强度调制的光纤布拉格光栅磁场传感器

设计了一种基于光纤布拉格光栅啁啾效应的磁场传感器,导出了光纤布拉格光栅的反射谱带宽与磁感应强度的关系。传感器工作时,磁场中的圆盘形软铁受到通电螺旋管线圈磁场力的作用,引起矩形悬臂梁变形,从而导致粘贴在悬臂梁侧边的光纤布拉格光栅的反射光谱带宽发生变化;利用光谱分析仪,通过检测光纤布拉格光栅反射谱带宽的变化量,即可得到被测磁场磁感应强度的大小。当光谱分析仪的分辨率为0.001nm时,可测量磁感应强度为6~70mT。实验结果表明:该光纤布拉格光栅反射光谱带宽的变化量对温度变化不敏感,当温度从0℃变化到45℃时,3dB带宽的变化小于8pm。实验结果和理论分析一致,表明该方案切实可行。     

高斯光束焦深探析

对聚焦激光光束焦深的不同定义作了比较分析，并对基模高斯光束的光强分布作了数值计算，作出了等光强分布曲线。同时对高阶模情况也作了一定分析。对不同情况下激光光束焦深的合理选用进行了讨论。     

应用于光强扫描的三维控制系统

介绍了应用于光强扫描的三维控制系统.该系统用VB编写控制界面,通过数据采集卡实现计算机对三维平移台的控制和对空间光强分布的实时采集,根据空间扫描所记录的空间光强分布情况,计算出折射角的大小;并针对热敏探测器响应时延的问题,介绍了消除响应时延造成的误差的方法.     

非驱动轮毂轴承单元法兰盘轴颈静强度计算及试验

针对轮毂单元静强度计算及试验验证问题,根据第三代非驱动轮毂轴承单元的受力情况,提供了一种用CAE仿真分析方法以外的简便数值分析计算方法,即在车辆受到侧向1.2 g的临界侧向加速度下,将轮毂轴承单元受到的外部径向力和轴向力,通过轮毂轴承单元内部受力分析,转化为轴承内部双列滚道的两个载荷中心的径向力和轴向力;并将轮毂轴承单元法兰盘内侧受力轴颈简化等效为实心悬臂梁的处理方法,来计算法兰盘轴颈静强度;并用侧向静强度试验方法,通过构建适当的试验方案,来验证轮毂轴承单元法兰盘静强度,为设计优化提供简便的分析验证方法。研究结果表明,该简化模型计算结果能够与侧向静强度试验结果保持一致,为笔者利用简化计算方法来简便快速地定量选取轴径和轴颈r角大小提供了可能;该方法计算简便有效,结果可靠。     

脚踏式下肢康复机器人足底力检测方法及装置

足底压力是患者进行康复训练时非常重要的生物力学参数。针对脚踏式下肢康复机器人,提出了一种新的基于弹性梁应变检测足底压力的方法,并设计了检测装置。通过分析人体足底力分布,选取足部四个主要受力点作为测量点;利用有限元仿真分析确定力与弹性梁应变的关系,建立了计算足底压力的数学模型;仿真与计算结果的对比,表明该方法及装置可实现对足底信息中重要的足底力大小的精确检测。利用该方法及装置可得到患者在训练过程中足底压力分布情况,可以用来康复评定,检测痉挛等,具有重要的临床意义。     

基于可靠度仿真的MEMS加速度开关结构优化

基于MEMS加速度开关的结构与作用原理,利用ANSYS对悬臂梁进行有限元分析,获得在冲击载荷作用下悬臂梁的受力情况以及位移的大小; 采用蒙特卡罗方法产生伪随机数,模拟不同样本变量的随机分布情况,以解决试验样本不足的问题,对MEMS加速度开关的可靠度进行了分析计算; 采取改进结构以优化设计,降低开关的潜在危险和失效概率,提升可靠度。     

周期和随机分量叠加而成粗糙表面的激光散射

研究了机械加工时由周期分量和随机分量叠加形成的粗糙表面的激光散射特性.基于Helmholtz-Kirchhoff积分定理并结合统计学相关理论,推导得到了上述粗糙表面的散射场强空间分布理论计算公式.根据推导得到的计算公式,计算了不同周期振幅和不同随机粗糙度情况下的散射场强空间分布,并分析了散射场空间分布的特征和形成原因.理论计算结果表明:在随机性粗糙度远小于激光波长时,周期振幅越大,散射场空间分布的“衍射条纹”现象越明显;而在随机性粗糙度和激光波长可比拟时,周期振幅在波长范围内的变化对散射场空间分布特征影响较小,不再有“衍射条纹”出现.在这种情况下,周期振幅的变化所产生的效果相当于是对散射场空间分布进行了调制.     

新型盾构机刀盘空间RCCR机构支撑结构受力分析

基于新型盾构机刀盘工况,对三对传力杆空间RCCR机构进行了受力分析。结果表明:对支撑结构进行纯刚体研究或柔性化处理,其受力情况不同;对支撑结构进行柔性化处理后,得到该处Z向约束力的大小与示力副处Z向约束力的大小相差一个数量级。     

基于光强调制和数字拟合的PSD位置检测方法的研究

为了实现对微小位置信号的精密测量,建立了PSD位置检测系统。对该系统的光强调制方法、测量原理、位置测量算法及误差评估进行了研究。实验发现当信号光强微弱时,位置敏感器件(PSD)受背景光强影响很大。采用正弦调制光强,通过带通放大的方式,克服背景光强的影响,极大地提高了测量系统的信噪比。针对所提取的PSD光强差与和信号均为调制频率信号,且幅值与相差由光斑位置决定的特点,提出应用同步A/D与椭圆拟合法计算光斑位置的方法,并对相关计算公式进行了理论推导。实验结果表明:在测量范围达到9 mm的条件下,测量精度可达到0.01 mm.基本满足PSD位置检测方法的稳定可靠、测量精度高、抗干扰能力强等要求。     

TBM盘型滚刀不同磨损状态下的切削力预测

基于ABAQUS/Explicit非线性显式动力学有限元计算,分析了滚刀在不同磨损厚度和不同磨损刃角的受力,以及滚刀与岩石的接触压力。计算结果显示,在不同磨损条件下,滚刀所受的贯入力是滚动力的3倍,侧向力可以忽略不计。在均匀磨损条件下,滚刀受力和接触压力随磨损加剧也快速增大。在刃角磨损条件下,滚刀受力和接触压力不随刃角变化成比例增加,具有一定随机分布特性,其最大值和无磨损滚刀受力最大值差异较小。这些结论为TBM的结构设计、滚刀的寿命预测和动力学分析提供了参考依据。     

AFM悬臂定位系统中光干涉误差及减小方法研究

光杠杆法是原子力显微镜（AFM）悬臂定位的主要方法。由于悬臂自身的尺寸和材料特性、检测光路系统等因素制约，悬臂弯曲测量时存在光泄露。被试样表面反射的部分泄露光与悬臂反射光产生干涉，在探针一试样接近曲线中产生光干涉误差。基于轻触模式AFM，分析了光干涉误差的产生原因，并对其引起的AFM测量误差进行了数学分析和仿真、提出了减小光干涉误差的方法。实验结果和理论分析表明，为了进一步提高AFM的测量精度，有必要克服定位系统中的光干涉误差。     

Note: A novel integrated microforce measurement system for plane-plane contact research

The evaluation of plane-plane contact force has become a big issue in micro-/nano research, for example in microassembly. However with the lack of effective experimental equipments, the research on plane-plane contact has been limited to theoretical formulations or virtual simulation. In this paper, a microforce sensor and precision parallel robot integrated system is proposed for the microforce measurement of plane-plane contact. In the proposed system, the two objects are fixed on the parallel robot end-platform and the microforce sensor probe tip, respectively, and the high precision robot system is employed to provide six degree-of-freedom motions between both objects. So it is convenient for the microforce measurement between the planar objects with different orientations. As a significant application, the proposed system is utilized for measurements of pull-off force between planar objects, in which the validation of the system is demonstrated in practice. The proposed microforce measurement system is generic, which can be extended to a variety of microforce measurements in plane-plane contact.     

Influence of Poisson's ratio variation on lateral spring constant of atomic force microscopy cantilevers

Atomic force microscopy (AFM) can be used to measure the surface morphologies and the mechanical properties of nanostructures. The force acting on the AFM cantilever can be obtained by multiplying the spring constant of AFM cantilever and the corresponding deformation. To improve the accuracy of force experiments, the spring constant of AFM cantilever must be calibrated carefully. Many methods, such as theoretical equations, the finite element method, and the use of reference cantilever, were reported to obtain the spring constant of AFM cantilevers. For the cantilever made of single crystal, the Poisson's ratio varies with different cantilever-crystal angles. In this paper, the influences of Poisson's ratio variation on the lateral spring constant and axial spring constant of rectangular and V-shaped AFM cantilevers, with different tilt angles and normal forces, were investigated by the finite element analysis. When the cantilever's tilt angle is 20 degrees and the Poisson's ratio varies from 0.02 to 0.4, the finite element results show that the lateral spring constants decrease 11.75% for the rectangular cantilever with 1muN landing force and decrease 18.60% for the V-shaped cantilever with 50nN landing force, respectively. The influence of Poisson's ratio variation on axial spring constant is less than 3% for both rectangular and V-shaped cantilevers. As the tilt angle increases, the axial spring constants for rectangular and V-shaped cantilevers decrease substantially. The results obtained can be used to improve the accuracy of the lateral force measurement when using atomic force microscopy.     

均匀光强分布的5kW半导体激光硬化光源研制

随着半导体激光自身输出功率和转换效率的提升,半导体激光已经广泛的应用于激光加工领域。本文针对目前激光加工领域对半导体激光硬化光源的需求,研制了波长为976nm的连续输出半导体激光硬化光源。该光源采用空间/偏振合束工艺达到了较高的合束效率,采用柱面微透镜阵列分割与聚焦镜复合较好地匀化了巴条激光器慢轴方向固有的光强起伏,使聚焦光斑的光强呈平顶分布。最后对该光源进行了实验装调和测试。结果表明,在工作电流为93A时,光源的最大输出功率为5 120W,电光转换效率达47%,光斑尺寸为2mm×16mm,光斑分布为平顶分布,平整度大于90%,满足工业中对大面积、高效率激光硬化的要求。     

Self-sensing piezoresistive cantilever and its magnetic force microscopy applications

A newly developed Si self-sensing piezoresistive cantilever is presented. Si piezoresistive cantilevers for scanning microscopy are fabricated by Si micro-machining technique. The sensitivity of the piezoresistive cantilever is comparable to the current laser detecting system. Topographic images are successfully obtained with the piezoresistive cantilever and some comparisons are made with the laser detecting system. Furthermore, the magnetic film (Co-Cr-Pt) is coated on the tip of the piezoresistive cantilever for magnetic force microscopy (MFM) application. The magnetic images are successfully obtained with the self-sensing MFM piezoresistive cantilever. The self-sensing piezoresistive cantilevers have been successfully applied in scanning probe microscopy and MFM.     

具有三维力反馈的原子力显微镜纳米操作系统

在基于原子力显微镜的纳米操作过程中，由于缺乏实时反馈信息，造成纳米操作效率低下且灵活性差，同时探针因受力过大而损坏。为此，本文通过对探针受力-悬臂变形进行建模，并根据实时检测到的悬臂变形信号、新的参数获取与校准方法，从而获取探针所受的实时三维纳米力。将此三力经比例放大后送人力／触觉设备进行感知，操作者就可以实时调节施加在探针上力的大小及探针的运动轨迹，使得操作的效率及灵活性明显提高，且可以避免探针因受力过大而造成损坏。纳米刻画和多壁碳纳米管的操作实验验证了系统的有效性。     

基于M-Z干涉光路的光学目标探测

为了进一步提高激光主动探测系统对光学目标的探测识别能力,提出了一种利用扫描干涉场将目标的空间分布特征加载到反射光时间序列信号中,通过反射光时间分布的特征差异在复杂漫反射背景中探测光学目标的新方法。基于马赫-曾德尔干涉光发生体制,得到了远场干涉图样条纹间距与传输距离、M-Z干涉光发生装置参数和激光波长的关系式。分析了条纹间距对不同目标原路返回点处光强时间分布特性的影响。搭建了演示验证平台,结果显示,随着干涉场的条纹间距减小,光学目标的反射光时间分布峰峰数增多,峰峰比降低,而漫反射目标没有明显变化。漫反射目标和光学目标的反射光时间分布的方差、偏度和峰度等统计特征差异明显,其中峰度值分别为(4.37,62.8)、(4.03,34.97)和(3.91,35.4),整体相差一个数量级。利用反射光时间分布的包络形态和统计特征的较大差异可快速区分光学目标与漫反射背景。     

Mechanical and dynamic characteristics of double and single beam cantilevers for MEMS manipulation

Micro and millimeter-scaled cantilever beams are commonly used to apply and measure microforce and manipulate micro-objects, biological cells, and tissues. In manipulating micro-objects and actuating micro-devices by cantilever beams, sudden application and release of forces are typical, and subject to static and dynamic modes of operation. Therefore, the cantilever’s mechanical behavior and vibration characteristics are vital since they are also used in force sensors and probes. The dynamic behavior of the double beam cantilever (DBC) in micro and millimeter-scaled is explored by varying the length without changing the stiffness and compared with the single beam cantilever (SBC). The dynamic attributes such as mode shape, natural frequency, resonance, and response under the impulse force and Coulomb friction are evaluated numerically. This study will assist in selecting the appropriate type and length of cantilevers in micro and millimeter-scale to manipulate micro-objects, biological cells and tissues, and use in MEMS sensors.

     

基于两种扫描方式的PSD响应特性

光源不同扫描方式直接影响PSD对位置探测的准确性。给出直接扫描和光照稳态后扫描两种方式照射下一维PSD的解析解，以及光入射位置的计算值与实际值的误差曲线。结果表明，两种扫描方式造成光生电流的输出范围不同，光照稳态后扫描方式比直接扫描方式能更真实的反映光入射位置信息，能够获得较高的探测精度。     

Optical interference artifacts in contact atomic force microscopy images

Atomic force microscopy images are usually affected by different kinds of artifacts due to either the microscope design and operation mode or external environmental factors. Optical interferences between the laser light reflected off the top of the cantilever and the light scattered by the surface in the same direction is one of the most frequent sources of height artifact in contact (and occasionally non-contact) images. They are present when imaging highly reflective surfaces, or even when imaging non-reflective materials deposited onto reflective ones. In this study interference patterns have been obtained with a highly polished stainless steel planchet. The influence of these artifacts in surface roughness measurements is discussed, and a semi-quantitative method based on the fast Fourier transform technique is proposed to remove the artifacts from the images. This method improves the results obtained by applying the usual flattening routines.