Micro thermal shear stress sensor based on vacuum anodic bonding and bulk-micromachining

This paper describes a micro thermal shear stress sensor with a cavity underneath, based on vacuum anodic bonding and bulk micromachined technology. A Ti/Pt alloy strip, 2μm×100μm, is deposited on the top of a thin silicon nitride diaphragm and functioned as the thermal sensor element. By using vacuum anodic bonding and bulk-si anisotropic wet etching process instead of the sacrificial-layer technique, a cavity, functioned as the adiabatic vacuum chamber, 200μm×200μm×400μm, is placed between the silicon nitride diaphragm and glass （Corning 7740）. This method totally avoid adhesion problem which is a major issue of the sacrificial-layer technique.

表贴式矿用FBG传感器应力传感特性分析研究

本文重点对表贴式矿用光纤布拉格光栅(FBG)传感器应力传感特性进行了分析研究,针对表贴式FBG传感器应力传感特性受基体剪切模量进行系统性的分析,建立表贴式FBG应变三层结构理论分析模型,推导表贴式FBG的应变传递数学表达式,从基体的剪切模量角度分析矿用FBG传感器应力传感特性。通过试验分析总结,得出铜基体材料应变和波长线性关系最佳,可达99.89%,表贴式FBG基体剪切模量越大,应力与波长线性度越好,为矿用FBG传感器结构设计和灵敏度优化提供理论研究基础。

电子剪切散斑3CCD传感图像特征去噪优化检测方法

针对CCD(Charge-Coupled Device)光学传感器采集电子剪切散斑干涉图像特征由于散斑指数高、峰值信噪比低,导致剪切散斑图质量差、检测效果不佳的问题,提出一种电子剪切散斑3CCD传感图像特征去噪优化检测方法。该方法分析了电子剪切散斑技术在三维物体表面变形检测中产生问题的原因,采用3CCD图像传感器替代单CCD图像传感器,引入同态滤波降噪处理图像,设计一种相位干涉技术,结合Canny检测算法,实现电子剪切散斑去噪优化检测。实验结果表明,应用3CCD传感器结合去噪技术的电子剪切散斑智能检测方法,图像散斑指数更低、峰值信噪比更高、检测时间更短,分别为0.0234、19.5 dB、16.2 ms,并且三维物体表面变形测量误差在0.09 mm内,该方法有效提高了图像质量,从而提高了实际应用价值。

剪板机间隙补偿设计

针对剪板机由于其结构参数不合理导致上下刀片间隙或大或小所导致剪切产品质量差的问题,在对剪板机在正常工作状态下应力和位移测试的基础上寻找其根本原因;而后,基于数值模拟计算手段对上刀片机架和下刀片工作平台的结构参数进行优化,并对优化效果进行综合评估。

剪切梁结构扭矩传感器的应变解析

为实现对机器人在复杂情况下的灵活控制,需要在机器人关节处增加扭矩传感器,扭矩传感器是获取机器人关节运行状态的重要检测部件。考虑机器人自身尺寸限制及工作场景等因素,扭矩传感器采用轮辐式结构。本文介绍了扭矩传感器的结构和工作原理,分析了传感器弹性横梁在扭矩载荷作用下的变形协调条件,基于变形协调条件和铁木辛柯梁理论推导了剪切梁的应变计算公式,并建立了简化力学解析模型。通过有限元分析对力学模型的准确性和对弹性体结构参数的敏感性进行了验证。算例结果表明,该简化力学模型得出的结果和有限元结果数值相对误差在8.9%以内,表明了该简化力学解析模型的准确性。

采用双剪力传感器的铁路货车超偏载检测装置设计

针对在既有线安装铁路货车超偏载检测装置存在的施工周期长、成本高、对线路条件要求高等问题,设计一种采用双剪力传感器的铁路货车超偏载检测装置。在介绍采用双剪力传感器的铁路货车超偏载检测装置设计原理的基础上,分析这种铁路货车超偏载检测装置的总体技术要求及设计方案,评定其测量不确定度,并进行检定和应用验证。结果表明,采用双剪力传感器的铁路货车超偏载检测装置各秤量点的重量测量结果不确定度均小于称重最大允许误差的1/3,满足计量性能要求;重量、偏重和偏载率检定结果均满足设计要求;与现有铁路货车超偏载检测装置测得的货车重量、偏重差、偏载率相比,采用双剪力传感器的超偏载检测装置测得的货车重量、偏重差、偏载率的偏差均较小,检测结果准确度满足货运安全检测要求。

Experimental Study on the Bed Shear Stress Under Breaking Waves

The object of present study is to investigate the bed shear stress on a slope under regular breaking waves by a novel instrument named Micro-Electro-Mechanical System （MEMS） flexible hot-film shear stress sensor. The sensors were calibrated before application, and then a wave flume experiment was conducted to study the bed shear stress for the case of regular waves spilling and plunging on a 1 ： 15 smooth PVC slope. The experiment shows that the sensor is feasible for the measurement of the bed shear stress under breaking waves. For regular incident waves, the bed shear stress is mainly periodic in both outside and inside the breaking point. The fluctuations of the bed shear stress increase significantly after waves breaking due to the turbulence and vortexes generated by breaking waves. For plunging breaker, the extreme value of the mean maximum bed shear stress appears after the plunging point, and the more violent the wave breaks, the more dramatic increase of the maximum bed shear stress will occur. For spilling breaker, the increase of the maximum bed shear stress along the slope is gradual compared with the plunging breaker. At last, an empirical equation about the relationship between the maximum bed shear stress and the surf similarity parameter is given, which can be used to estimate the maximum bed shear stress under breaking waves in practice.

Experimental Research on Boundary Shear Stress in Typical Meandering Channel

A novel instrument named Micro-Electro-Mechanical System(MEMS) flexible hot-film shear stress sensor was used to study the boundary shear stress distribution in the generalized natural meandering open channel, and the mean sidewall shear stress distribution along the meandering channel, and the lateral boundary shear stress distribution in the typical cross-section of the meandering channel was analysed. Based on the measurement of the boundary shear stress, a semi-empirical semi-theoretical computing approach of the boundary shear stress was derived including the effects of the secondary flow, sidewall roughness factor, eddy viscosity and the additional Reynolds stress, and more importantly, for the first time, it combined the effects of the cross-section central angle and the Reynolds number into the expressions. Afterwards, a comparison between the previous research and this study was developed. Following the result, we found that the semi-empirical semi-theoretical boundary shear stress distribution algorithm can predict the boundary shear stress distribution precisely. Finally, a single factor analysis was conducted on the relationship between the average sidewall shear stress on the convex and concave bank and the flow rate, water depth, slope ratio,or the cross-section central angle of the open channel bend. The functional relationship with each of the above factors was established, and then the distance from the location of the extreme sidewall shear stress to the bottom of the open channel was deduced based on the statistical theory.

Analytical Higher-Order Model for Flexible and Stretchable Sensors

The stretchable sensor wrapped around a foldable airfoil or embedded inside of it has great potential for use in the monitoring of the structural status of the foldable airfoil.The design methodology is important to the development of the stretchable sensor for status monitoring on the foldable airfoil.According to the requirement of mechanical flexibility of the sensor,the combined use of a layered flexible structural formation and a strain isolation layer is implemented.An analytical higher-order model is proposed to predict the stresses of the strain-isolation layer based on the shear-lag model for the safe design of the flexible and stretchable sensors.The normal stress and shear stress equations in the constructed structure of the sensors are obtained by the proposed model.The stress distribution in the structure is investigated when bending load is applied to the structures.The numerical results show that the proposed model can predict the variation of normal stress and shear stress along the thickness of the strain-isolation（polydimethylsiloxane）layer accurately.The results by the proposed model are in good agreement with the finite element method,in which the normal stress is variable while the shear stress is invariable along the thickness direction of strain-isolation layer.The high-order model is proposed to predict the stresses of the layered structure of the flexible and stretchable sensor for monitoring the status of the foldable airfoil.

Modeling of sensor function for piezoelectric bender elements

An analytical sandwich beam model for piezoelectric bender elements is derived based on the first-order shear deformation theory (FSDT), which assumes a single rotation angle for the whole cross-section and a quadratic distribution for coupled electric potential in piezoelectric layers. Shear coefficient is introduced to correct the effect of transverse shear strain on shear force and the electric displacement integration. Static and free vibration analyses of simply-supported bender elements are carried out for the sensor function. The results illustrate the high accuracy of the present model compared with the exact 2D solutions.

Optimal Control of a Beam with Discontinuously Distributed Piezoelectric Sensors and Actuators

因为它的轻重量，宽带，和能适应的性质，聪明的材料广泛地在灵活结构的活跃颤动控制(AVC ) 被使用了。基于一一阶砍变丑理论由联合电、机械的操作， 4 节点有为概括排水量的自由的 24 度和自由的一电的潜在的度的四边的压电的合成元素每压电的层被导出。有不连续地分布式的压电的传感器和致动器的一根横梁的动态特征被介绍。一个线性二次的管理者(LQR ) 反馈控制器被设计用高度在州的空间压制横梁的颤动精确直接(HPD ) 集成方法。

基于砂土界面剪切试验的自传感压电土工电缆监测效果评价

近年来,基于分布式的路堤边坡内部变形实时监测技术受到了学者们的广泛关注和研究,然而由于技术、成本、场景等因素的限制,目前还没有一种技术可以完全实现大面积应用。对此,测试了一种基于压电效应和阻抗应变效应的自传感压电土工电缆(sensor-enabled piezoelectric geocable,SPGC),并通过获得SPGC-砂土界面剪切试验中产生的阻抗及电压信号评价其监测效果。试验结果表明,剪切位移-剪应力曲线与剪切位移-归一化阻抗曲线具有良好的对应关系(可检测剪切带土体应变软化的发展);有效值电压随着剪切速率的增大而成正比例关系增大(可量化剪切带的土体位移速率);随着法向应力和相对密实度的增大,有效值电压逐渐增大,归一化阻抗逐渐减小(可反映剪切带土中应力的变化);通过双线性模型描述剪切位移-归一化阻抗的相互关系的效果较好。SPGC可以实现路堤边坡滑坡灾变定位和前兆识别,有望为路堤边坡施工和运维监测提供一种分布式、低成本、自驱动的解决方案。

免标定壁面剪应力测量技术研究

剪应力传感器的标定是一个极其复杂且易受环境影响的过程。因此,免标定壁面剪应力测量技术是一个很有前景的研究方向。该文介绍这种无需标定即可测量局部壁面剪应力大小和方向的技术的研究状况。该技术使用2个尺寸相同的双层热膜传感器,彼此靠近并垂直放置,形成V形。实验证明,该方法能够以合理的精度测量壁面剪应力矢量,且无需标定。

光机材料与光纤振动传感器连接力学可靠性研究

针对不同的典型空间相机光机结构材料,研制典型空间相机用光机材料试块,能够有效代表现有相机主要光机结构组成和光纤振动传感器安装对象。设计相关试验工装,通过工装连接进行拉伸强度和剪切强度试验,获得其强度破坏参数。从而进行连接工艺强度研究,验证连接力学工艺可靠性。以确保实现传感器与空间相机结构的有效连接,完成极限力学环境试验考核,为传感器在后续型号中的应用提供参考。

基于MEMS传感器测试的黏性土-混凝土力学特性研究

为更好地测量桩与土界面处的孔隙水压力和径向土压力,在混凝土试块表面安装硅压阻式微电子机械系统(MEMS)传感器,安装方式为开孔嵌入式。通过大型直剪实验系统对不同湿度条件下,含水率分别为18%、20%、25%和28%的粉质黏土-混凝土界面进行力学性能研究,分析了粉质黏土-混凝土界面的抗剪强度特性受水分特性的影响。对混凝土界面性能进行实验研究,结果表明,随着黏性土含水率的增大,界面抗剪强度、剪切破坏位移和界面残余剪切应力均呈先增大后减小趋势,含水率在20%~28%存在一个最优含水率使得界面抗剪特性最优。由此可知,粉质黏土-混凝土界面的抗剪强度特性受含水率影响十分明显,实验结果可为静压桩的工程实践提供借鉴与参考。

正弦余弦算法支持向量回归在MEMS剪应力传感器温度补偿中的应用

为解决电容式微机电系统(Micro-electromechanical system,MEMS)剪应力传感器输出信号随工作环境温度变化产生漂移的问题,提出了基于正弦余弦算法的支持向量回归(Sine cosine algorithm-support vector regression,SCA-SVR)温度补偿算法。首先,利用SVR对传感器温漂进行补偿;其次,基于SCA对SVR的超参数进行优化;最后,将所提出的SCA-SVR温度补偿算法与广泛应用的粒子群支持向量回归(Partical swarm optimization-support vector regression,PSO-SVR)算法进行实物实验对比。结果表明,基于SCA-SVR的温度补偿算法能够有效地对电容式MEMS剪应力传感器的输出温漂进行补偿,SCA-SVR算法补偿后的传感器输出信号与整定值间的相关系数提高至0.9996,均方根误差降低至0.0099 mV,比PSO-SVR算法补偿后的结果降低了一个数量级。

浮动元件壁面剪切应力传感器研究进展

介绍了浮动元件的类型和浮动元件壁面剪切应力测量的方法,阐述了基于浮动元件的电容式、压阻式和光学式壁面剪切应力传感器的基本原理和研究现状,分析了上述3种类型的浮动元件壁面剪切应力传感器的优缺点,指出可通过优化浮动元件与传感器封装件之间的移动间隙以及浮动元件与被测面间的平齐度来提升浮动元件壁面剪切应力传感器的性能。展望了浮动元件壁面剪切应力传感器在湍流测量、判断边界层转捩、维护飞行器安全和优化飞行器结构等领域的发展方向,提出未来可通过发展MEMS技术、优化传感器后端处理电路和温度补偿方式、采用一体化设计加工方式等,进一步提升浮动元件壁面剪切应力传感器的小型化程度、检测壁面剪切应力极低值时的灵敏度和精度、测量的可靠性和准确性。

盐岩冲击特性试验研究

采用 SWT 方法,对盐岩在压剪联合冲击加载过程中的力学特性进行研究,通过跟踪材料动态损伤过程中材料剪切性能的变化,从而确定材料与动态损伤相关的特性。通过对盐岩在压剪联合作用下的不同速度的冲击试验研究,结果显示,当冲击速度高于 200 m/s 时,盐岩材料很快进入破坏阶段;当冲击速度为 70～200 m/s 时,盐岩材料处于动态损伤状态。并第 1 次发现一个非常有意义的现象,即与一般的脆性材料的冲击完全不同的是,盐岩在压剪联合冲击过程中除了常规的 4 道冲击波外,在卸载压缩波到来之前,还有 1 道卸载剪切波。

MEMS壁面剪应力传感器阵列水下标定实验研究

壁面剪应力的精确测量对于研究水下物体边界层流动、寻求有效的减阻增效措施至关重要。MEMS壁面剪应力传感器的标定首先是最基本的静态标定,其决定了其测量的精度和数据的可信度。本文在分析已有标定方法的基础上研发1种新型水下壁面剪应力给定装置,并采用数值方法计算分析不同流速下的壁面剪应力给定条件,进而设计壁面剪应力传感器静态标定方案,开展了一种MEMS热膜式壁面剪应力传感器阵列的水下静态标定实验,获得了各传感单元的标定系数。

架空输电线路覆冰监测用FBG拉力传感器的研制

相对于传统的电阻应变片,光纤布喇格光栅(fiberbragggrating,FBG)传感器具有抗电磁场干扰、绝缘性能好、寿命长等优点,可以可靠地用于架空输电线路的覆冰测量。为了提高已有的FBG柱式称重传感器性能,更好地监测导线覆冰情况,研制了用于耐张塔处的光纤布喇格光栅S型拉力传感器,结合光纤布喇格光栅倾角传感器,可以测量导线覆冰厚度、张力、弧垂等多项重要参数。所研制的光纤布喇格光栅S型拉力传感器由弹性体和FBG传感器两部分组成。其中弹性体采用S形剪切式外形,工字形截面。在弹性体两侧腹板处分别成±45°粘贴FBG传感器。弹性体受力后,在两侧腹板处可相应地产生拉压成双的主应变,两FBG波长值相减,不用额外补偿措施即能消除FBG温度与应变的交叉敏感问题。实验室研究表明,所研制的光纤布喇格光栅S型拉力传感器线性度较高,非线性误差为0.76%,灵敏度为0.0495pm/N,分辨率为20.2N/pm,精确度为1.2%,相对于实验室以前研制的FBG柱式称重传感器,非线性误差降低了一半,精确度提高了一倍,工作稳定。