In order to obtain the optimal PVDF piezoelectric fiber film to enhance its piezoelectric properties, PVDF was used as solute, N–N dimethylformamide (DMF) and acetone were used as solvents, and the electrospinning process parameters and electrode corona were optimized. Based on the control variable method, the effects of solvent ratio (volume ratio of DMF to acetone), solution concentration, spinning voltage, solution injection speed and receiving drum speed on the performance of PVDF piezoelectric fiber membrane were studied and analyzed. The characterization results of the viscosity of PVDF solution, the microstructure of PVDF piezoelectric fiber membrane, the content of crystal phase, the piezoelectric constant, the tensile strength and the dielectric constant after silver electrode were measured. The optimal preparation process parameters of PVDF piezoelectric membrane were obtained: solvent ratio 6:4, solution concentration 15

The theory of the radial deformation generated by the assembly of the flexwheel and the wave generator of the cup harmonic reducer is inconsistent with the practice, and the tooth meshing interferes between the flexwheel and the rigid wheel. Based on the deformation of the flexwheel assembly, a method for modifying the tooth profile of the flexwheel was put forward, and the appropriate modification amount was determined through the finite element assembly simulation. After the modification, the flexwheel was assembled and run through the finite element analysis. Finally, based on the Miner linear fatigue theory, the Fe-safe software was used to predict the life of flexwheels. The results show that the maximum stress during the assembly of the flexwheel is reduced from 962.2 MPa to 532.7 MPa, the stress during load operation is 609.9 MPa, the tooth stress is greatly improved, the meshing interference is solved, and the life cycle of the flexwheel is 4.28×106 times.

Based on the working conditions of the variable center distance non-circular gear pair, this research provides the rounding theories and methods for the theoretical pitch curves of the gear pair, including establish the working conditions model of the variable center distance non-circular gear pair; group and classify the instantaneous working conditions and the instantaneous meshing arcs; design rounding algorithms for instantaneous meshing arc group category 1, 2, and 3; and propose the dynamic allocation strategy for distribute the total rounding amount on each pair of instantaneous meshing arcs. Finally, with the help of a variable center distance non-circular gear pair example, this research successfully proved the correctness and effectiveness of the above rounding theory and method, achieve the goal of rounding the theoretical pitch curves of the variable center distance non-circular gear pair.

基于Ansys Workbench软件对柔性轴承建立多体接触以及动力学模型,分析了其内外圈在装配及外载荷条件下的应力应变;并基于nCode-Designlife软件,对柔性轴承内外圈进行了疲劳寿命评估.此外,针对影响柔性轴承力学特性的3个因素设计正交试验,分析了其对柔性轴承力学性能的影响.结果表明,内圈的疲劳薄弱位置位于长轴外端面,外圈的疲劳薄弱位置则位于长轴处滚珠与沟道接触区域,且最大径向变形量对内外圈的应力影响显著;在一定范围内减小径向变形并控制滚珠数,有助于减小应力提高寿命.该研究结果为柔性轴承的设计提供了参考.

Objective Aiming at the problem that the assembly quality of interference fit components is difficult to control, a method for monitoring the assembly quality of such components based on digital twin technology is proposed.Methods Combined with digital twin technology, the framework of an assembly quality monitoring system for interference fit components is constructed; the actual assembly process is comprehensively analyzed and a real-time monitoring process of the assembly process based on the press-fitting force is designed; and a state prediction model of the press-fitting force based on the Markov model is established, and a comprehensive judgment of the assembly quality of the interference fit components is realized by the comprehensive comparison of theoretical press-fitting force, actual press-fitting force and press-fitting force prediction state.Results The interference fit between the output shaft and sun gear of a typical marine planetary reducer is used as an example for verification. The results show that this method can realize the real-time collection and monitoring of the press-fitting force at key points in the assembly process and predict the future quality characteristics of the point. At the same time, the experimental results of the physical assembly platform are compared with the model prediction results, and it is found that the two are consistent, which proves that the proposed method of monitoring the assembly quality of interference fit components based on digital twin technology is effective and feasible.ConclusionThe results of this study have important reference significance for the realization of quality monitoring in the process of the intelligent assembly of mechanical products.

波发生器的形状直接影响柔轮的受力特性。柔轮是谐波减速器中最薄弱的部分，为提高其寿命，介绍了一种基于圆锥曲线组合的凸轮波发生器的设计。组合曲线凸轮波发生器轮廓由抛物线、连接圆弧和偏心圆弧组合而成；将抛物线与连接圆弧、连接圆弧与偏心圆弧平滑过渡作为约束条件，通过正交实验确定组合曲线凸轮波发生器各段曲线参数，分析了各参数对柔轮最大等效应力的影响程度；利用有限元软件，分别对标准椭圆凸轮和组合曲线式凸轮作用下的柔轮进行了瞬态动力学分析，并基于分析结果，利用nCode-Designlife软件，对柔轮的疲劳寿命进行了研究。结果表明，组合曲线凸轮波发生器作用下的柔轮最大等效应力比标准椭圆凸轮波发生器作用下的低；组合曲线凸轮波发生器作用下的柔轮啮合区的齿圈前后端应力明显降低，应力分布更加均匀，疲劳寿命也有所提高。

在结构光三维测量系统中,激光中心线提取误差是测量系统的主要误差之一.针对传统灰度重心法存在的精度不足问题,提出一种自适应卷积的激光条纹中心线提取方法.首先基于灰度重心法获取初始中心点,然后利用相邻初始中心点获取光条方向,设计卷积模板分段调整灰度分布,最后沿着法向方向提取中心的亚像素坐标.实验结果显示,以Steger法作为评价标准,所提方法的均方根误差最低,优于其他几种改进的灰度重心算法,单幅激光图像提取速度为0.116 s,并且稳定性好.

柔轮作为谐波减速器中最薄弱的环节之一,一直是谐波减速器可靠性研究中备受关注的对象.以CSG-32-80型谐波减速器为对象,利用Ansys Workbench对其柔轮进行了瞬态分析,得出了柔轮应力、应变的分布情况;将有限元分析结果导入Ncode Designlife疲劳分析模块,结合柔轮材料的S-N应力—寿命曲线,得出了柔轮的疲劳寿命.并通过正交实验的方式探究了柔轮最大应力与柔轮长度、柔轮壁厚、柔轮齿宽3种参数之间的关系,为柔轮结构的最优化设计提供了一定理论参考.

现如今,随着我国经济的快速发展,在当前社会快速发展的背景下,我国建筑行业有着广阔的发展空间,并在市场中占据了优势地位.但是不可否认,各建筑行业在发展中依然存在各种问题有待完善,其中主要体现在建筑施工技术方面.在建筑施工过程中应用防水防渗施工技术,会显著提升整体建筑质量和使用性能.如果在建筑施工过程中未能科学采用防水防渗施工技术,不仅会导致建筑施工质量不合格,影响使用年限,同时还会影响人们的生命财产安全,所以要求在建筑施工中及时改变传统的技术手段,提升施工工作者的防渗漏意识,在各项工作环节中始终关注渗漏现象,以此在根源处处理渗漏现象.

现如今，随着我国经济的快速发展，有效加快了我国建筑工程行业的发展速度。目前，我国正在积极建设环保型社会，人们的绿色环保意识越来越为深入，在此背景下，我国建筑工程领域中研发出了一种新型建筑模式，即装配式建筑，因为装配式建筑比传统建筑工程具有很多优势特点，有助于绿色环保型社会的构建，所以装配式建筑在我国建筑行业中得到越来越为广泛的应用。基于此，本文首先对装配式建筑进行了简单概述，然后比较分析了传统混凝土建筑与装配式建筑二者之间的优劣势，然后对装配式建筑结构施工技术要点进行了深入研究，具有重要意义。

为提高数字孪生车间系统运行过程中映射关系的忠实性与实时性,提出一种逻辑与模型数据并行计算的数字孪生车间系统快速架构方法。采用车间物理信息建模的方式描述模型和逻辑信息并搭建数字孪生车间的构建规则,分别对系统静态模型数据和动态逻辑数据进行建模分析,将静态模型顶点、面片等数据作为数组发送至GPU常量缓存区,在缓存区中通过矩阵转换预设静态孪生模型在虚拟空间中的位置变换,通过GPU常量缓存区和预置变换对静态模型数据进行并行处理,提升计算效率。验证结果表明,在相同的工艺逻辑数据和模型数量条件下,所提出的孪生系统架构方法可以将GPU使用效率由43%提升至86%,运行帧数由22.6提升至387.0,大幅提升数字孪生系统的执行效率和性能。

为了降低谐波减速器柔轮装配变形后的倾角的影响,以传统的余弦波发生器为研究对象提出一种轴向带有0.98°倾角的三维波发生器。设计基于包络理论法的双圆弧公切线齿廓,并进行谐波传动平面运动学分析。通过Abaqus软件对柔轮与波发生器装配过程的有限元分析,得到柔轮的装配变形、应力分布情况。与余弦波发生器装配结果对比发现,采用带有倾角的三维波发生器装配使柔轮长轴处径向变形量更接近理论值0.35mm,柔轮最大应力从865.7 MPa降低至682.3MPa,显著降低柔轮装配应力,使柔轮后端面与筒体连接处应力分布更加均匀。圆周方向0°～180°应力值保持在24.4～176.172MPa。

基于ANSYS有限元仿真数据,采用包络法对谐波减速器的刚、柔轮共轭齿廓进行设计和初步优化.在对刚轮空间齿廓进一步优化时,在刚轮与柔轮齿廓之间设定一个齿侧间隙常数,建立谐波传动系统的动力学模型,采用PID控制补偿方法对谐波传动系统的齿侧间隙误差控制补偿进行研究.结果表明,借助仿真数据初步优化后的刚轮空间齿廓与柔轮空间变形能够较好贴合,刚、柔轮的啮合状态得到明显改善;PID控制补偿方法对齿侧间隙造成的系统误差具有较好的调节作用,能在1.5 s内使误差趋近于0,提高了谐波传动系统模型建立的准确性,有利于提高谐波系统的传动精度.

With the rapid development of wearable electronics, novel power solutions are required to adapt to flexible surfaces for widespread applications, thus flexible energy harvesters have been extensively studied for their flexibility and stretchability. However, poor power output and insufficient sensitivity to environmental changes limit its widespread application in engineering practice. A doubly clamped flexible piezoelectric energy harvester (FPEH) with axial excitation is therefore proposed for higher power output in a low-frequency vibration environment. Combining the Euler–Bernoulli beam theory and the D’Alembert principle, the differential dynamic equation of the doubly clamped energy harvester is derived, in which the excitation mode of axial load with pre-deformation is considered. A numerical solution of voltage amplitude and average power is obtained using the Rayleigh–Ritz method. Output power of 22.5 μW at 27.1 Hz, with the optimal load resistance being 1 MΩ, is determined by the frequency sweeping analysis. In order to power electronic devices, the converted alternating electric energy should be rectified into direct current energy. By connecting to the MDA2500 standard rectified electric bridge, a rectified DC output voltage across the 1 MΩ load resistor is characterized to be 2.39 V. For further validation of the mechanical-electrical dynamical model of the doubly clamped flexible piezoelectric energy harvester, its output performances, including both its frequency response and resistance load matching performances, are experimentally characterized. From the experimental results, the maximum output power is 1.38 μW, with a load resistance of 5.7 MΩ at 27 Hz, and the rectified DC output voltage reaches 1.84 V, which shows coincidence with simulation results and is proved to be sufficient for powering LED electronics.

裂缝病害的定期巡检工作是保证市域铁路隧道结构正常运营的关键.针对市域铁路隧道结构表观裂缝的有效识别问题,提出了有监督学习下的市域铁路隧道结构裂缝边缘识别方法.首先,利用消费级数码相机获取了市域铁路隧道结构表观状态的图像数据;然后,基于Canny算子的初步边缘目标检测结果,构造了边缘目标的几何特征矢量,并在此基础上提出了基于几何特征数据的裂缝边缘识别方法;最后,采用实际市域铁路隧道结构的表观图像数据验证了所提出方法的有效性.

：Non-circular gears appeared as early as the 14th century and have a history of more than 700 years.However, the research of non-circular gears is not as long as its history.Due to the special geometry of non-circular gears and the restriction of the design, analysis, manufacture and testing technology in the past, non-circular gears have not been widely used.Nowadays, with the development of computer technology, non-circular gears have again attracted the researchers' attention.In many studies, non-circular gears have applied to more and more application areas.In order to inspire researchers in this field and expand the application field of non-circular gears, the background and development of non-circular gears (mainly cylindrical gears) in the four main research fields: design and analysis, manufacture, testing and application have been summarized and analyzed.Then, the advantages and disadvantages of various theories and methods in the above research fields have been summarized, as well as the problems faced and the possible future development directions.

为能够准确预测超磁致伸缩电静液作动器(M-EHA)的动态输出特性,提出一种考虑流体体积模量和密度变化的非线性动力学建模方法.采用Jiles-Atherton磁滞模型对超磁致伸缩材料的本征非线性进行描述,并通过整流阀振动方程、流量方程、管路压降方程和液压缸动力学方程对流体整体传动特性进行建模.为研究流体体积模量和密度变化的影响,将流体有效体积模量处理为压力的函数,并结合电液模拟理论研究了管路中流体的可压缩性、惯性以及黏性对于M-EHA输出性能的影响,最终建立了其非线性动力学模型.采用4阶龙格库塔法对模型进行迭代求解,并结合试验对比分析,研究了驱动频率、偏置压力以及负载与作动系统输出性能之间的关系.研究结果表明,作动系统输出性能随驱动频率呈双峰变化趋势,且随着偏置压力增加,峰值频率上升,在2.6 MPa偏压时,达到最佳输出水平,为高性能M-EHA的设计开发与优化奠定了理论基础.

： To optimize the assembly line considering rigid tasks constraint, a multi-objective optimization method for automatic assembly line is proposed based on the workstation parallelization and the assembly line sequencing, including: ① Aiming at the features of automatic assembly line considering rigid-constraint tasks, a multi-objective mathematical model is established to simultaneously optimize equipment cost and production efficiency. ② To determine the decision variables, a two-stage encoding/decoding rule is proposed based on the random key method, while precedence relationship, immediate precedence relationship, complete distribution constraint, and parallelism constraints are analyzed. ③ By merging the congestion-based Pareto strategy into the backtracking search optimization algorithm, the considered issue can be optimized. ④ The case study is implemented by taking the automatic circuit breaker assembly line as an example. The result shows that the proposed method is capable to obtain the optimal scheme for the assembly line for both the equipment cost and production efficiency. The optimized scheme (equipment cost is 5.175 million RMB and tact time is 3.2 seconds) is 40.7% and 18.6% improved respectively in terms of production efficiency and equipment cost by comparing with the existing scheme (equipment cost is 6.360 million RMB and tact time is 5.4 seconds).

本文以鲣鱼为仿生对象,根据鱼体形态特征建立单关节和三关节尾鳍机器鱼三维模型和二维仿真模型,基于大幅值细长体理论,建立了两种不同尾鳍摆动形式机器鱼的运动学模型,并根据运动方程编写UDF程序,采用动网格技术定义动边界条件,实现了机器鱼自主游动,并模拟计算了两种尾鳍摆动模式的机器鱼在特定流场下的流场压力及鱼体受力等水动力性能.结果表明,与单关节尾鳍机器鱼相比,三关节尾鳍机器鱼自主游动时流场最大压差减小了13.3％,侧向力幅值减小了52.0％,表明三关节尾鳍机器鱼巡游时更加符合真实鱼游动姿态,具有较大的推进力和较优的平衡性.

针对国内外PE管道内部缺陷检测难题,设计了基于磁悬浮的内部缺陷检测方式.磁悬浮模块使用永磁体和电磁铁结合形成底座,利用磁体之间的排斥力克服悬浮磁块的重力使其悬浮在管道中,实现无接触式内部空间管壁检测.同时通过COMSOL软件对悬浮磁块进行建模与仿真动态分析,找出定子磁环的参数对悬浮力的影响.