基于等效输入的光纤陀螺带宽自主测试方法

针对光纤陀螺频带测试角震动台输入频率低的问题,通过在光纤陀螺反馈阶梯波上叠加正弦信号用于等效外部输入角速度,对陀螺解调输出信号按照幅值进行判断得到陀螺带宽。分析了输入等效正弦波幅值满足条件;针对正弦信号在相位调制器上调制产生的相位差随频率变化的缺点对相位差幅值进行补偿;提出了利用直接数字合成技术生成正弦波信号和极值搜索算法检测信号幅值的带宽检测方案,利用陀螺自身硬件基础实现自主检测。通过建立数字闭环光纤陀螺模型,利用Simulink进行了仿真分析。结果表明该检测算法能实现陀螺频带宽度的全频率范围测量,不受外部输入信号测试频率限制,能够用于光纤陀螺带宽测试。     

新型磨粒在线监测传感器及其试验研究

依据润滑油中磨粒与电感线圈之间耦合关系,设计了1种新型的电感式磨粒传感器,并建立了相应的在线磨粒测试系统.利用在线磨粒监测试验台,对传感器的磨粒检出能力、测试结果的一致性以及测试系统输出与磨粒通过速度的关系进行了试验.结果表明:该在线磨粒监测传感器对粒度大于500μm的铜磨粒和粒度大于100μm的铁磨粒具有较好的检测能力;磁性磨粒收集装置能显著提高传感器对小尺寸铁磁质磨粒的检测能力;在磨粒速度一定情况下,传感器对不同类别不同粒度的磨粒输出一致性好;磨粒速度对测试系统输出影响较大,磨粒速度越快,测试系统输出越小;提高传感器信号放大电路的频响范围,将改善测试系统的响应速度,提高对高速磨粒的检出能力.本研究结论证明该传感器能较好地满足在线磨粒监测的要求.     

大瓣片高强钢球壳板冲压成形应力测试与分析

为对大瓣片高强钢球罐壳板成形过程进行应力测试与分析,在分析壳板成形工艺特点和力学特征的基础上,提出了在板材上附加随动测试架的测试方法,该测试架可随板材运动,实现对传感元件的保护,保证测试信号的输出,同时不干扰壳板的工艺条件,实现了准确测定冲压加工过程中特定状态下板壳内的应力分布及变化规律的目的。测试表明,压力加工过程中,当模具完全冲压到位时,在模具中心区域出现最大拉伸应变,应力值也最大,而卸载后该区反而出现了很小的压应力,这对容器的安全是有利的。因此在压制过程中只要控制冲压变形量,使得中间部位应力值小于材料的强度极限,就可保证板材不发生工艺性破裂,而且成形完成后该区也无不利的力学因素。     

全数字低温漂差动电容检测技术

为降低微小差动电容检测电路的复杂度，提高检测结果的温度稳定性，提出了一种结构简单，无总移相器、滤波器、解调器的全数字检测硬件平台；然后以此硬件平台为基础，设计了检测结果与检测激励信号幅值无关，无总稳幅及温度补偿电路的检测算法。将该技术应用于某差动电容型电子水平仪进行一次启动长期稳定性试验，结果表明在连续24 h内温度变化达12℃时，水平仪的输出变化不超过±1个字（±0.5″），具有优异的温度稳定特性。该技术还可应用于其他任意采用单频正弦信号进行激励的微弱信号检测，如动调陀螺信号检测、微位移传感器信号检测等。     

反射式动栅光纤位移传感器的研究

本文介绍一种新型反射式动栅光纤位移传感器的结构和原理，结合补偿电路消除系统信号漂移，对光电池进行温度补偿。从理论上推导出输出信号与位移的关系，并应用该系统对位移进行了测量。     

飞机壁板紧固件松脱损伤检测的实验研究

基于互相关函数幅值向量的方法,进行飞机壁板紧固件松脱损伤检测的实验研究.以实测得到的抖振载荷信号作为壁板结构的激励信号源,用结构上某点响应信号与其它各点响应信号的互相关函数构造出互相关函数幅值向量;根据不同时期测得的互相关函数幅值向量的变化检测紧固件的松脱损伤.实验结果表明,用此方法可准确检测出传感器附近松脱的紧固件,对于传感器之间的紧固件松脱情况也有较好的检测效果.互相关函数幅值向量直接由结构短时间内的随机振动响应信号得到,而且具有较强的抗测量噪声能力,因此这种检测方法有较好的工程应用可行性.     

结构振动对大型激波风洞气动力测量的干扰

激波风洞起动过程形成冲击载荷激励测力系统的结构振动,气动力测量过程中振动尚未衰减,测力过程可以看作是一个动态的过程,激波风洞中天平输出信号包含了振动干扰的输出信号,现有的解决方法缺乏理论支撑,精度受限. 本文应用振动理论方法,得到了自由振动、强迫振动特性的基本解析结果. 自由振动特性研究中考查了单个振型对测力的干扰及其影响规律以及干扰量幅值随测力截面相对位置的变化规律. 强迫振动特性研究了不同载荷强迫振动下各阶振型对测力的干扰. 研究表明,由于干扰量幅值与加速度幅值的“零点位置” 不重合,传统加速度惯性补偿存在理论上的缺陷. 实验中确定干扰量主要来源需要综合考虑截面位置、载荷作用位置、载荷类型的影响.      

金属材料低温疲劳裂纹起始寿命的微机辅助电位法测试

本文研制了一套适用于低温环境的疲劳裂纹微机辅助电位法测试系统。该系统中采用了翻转电位法、温度补偿和控温信号锁存等技术.对16Mn 钢及 LY12cz 铝合金缺口试件低温疲劳裂纹起始寿命的实际测试结果表明,该系统可比较有效地抑制测试仪器零点飘移、温度波动等造成的干扰,提高了测试精度。实验结果表明,降低温度可使16Mn 钢及 LY12cz 铝合金的疲劳裂纹起始寿命提高。本文还对实验结果及测试系统的进一步改进做了简要讨论。     

西二线管道腐蚀非开挖检测技术研究

针对埋地铁磁管道在非开挖条件下的腐蚀检测难题,对管道弱磁检测技术进行了工程应用验证.该技术利用弱磁检测仪对管道磁信号进行采集,通过分析磁信号曲线图波形特征,可以识别和定位腐蚀缺陷,同时可以根据腐蚀等级指标F值对腐蚀进行评价.首先根据磁信号dBx出现峰值并产生波动、dBy改变方向且过零点、同时dBz也出现峰值并产生波动的...     

低温环境下光纤位移传感器测试系统的实验研究

作者进行了光纤位移传感器在低温环境下的实验研究，分析了传感器的原理，测试了其室温、液氮温度下的静态传输特性，并进行了标定。实验时采取的参考光强度补偿的措施，消除了光源、光纤衰减等波动对测试结果的影响。利用本传感器系统测试了19芯纯Ag包套的高温超导带材Bi222在液氮温度下的应力－应变关系，以及应力－临界电流之间的关系，结果与理论分析相一致。实验结果表明，该传感器可以在液氮温度下正常工作，且具有测量范围大、测试精度高等优点，同时还克服了低温应变片仅能测试出复合材料基体或者包套应变的缺点。     

Auto-calibration of a redundant parallel manipulator based on the projected tracking error

Utilizing the projected tracking error of the redundant joint angles, we studied the calibration problem of the sensor zero positions of a planar 2-dof parallel manipulator in this paper. Based on the study of the relationship between the projected tracking error of the joint angles and the error of the sensor zero positions, a new error function is proposed for the calibration of the sensor zero positions of the parallel manipulator. It is proved that the error function is robust to the measurement error of the joint sensors, so accurate calibration results can be obtained by minimizing the error function even if the measurement of the joint angles is not accurate. With a simple searching strategy for the minimal value of the error function, we designed an auto-calibration procedure and verified the validity of the calibration procedure through real experiments on a real redundant planar 2-dof parallel manipulator.     

导电混凝土传感器的热变形与机敏性研究

摘要 本文设计了具有不同灵敏度的水泥基传感器。测试了传感器的热变形特征与机敏性规律。验证了传感器埋入混凝土进行结构变形检测的可行性。热膨胀系数测定实验发现：与传统认为的受热膨胀不同,添加了碳纳米管的传感器具有热胀-热缩特性。通过对比传感器单独加载与埋入混凝土中加载,发现了大掺量的碳纳米管传感器的压阻效应更易受到混凝土干缩应力的影响。在荷载作用下,传感器的压阻效应会发生变化：压缩应变导致导电填料间距减小致使传感器电阻率减小;微损伤的产生导致导电填料间距增大而致使传感器电阻率增大。两者的竞争机制形成了水泥基传感器压阻效应的非线性特征。本文根据实验结果和电子跃迁的隧道效应理论,建立了水泥基传感器的压阻模型。     

An Embedded 3D Strain Tensor Sensor Based on the Eshelby’s Inclusion

A new design for an embedded strain sensor is proposed in this paper. Based on Eshelby’s inclusion model, it may be used to measure the full 3D strain or stress tensor within any solid body. Currently, common embedded strain sensors are only capable of 1D measurements. The spherical shape of our sensor allows the stress or strain that would exist in the structure without the sensor to be calculated with the aid of the Eshelby theorem (in the case of elastic behavior). We used fiber Bragg gratings to measure the deformation of the sphere - other techniques are also available. Experimental testing was performed in two settings. The first test measured the performance of a polymethylmethacrylate prototype under fluid pressure load. In a second test, a steel prototype sensor was embedded in a standardized concrete specimen under axial compression, and was successfully used to measure 3D strain in real conditions.     

Structural mode filtering of a discrete-parameter system using PVDF sensors

This study presents a modal filtering approach to separate the structural modes of a high-rise structure using shaped film sensors. A building-like model structure is constructed to realize the proposed model filtering approach. Since it is difficult to define a modal shape function for discrete-parameter structures, analytical, numerical, and experimental approaches are discussed to determine the shape of the sensor. In experiment, the first structural mode of a high-rise structure is successfully filtered and the robustness of the sensor output against parameter uncertainty is tested Published in Prikladnaya Mekhanika, Vol. 42, No. 2, pp. 136–142, February 2006.     

Static and dynamic response of a multiplexed-array piezoresistive contact sensor

Multiplexed piezoresistive sensor arrays hold great potential for measuring contact stress distributions for orthopedic research applications. However, their acceptance has been handicapped by output drift and the fact that their dynamic response has not been well characterized. In this report, the static and dynamic responses of one device of this class (the K-Scan piezoresistive contact stress sensor) are formally characterized using a specially made pressure vessel that provides spatially homogeneous contact stress. Drift was predominant early in static loading, reaching relationtive errors of approximately 30 percent over a 10-min period. During loading, first-order dynamic analysis showed that the time constant (and time lag) was nearly zero and there was little attenuation of the output up to 20 Hz. A deconvolution algorithm proved capable of compensating for the great majority of static drift.     

A carbon nanotube sensor for wall shear stress measurement

A novel carbon nanotube (CNT) sensor is being developed to measure the mean and fluctuating wall shear stress (WSS) in a turbulent boundary layer. The CNT WSS sensor is based on the thermal principle and featured by high spatial and temporal resolutions (in the order of nm and kHz, respectively), low power consumption (in the order of μW), and a compact fabrication process compared with traditional WSS measurement sensors. The CNT WSS-sensing element was characterized in detail before its calibration. The CNT sensor was operated under a constant temperature (CT) operation mode and an overheat ratio range of −0.15 to −0.19 and calibrated in a fully developed turbulent channel flow. It has been observed for the first time in a macroscopic flow that the sensor output power is approximately proportional to the 1/3 powered WSS, as expected for a thermal-principle-based WSS sensor, and the wall shear stress measurement is demonstrated for a low Reynolds number flow.     

埋入式封装的光纤光栅传感器应变传递分析

推导了布拉格光纤光栅传感器所测应变与实际结构应变的关系,得出了平均应变传递率并与实际试验结果进行比较. 根据应变传递率确定了光纤的临界粘接长度,并推导了多层粘接时的应变传递情况,讨论了影响应变传递率的因素. 结果表明,光纤光栅的粘贴长度必须大于临界粘贴长度,且光纤光栅传感器所测应变需要加以修正才能得到实际结构应变.     

Direct measurements of local bed shear stress in the presence of pressure gradients

This paper describes the development of a shear plate sensor capable of directly measuring the local mean bed shear stress in small-scale and large-scale laboratory flumes. The sensor is capable of measuring bed shear stress in the range \(\pm\) 200 Pa with an accuracy up to \(\pm\) 1 %. Its size, 43 mm in the flow direction, is designed to be small enough to give spatially local measurements, and its bandwidth, 75 Hz, is high enough to resolve time-varying forcing. Typically, shear plate sensors are restricted to use in zero pressure gradient flows because secondary forces on the edge of the shear plate caused by pressure gradients can introduce large errors. However, by analysis of the pressure distribution at the edges of the shear plate in mild pressure gradients, we introduce a new methodology for correcting for the pressure gradient force. The developed sensor includes pressure tappings to measure the pressure gradient in the flow, and the methodology for correction is applied to obtain accurate measurements of bed shear stress under solitary waves in a small-scale wave flume. The sensor is also validated by measurements in a turbulent flat plate boundary layer in open channel flow.     

A new fabrication process for a flexible skin with temperature sensor array and its applications

This paper reports a novel technique for fabrication of a flexible skin with a temperature sensor array (40×1 sensors). A simplified MEMS technology using platinum resistors as sensing materials, which are sandwiched between two polyimide layers as flexible substrates is developed. The two polyimide layers are deposited on top of a thin aluminum layer, which serves as a sacrificial layer such that the flexible skin can be released by metal etching and peeled off easily. The flexible skin with a temperature sensor array has a high mechanical flexibility and can be handily attached on a highly curved surface to detect tiny temperature distribution inside a small area. The sensor array shows a linear output and has a sensitivity of 7.5mV/℃ (prior to amplifiers) at a drive current of 1 mA. To demonstrate its applications, two examples have been demonstrated, including measurement of temperature distribution around a micro heater of a micro PCR (polymerase chain reaction) chip for DNA amplification and detection of separation point for flow over a circular cylinder. The development of the flexible skin with a temperature sensor array may be crucial for measuring temperature distribution on any curved surface in the fields of aerodynamics, space exploration, auto making and biomedical applications etc.     

海洋重力测量误差补偿技术

海洋重力场信息在勘探矿源和导航定位等方面都具有重要意义.进行海洋重力实时测量时,重力仪会受到各种外界扰动力的影响,再加上重力敏感器本身稳定性和惯性平台系统性能影响,重力敏感器的输出需要进行一系列数据处理和补偿后才能得到当地重力异常值,研究了重力敏感器安装角误差标定、零位漂移估计和格值修正等重力数据预处理方法.分析了海洋重力测量数据处理流程,主要包括零点漂移补偿、水平加速度误差补偿、厄特弗斯效应修正、高度修正和噪声滤波处理等.对每个数据处理过程都提出了具体补偿算法,并分析了补偿后的重力测量误差,将以上重力数据处理方法应用到实际重力测量,结果表明重力仪能够准确测量出当地重力值,其精度为1 mGa1.