用BP神经网络诊断电动机断条

本文对感应电动机故障诊断原理和方法进行了分析，并以电流频谱分析法为基础，应用BP神经网络诊断感应电动机转子断条数，给出了网络训练和测试结果，该方法根据感应电动机的运行状态参数，可以直接诊断出感应电动机转子的断条数的多少，具有智能化诊断，诊断准确，精度高等特点。该方法已应用于作者开发的虚拟电机故障分析诊断仪中，取出了很好的效果。     

利用红外热像技术快速确定材料疲劳极限

基于能量理论，阐述了利用红外热像方法确定材料疲劳极限的原理，并利用红外热 像仪对具有矩形截面的钢试件进行了疲劳试验，通过记录疲劳试验过程中试件表面的温度变 化，经处理后得到了该种材料的疲劳极限. 试验表明，利用红外热像技术可以快速、准确地 确定材料的疲劳极限. 同时，该方法还具有可靠、经济、便捷等优点.     

TDLJ天平式电机转矩测试仪

本文论述了测量微特电机转矩的 TDLJ 测试仪的组成、结构特点、测试工作原理和技术性能,同时列举了由其直接测量的永磁直流力矩电机的堵转转矩、转矩波动特性曲线、磁干扰转矩分布特性曲线、总干扰转矩分布特性曲线和陀螺电机的转矩 M=f(t)动态特性曲线,并且列表汇总了上述电机相应的各种状态下转矩数值。     

硅微型两自由度振动轮式陀螺仪的研究

本文详细介绍了一种利用微电子加工工艺制作的硅微型两自由度振动轮式陀螺仪的新结构 ,分析了该种陀螺仪的工作原理 ,推导了陀螺仪动力学方程 ,并讨论了梳状谐振器的工作机理和陀螺仪模拟力反馈的闭环控制方案 ;目前已制作完成了该型陀螺仪的原理样机     

薄型超声电机与定子振动模态的激发

论述了薄型超声电机的工作机理。分析了电机压电片的布置与激励信号的关系，探讨了定子弯曲模态的激发问题。设计并制作了一种新的薄型超声电机。电机转子安装在圆环定子内，能够显著减小电机厚度，电机定子采用双压电片结构，可以避免激发出定子的非轴称模态。完成了电机运转实验，电机运转平稳。     

星载静电加速度计加转回路建模与分析

新型等效原理实验通过检验两个相同材料但自旋运动有显著差异的宏观物体的自由落体运动来验证等效原理可能存在的破坏。根据新型等效原理空间实验的科学目标,提出了一种星载差分静电加速度计方案,设计了基于可变电容式电机原理的静电加转回路;在分析了作用于转子上的静电加转力矩、残余气体阻尼及磁场阻尼的基础上,建立了转子加转回路的动力学模型并进行了仿真分析;仿真结果表明,启动过程使转子达到目标转速(10 000 rpm)的启动时间为9.8天。静电加转方法可在电极筒上同时配置加转电极与悬浮电极,结构紧凑,同时避免了传统的异步电机加转产生的电磁干扰。     

立式电机模态仿真与实验研究

振动是电机的重要性能指标。本文在MSC.NASTRAN仿真环境下,利用有限元方法对立式电机进行了电机整机的模态仿真,得到了整机的前五阶固有振动频率、振型等参数值。根据仿真结果,分析了整机的危险位置和振型。进行了电机模态试验,验证虚拟样机和数值模拟的有效性。结果表明,系统不会发生共振。最后,在力学分析的基础上对结构进行优化,为立式电机的改进和振动测试提供了参考。     

纵扭复合型超声电机预压力和输出扭矩的关系

建立了纵扭复合型超声电机定子和转子之间的接触模型,根据模型讨论了预压力、纵振激振电压、扭振激振电压、摩擦力及电机能提供的最大扭矩之间的关系。指出在一定的条件下,施加某一预压力时电机的输出扭矩最大。所得计算结果和实验结果基本吻合。     

基于MATAB/Simulink的双电机速度跟踪伺服系统仿真

在分析直流无刷电机的数学模型的基础上,通过研究双电机速度跟踪伺服系统的结构与运行原理,对系统建立有效的仿真模型,完成了系统的计算机仿真.在MATLAB/Simulink环境下,采用基于位置的电控式跟踪控制策略,构建了双电机速度跟踪伺服系统仿真模型,主电机采用速度、电流双闭环控制,从电机在双闭环基础上外加位置环完成速度跟踪,并选择数字PID控制算法对系统进行仿真实验.仿真试验结果与系统设计要求一致,验证了数学模型的有效性及控制系统的合理性,有利于加快实际系统设计和调试的进程.     

无静摩擦力矩的无刷直流力矩电机

提出了一种电枢上无铁芯的无刷直流力矩电机，该电机无静摩擦力矩。推导出了这种电机的电流、力矩和反电势等参数的计算公式，给出了这种电机的合理设计方法，然后按提出的设计公式和设计思路设计了一种新型力矩电机—无静摩擦力矩的无刷直流力矩电机。对该电机的实际测试表明，该力矩电机不仅无静摩擦力矩，而且还有电气时间常数小、力矩系数大、功耗低、制造工艺简单等优点，同时也证明了文中给出的计算方法是正确的。     

多孔格栅均匀化模型平压仿真分析

为了研究均匀化方法在一种多孔格栅结构中的应用,从格栅单胞尺度入手,建立了一种适用于有限元仿真分析的三维周期性边界条件.以ABAQUS作为分析平台,对周期性边界条件下的格栅单胞模型进行了平压仿真分析,并将仿真结果与文献实验结果对比,验证了该边界条件的可靠性.利用均匀化理论建立了格栅单胞力学平衡方程,得到了格栅均匀化模型....     

刚柔耦合定位平台结构-运动-控制一体化建模

针对微电子制造行业等领域中的长行程高精度定位问题,提出了一种刚柔耦合定位平台,并建立了其结构-运动-控制一体化动力学仿真模型。首先,根据刚柔耦合定位平台的结构特点对浮动坐标法进行修改,建立了简洁高效的动力学仿真模型。其次,结合动力学模型、3阶S型曲线和经典的PID控制方法建立了结构-运动-控制一体化仿真模型。最后,通过数值算例对仿真模型的有效性进行了验证。数值模拟结果显示,建立的结构-运动-控制一体化仿真模型能够有效地对定位平台的工作过程进行模拟,为后续的结构优化、运动规划和控制系统设计等工作创造条件。     

CAD软件在工程地质三维建模中的应用

如何快速、准确地建立地质体的三维模型一直是众多岩土工程数值模拟工作者所面临的难题。虽然三维地学模拟软件具有很好的三维地质建模能力,但是由于数据结构的差异,采用他们现行三维地学模拟软件建立的地质模型难以导入数值模拟分析软件中,以为相应工程问题的数值模拟服务。目前,随着各种CAD、CAM软件行业的的飞速发展,涌现出了许多优秀的三维建模软件,而且这些软件大都与现行数值分析软件有着良好的数据接口功能。据此,本文提出了采用现行CAD软件来建立工程地质体的三维模型,使得建立的模型达到既"可视"又"可算"的目的。将其应用于云南某高速公路边坡的三维建模中,证明了该法具有方便、快捷和合理等优点。     

Longitudinal dynamics of a tracked vehicle: Simulation and experiment

In recent years virtual dynamic system simulation has become very important in the design and development stage, as new strategies can be examined without expensive measurements and with reduced time. This paper describes the development of a simulation model for transient analysis of the longitudinal dynamics of a heavy tracked vehicle. The driving inputs for this simulation model are obtained from a powertrain model. The main elements of the powertrain include the engine, Torque Converter (TC), transmission and drivetrain. Here the engine is modeled based on the engine maps from steady-state experiments. The TC is modeled based on its characteristic map from experiments. A fairly simple transmission model is used which is based on static gear ratios assuming small shift times. The final drivetrain model however includes the rotational dynamics of the sprocket. The simulation model developed is validated by comparing the predicted values with the measured data from experiments. The results have demonstrated that the developed model is able to predict fairly accurately the acceleration and braking performance of the heavy tracked vehicle on both soft and hard terrain.     

Simulations of free surface flows with implementation of surface tension and interface sharpening in the two-fluid model

Two-fluid model used for free surface flows with large characteristic scales is improved; the smeared interface is sharpened with conservative level set method and the surface tension force with wetting angle is implemented. Surface tension force is split between two phases with several models. Detailed analysis showed the splitting of surface tension force with volume averaging as the most appropriate. The improved two-fluid model with interface sharpening and implemented surface tension is validated on several test cases. The pressure jump over a droplet interface test case showed that the pressure jump in simulation converges with grid refinement to the analytical one. The parasitic currents in simulation are one order of magnitude larger than in simulation with volume of fluid model. In the oscillating droplet test case the time period of oscillating droplet with initially ellipsoid or square shape is similar to the analytical time period. In the rising bubble test case, the rising bubble position, terminal velocity, and circularity are similar to the one observed in simulations with level set model. The wetting angle is implemented in the two-fluid model with interface sharpening and surface tension force. Model is tested in the simulation of droplet in contact with wall with different wetting angles.     

基于GIS与数值模拟的三峡水库库首区诱发地震危险性评价

采用GIS与数值模拟相结合的方法对三峡水库库首区诱发地震危险性进行评价。通过研究水库诱发地震的影响因素,建立模型进行数值模拟。在GIS平台上,综合数值模拟结果与诱发地震监测结果,建立危险性评价数据库。在GIS支持下,采用最大拉应变准则判别拉伸破坏,采用摩尔-库仑准则判别剪切破坏,对单元进行评价。利用诱发地震监测资料,以发生诱发地震单元的第一主应力、第三主应力、位移作为危险单元的标准,对单元进行二次评价。研究结果表明,建立同一GIS平台下的水库区地质环境、监测资料数据库是建立多因素综合评价模型的基础。采用地震评估模型对模拟结果进行评估,结合监测资料对评估成果进行修正,在三峡库首区水库诱发地震危险性评价中具有一定的可信度。     

System-level simulation of vibratory micromachined gyroscope with fence structure

An equivalent circuit model of a novel fence structure vibratory micromachined gyroscope‘s oscillating properties is modeled by electrical equivalent circuits according to its dynamics equation. Equivalent circuit model of oscillating and differential detection capacitance model are implemented in the circuit simulation tool PSPICE, which is available in oscillating properties analysis such as oscillating‘s transient response, steady response and frequency response to angular rate to optimize working mode of the gyroscope. The model also enables sensor simulation with the interfacing electronics to analyse the performances of the whole system. Behavioral simulation of the system is performed to prove the function of detection circuits. The simulation results and measurement results show that the design of circuits is feasible.     

Simulation of a soil loosening process by means of the modified distinct element method

We apply the Distinct Element Method (DEM) to analyze the dynamic behavior of soil. However, the conventional DEM model for calculation of contact forces between elements has some problems; for example, the movement of elements is too discrete to simulate real soil particle movement. Therefore, we modify the model to solve the difficulties. To investigate the validity of the modified model, we conduct an experiment in which soil is cut with a pendulum-typeblade, and simulate the soil loosening process with the modified DEM model. This paper presents details of the experimental apparatus and the comparison of soil behavior and energy absorption between the simulation and the experiment. Some characteristic phenomena of the experiment are reproduced in the simulation giving us confidence that the modified model is better than the conventional model for the simulation of soil behavior.     

碎片云SPH方法数值模拟中的材料失效模型

光滑粒子流体动力学方法（smoothed particle hydrodynamics,SPH）被广泛应用于薄板超高速撞击碎片云的数值模拟。利用AUTODYN软件中的SPH模块,考察了无失效模型、Grady失效模型和最大拉应力失效模型3种方案下碎片云模拟结果,发现无失效模型时计算结果及材料表现与实验明显不符;相比于Grady失效模型,最大拉应力失效模型下材料更难失效,将小幅度减弱碎片云扩散程度,碎片总数减少,粒子聚集产生更大碎片,碎片云侵彻性能提高,增大模型失效阈值亦有上述表现。相比而言,Grady失效模型计算结果更符合实验,但2种失效模型间差异与撞击工况相关,材料破碎越充分差异越小。     

Numerical simulation and testing verification of the interaction between track and sandy ground based on discrete element method

Tractive effort of tracked vehicles plays an important role in military and agricultural fields. In order to solve the problem of low precision in numerical simulation of the interaction between track and sandy ground, a systematic and accurate discrete element modeling method for sandy road was proposed. The sandy ground was modeled according to the mechanical parameters measured by soil mechanics tests. The interaction coefficients of sandy soil were measured by the repose angle test and triaxial compression test combined with the corresponding simulation. On this basis, a discrete element interaction model of track-sandy ground was established, which can be used to test the tractive effort of track. Numerical simulation calculation of track model at different speeds was carried out, and the simulation results were compared with the results of indoor soil bin test for verification. The verification results show that the interaction between track and sandy ground based on DEM simulation is consistent with the actual soil bin test. The discrete element modeling method in this paper can be used to model the track and sandy ground accurately, and the simulation model can be used to test the tractive effort of tracked vehicle.