressed.

关键词： Anti-loosening designs Anti-loosening structures Bolted joints Loosening failure Preload test

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Digital Twin Modeling Enabled Machine Tool Intelligence:A Review

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 29-54页

作者： Lei Zhang jianhua liu Cunbo Zhuang School of Mechanical Engineering Tianjin University of CommerceTianjin 300134China Laboratory of Digital Manufacturing School of Mechanical EngineeringBeijing Institute of TechnologyBeijing 10081China

Machine tools,often referred to as the“mother machines”of the manufacturing industry,are crucial in developing smart manufacturing and are increasingly becoming more *** twin technology can promote machine tool intelligence and has attracted considerable research ***,there is a lack of clear and systematic analyses on how the digital twin technology enables machine tool ***,digital twin modeling was identified as an enabling technology for machine tool intelligence based on a comparative study of the characteristics of machine tool intelligence and digital *** review then delves into state-of-the-art digital twin modelingenabled machine tool intelligence,examining it from the aspects of data-based modeling and mechanism-data dual-driven ***,it highlights three bottleneck issues facing the *** these problems,the architecture of a digital twin machine tool(DTMT)is proposed,and three key technologies are expounded in detail:Data perception and fusion technology,mechanism-data-knowledge hybrid-driven digital twin modeling and virtual-real synchronization technology,and dynamic optimization and collaborative control technology for multilevel ***,future research directions for the DTMT are *** work can provide a foundation basis for the research and implementation of digital-twin modeling-enabled machine tool intelligence,making it significant for developing intelligent machine tools.

关键词： Machine tool Digital twin Smart manufacturing Synchronization

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Unique Structure and Mechanical Property of Dabryanus Scale

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Journal of Bionic Engineering 2016年第4期13卷 641-649页

作者： Mei Yu Haoran liu jianhua liu Songmei Li School of Materials Science and Engineering Beihang University Beijing 100191 China

The structure and mechanical property of Dabryanus scale were investigated. Environmental Scanning Electron Micros- copy （ESEM） and Transmission Electron Microscopy （TEM） were used to observe the scale structure. The scale has a discrete osseous layer which is composed of boat-like unit （due to the shape）. The osseous layer is embedded into fibrillary layer, and the largest thickness ratio of osseous layer to fibrillary layer is about 7, much higher than those of other reported fish scales. Nanoindentation test was used to investigate mechanical property of the scale. Elastic modulus （E,） and hardness （H） of Dabryanus scale are much lower than those of other reported fish scales. Scale models were proposed and the principles of materials mechanics were used to analyze the mechanical properties of the Dabryanus scale. The boat-like unit in osseous layer makes the scale flexible while keeping a high thickness ratio of osseous layer to fibrillary layer, which increases the flexibility and protection capacity of the scale This study may provide new strategy for the design of flexible armor or flexible devices.

关键词： biological materials microstructures flexibility Dabryanus scale nanoindentation structure-property relationship

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Physics-based Modeling and Simulation for Motional Cable Harness Design

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Chinese Journal of Mechanical Engineering 2014年第5期27卷 1075-1082页

作者： liu jianhua ZHAO Tao NING Ruxin liu Jiashun School of Mechanical Engineering Beijing Institute of Technology

The design work of motional cable in products is vital due to the difficulty in estimating the potential issues in current *** this paper,a physics-based modeling and simulation method for the motional cable harness design is *** model,based on continuum mechanics,is established by analyzing the force of microelement in *** the analysis procedure,three coordinate systems：inertial,Frenet and main-axis coordinate systems are *** variable substitution and dimensionless processing,the equation set is discretized by differential quadrature method and subsequently becomes an overdetermined nonlinear equation set with boundary conditions solved by Levenberg-Marquardt *** the profile of motional cable harness obtained from the integral of arithmetic solution,a motion simulation system based on＂path＂and＂profile＂as well as the experimental equipments is *** the same parameters as input for the simulation and the real cable harness correspondingly,the issue in designing,such as collision,can be easily found by the simulation *** research obtains a better result which has no potential collisions by redesign,and the proposed method can be used as an accurate and efficient way in motional cable harness design work.

关键词： motional cable harness physics-based modeling motion simulation Kirchhoff rod

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Effect of sulphate-reducing bacteria on the electrochemical impedance spectroscopy characteristics of 1Cr18Ni9Ti

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Journal of University of Science and Technology Beijing 2007年第5期14卷 425-430页

作者： jianhua liu Xin Liang Songmei Li School of Materials Science and Engineering Beihang University Beijing 100083 China

The electrochemical characteristics of 1Cr18Ni9Ti in sulphate-reducing bacteria （SRB） solutions and the biofilm of SRB on the surface of the 1Cr18Ni9Ti electrode were studied by electrochemical, microbiological, and surface analysis methods. Electrochemical impedance spectroscopy （EIS） of 1Cr18Ni9Ti was measured in the solutions with and without SRB at the culture time of 2, 4, 8 d, respectively. The measurement used two test methods, the nonimmersion electrode method and the immersion electrode method. It was found that the polarization resistance （Rp） of 1Cr18Ni9Ti in the solutions without SRB is the greatest for each test method. When using the nonimmersion electrode method, Rp shifts negatively at first and then positively, and the time constant is only one. Although using the immersion electrode method, the Rp shifts positively at first and then negatively, and the time constant also changes when the biofilm forms. The biofilm observed through SEM is with pores. It was demonstrated that SRB has accelerated corrosion action on 1Cr18Ni9Ti. The protection effect of the biofilm on the electrode depends on the compact degree of the film.

关键词： stainless steel biofilm microbiologically induced corrosion (MIC) EIS (electrochemical impedance spectroscopy)

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Kinematics Analysis of Mechanisms Based on Virtual Assembly

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Chinese Journal of Mechanical Engineering 2010年第6期23卷 748-757页

作者： ZHANG Zhixian liu jianhua NING Ruxin School of Mechanical Engineering Beijing Institute of Technology Beijing 100081 China

Currently, virtual assembly technology has attracted increasing attention due to considerations of solving assembly problems in virtual environment before actual assembly in manufactory. Previous studies on kinematic analysis of mechanism only aim at analyzing motion law of single mechanism, but can not simulate the multi-mechanisms motion process at the same time, let alone simulating the automatic assembly process of products in a whole assembly workshop. In order to simulate the assembly process of products in an assembly workshop and provide effective data for analyzing mechanical performance after finishing assembly simulation in virtual environment, this study investigates the kinematics analysis of mechanisms based on virtual assembly. Firstly, in view of the same function of the kinematic pairs and the assembly constraints on restricting the motion of components （subassembly or part）, the method of identifying kinematic pairs automatically based on assembly constraints is presented. The information of kinematic pairs can be obtained through calculating the constraint degree of the assembly constraints. Secondly, the incidence matrix eliminating element method is proposed in order to search the information and establish the models of mechanisms automatically after finishing assembly simulation in virtual environment. Both methods have important significance for reducing the workload of pretreatment and promoting the level of automation of kinematics analysis. Finally, the method of kinematics analysis of mechanisms is presented. Based on Descartes coordinates, three types of kinematics equations are formed. The parameters, like displacement, velocity, and acceleration, can be obtained by solving these equations. All these data are important to analyze mechanical performance. All the methods are implemented and validated in the prototype system virtual assembly process planning（VAPP）. The mechanism models are established and simulated in the VAPP system, and t

关键词： virtual assembly assembly constraint constraint degree eliminating element method kinematics equations,kinematics analysis

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Corrosion behavior of a CuCrNiAl alloy in the presence of NaCl deposit

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Rare Metals 2006年第3期25卷 210-215页

作者： XU Tao CHANG Limin liu jianhua Department of Applied Technology Daqing Petroleum Institute Daqing 163318 China Analysis and Measure Center Jilin Normal University Siping 136000 China Key Laboratory of Metastable Materials Science and Technology Yanshan University Qinhuangdao 066004 China

The corrosion behavior of a CuCrNiAl alloy with NaCl deposit at 700 and 900℃ was studied by means of metalloscope, XRD, SEM/EDX, and thermogravimetric analysis. The results indicated that the corrosion of the CuCrNiAl alloy beneath the NaCl deposit is severe; the corrosion production is loose and easy to scale off; the Cr phase is easier to erode than the Cu phase, and the contents of Cu and Cr decrease when the content of Ni increases in the matrix of the alloy beneath the corrosion region. The effects of distortion on the corrosion of the CuCrNiAl alloy were discussed, and the acceleration mechanisms of NaCl on the corrosion were also discussed.

关键词： CuCrNiAl alloy corrosion NaCl high temperature

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Computational Path Planner for Product Assembly in Complex Environments

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Chinese Journal of Mechanical Engineering 2013年第2期26卷 282-292页

作者： SHANG Wei liu jianhua NING Ruxin liu Mi School of Mechanical Engineering Beijing Institute of Technology

Assembly path planning is a crucial problem in assembly related design and manufacturing processes. Sampling based motion planning algorithms are used for computational assembly path planning. However, the performance of such algorithms may degrade much in environments with complex product structure, narrow passages or other challenging scenarios. A computational path planner for automatic assembly path planning in complex 3D environments is presented. The global planning process is divided into three phases based on the environment and specific algorithms are proposed and utilized in each phase to solve the challenging issues. A novel ray test based stochastic collision detection method is proposed to evaluate the intersection between two polyhedral objects. This method avoids fake collisions in conventional methods and degrades the geometric constraint when a part has to be removed with surface contact with other parts. A refined history based rapidly-exploring random tree （RRT） algorithm which bias the growth of the tree based on its planning history is proposed and employed in the planning phase where the path is simple but the space is highly constrained. A novel adaptive RRT algorithm is developed for the path planning problem with challenging scenarios and uncertain environment. With extending values assigned on each tree node and extending schemes applied, the tree can adapts its growth to explore complex environments more efficiently. Experiments on the key algorithms are carried out and comparisons are made between the conventional path planning algorithms and the presented ones. The comparing results show that based on the proposed algorithms, the path planner can compute assembly path in challenging complex environments more efficiently and with higher success. This research provides the references to the study of computational assembly path planning under complex environments.

关键词： assembly path planning motion planning stochastic collision detection rapidly-exploring random tree adaptive RRT

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黄河下游豫鲁地区创新网络时空演化及环境效应研究

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河南师范大学学报（自然科学版） 2025年第1期53卷 1-12,F0002页

作者：刘建华赵鼎葛世帅黄亮朝崔源郑州大学管理学院郑州450001 郑州大学黄河生态保护与区域协调发展研究院郑州450001 河南交通职业技术学院交通信息工程系郑州450000

创新是城市与区域发展的核心动力,创新网络是提升区域创新能力的重要支撑.以黄河下游豫鲁地区为研究对象,采用修正后的引力模型来构建城市间的创新关联网络,运用社会网络分析法探究2014-2022年空间关联网络的演化与特征,并探析黄河下游... 详细信息

创新是城市与区域发展的核心动力,创新网络是提升区域创新能力的重要支撑.以黄河下游豫鲁地区为研究对象,采用修正后的引力模型来构建城市间的创新关联网络,运用社会网络分析法探究2014-2022年空间关联网络的演化与特征,并探析黄河下游豫鲁地区创新网络对环境的影响.研究发现,整体来看,黄河下游豫鲁地区整体创新网络发展水平逐步提高,但空间分布不均的特征明显,创新网络整体发展水平仍处于起步阶段;分区域来看,河南省创新网络水平存在严重的两极分化现象,在空间上呈“米”字形分布.山东省整体创新网络水平高于河南省,创新资源分布较为均衡;研究期内,郑州、济南、青岛等城市是网络中的溢出主体,其中郑州、青岛是网络中的关键节点,影响整个网络稳定性.此外,研究区凝聚子群呈现出以郑州、济南、青岛为引领的“三核心”创新网络格局,但子群倾向于“抱团”,行政壁垒尚未消除;黄河下游豫鲁地区创新网络与环境污染呈倒“U”型关系,当创新网络水平跨过“拐点”时,才会对环境污染产生抑制作用,从而有效改善环境质量.在创新网络发展初期,开放程度、经济水平和人口规模扩大会加剧环境污染程度,而环境治理支出的增长和产业结构的优化能有效抑制环境污染.

关键词：黄河下游豫鲁地区空间联系网络引力模型社会网络分析环境污染

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