应变片测量电路
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图1 电子秤平剖图 1 台面壳体2均压框架3电阻应变片4弹性体 5补偿电阻6可调支撑脚7底座如图1所示,底座通过贴有电阻应变片的双孔型等强度弹性体梁与均压框架相接,均压框架用螺钉与壳体相联。
弹性体是应变式力传感器将力转换为应变量的关键部件。
研究结果表明,双孔梁弹性体按刚架计算比按平行梁计算精确,而且桥路输出和载荷之间的线形好、灵敏度高。
非线性和灵敏度与竖梁的长度和刚度无关。
由于采用陶材料设计制作弹性梁,其灵敏度结构系数不仅取决于弹性体结构形式和应变区的选择,而且和陶瓷材料的微结构、质量及机械强度等因素密切相关。
为此,进行了双孔梁的应力分析、抗冲击载荷分析、额定载荷计量等,并用计算机进行了有限元分析。
经模拟验证分析,选用图1a所示的双孔梁结构形式。
该梁的应力分布均匀对称,其应力最大点在弹性梁的最薄偏离两端处。
根据图1a所示的结构形式: ε=M/W.E (1)式中:ε为应变量;M为弯矩;W为抗弯模数;E为弹性模量。
对于这类应变式弹性体上的全等臂电桥,其输出电压V0和桥压V i有如下关系: V0=G F.ε.V i (2)式中:G F为应变电阻的应变系数。
将式(1)代入式(2),可得: V0=G F.M.V i/W.E (3) 对于矩形截面,W=1/6b.h2式中:b为弹性体承载面宽度;h为弹性体承载梁厚度。
由A—A剖面分析,负荷F必须由一对剪力F/2与之平衡。
若取一应变电阻进行分析,F/2对应变电阻中心点的弯距为M0: M0=F(L/2-X)/2 (4) 以式(4)代入式(3),可得: V0=3F(L/2-X)G F.V i/b.h2.E (5) 由式(5)可见,双孔梁的桥路输出和载荷F之间具有良好的线形,而且灵敏度高。
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Speech at the Conference on the system of government offices in the city around the development of servicefunction to create a new situation in the work of the Office of the city's system of Government--speech at the Conference on the system of government offices in the city This system of government offices working in the city's main task is to study Government systems of administrative supervision, administrative information, administrative reception and information technology issues. For the meeting, the City Mayor Ma has made important instructions, the Municipal Government Office fully prepared brewing, combined with practical work to develop the notice on further strengthening the supervision work, the XX, Chief Information interim measures for 2005 and the city's system of Government Administration informatization construction task statement and other documents. 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金属箔式应变片与电桥测量电路实验一金属箔式应变片与电桥测量电路本实验包含两个部分:(1) 单臂电桥说明金属箔式应变片及单臂直流电桥的原理和工作情况,(2) 单臂、半桥、全桥特性比较。
实验1.1 单臂电桥一、实验原理:况。
本实验说明金属箔式应变片及单臂直流电桥的原理和工作情应用应变片测试时,应变片牢固地粘贴在被测件表面上。
当被测件受力变形时,应变片的敏感栅随同变形,电阻值也发生相应的变化。
通过测量电路,将其转换为电压或电流信号输出。
电桥电路是非电量电测最常用的一种方法。
当电桥平衡时,即 R1=R2 、R3=R4 ,电桥输出为零。
在桥臂 R1 、 R2 、 R3 、 R4 中,电阻的相对变化分别为? R1/R1 、? R/R 、? R2 , R2 、? R/3R3 、? R4/R4 。
桥路的输出与当使用一个应变片时,当使用二片应变片时,如二片应变片工作,差动状态。
则有用四片应变片组成二个差动对工作,R1=R1=R3,R4=R ,于是,所以,由此可知,单臂,半桥,全桥电路的灵敏度依次增大。
二、实验所需部件直流稳压电源、电桥、差动放大器、测微头,电压表(毫伏表)三、实验步骤1. 按图 1 所示将全部部件连接其中差动放大器和毫伏表使用前都要调零,(电压表可不必调零)。
毫伏表放在500mV 一挡比较合适,图1 电桥电路连接2. 将差动放大器调零方法是用导线正负输入端连接起来,然后将输出端接到毫伏表的输人端,调整差动胶大器的增益旋钮,使增益尽可能大,同时调整差动放大器上的调零按钮,使毫伏表指示到零,调好后旋钮就不可再动。
3. 确认接线无误时开启电源4. 在测微头离开悬臂梁,悬臂梁处于水平状态的情况下,通过调整电桥平衡电位器,系统愉出为零。
5. 装上侧微头,调整到系统输出为零,此时测微头读数为梁处于水平位置( 自由状态),然后向上旋动测微头,从此位置开始,记下梁的位移与电压表指示值,继续往下悬臂梁,一直到水平下 7 一 8mm为止,并记下对应位置的电压表的值。
一、直流电桥的输出电压•应变片或电阻元件作为电桥桥臂。
•多种形式选择:R 1;R 1和R 2;R 1 -R 4,其余为精密无感电阻。
•A 、C 为电桥的输入端,B 、D 为电桥的1. 直流电桥的基本结构输出端。
•E 为直流源。
2. 电压桥(1)什么是电压桥•应变片通常后接放大电路为高输入阻抗。
•测量端通常工作在小电流状态,主要是电位差起作用。
•近似认为输出端开路,是为电压桥。
(2)电压桥的输出电压及平衡条件设E 恒定,分支电流为1,212EI R R =+3,434EI R R =+R 1、R 4的电压降为1AB A B ER U U U =-=12R R +434AD A D ER U U U R R =-=+则B 、D 间的电位差U 为14123413241234()()()D B AB AD R R U U U U U ER R R R R R R R ER R R R =-=-=-++-=++3. 电桥负载为有限值时的情形依据等效电源原理(戴维南定理)13241234()()R R R R U ER R R R -=++等效电压源电源内阻U RR LB DI L U L 123401234R R R RR R R R R =+++输出电流(负载电流)0L L UI R R =+P 1P补偿片与工作片分别安装在构件上、下表面并平行测量受弯、拉组合载荷梁的梁的表面弯曲应变。
2112,M P P εεε=-=弹性元件受到偏心压力,欲测量仅由压力引起的构件表面应变。
12,P P P εε==313, P P M εμεεμε=-=-)])]2121T r EM πεμ=+枚应变片,沿圆轴母线±45︒角对称布置,采用全桥接法234T T T M M M εε==-=34P P Pεεε===3444)()]T M M P M εεε-++需要考虑测量导线和应变片分布电容的影响。
创新教育科技创新导报 Science and Technology Innovation Herald128在传统的实验教学中,传感器原理是一门理论性非常强的课程[1-2],为了使学生更好地掌握每种传感器的原理,教学中都配套相应的实验。
但是目前学生主要根据实验指导书进行验证性实验,实验操作训练不足,创新能力难以提升[3]。
事实上,实验中以及实际测量中的应变是极其微小的,传统的测量仪器使用的测量方法和电路精度很差,只能作为尝试型的实验,无法满足高精度的测量。
而现在有更多的教学选择虚拟仪器来模拟应变的测量过程[4-5]。
但是这样让学生更缺乏对传感器和相应测量电路的深刻认识。
针对以上问题,该文提出一个高精度的电阻应片变桥式电路测量方法,由此设计了一个分辨率为0.1 g 的高精度电子秤,来测量应变的线性程度,并把该方法应用到传感器原理的实验教学中。
该设计由以12 V电源供电的电源模块、高精度的差放与模数转换模块、ATm e g a128A 芯片为主的运算模块及键盘输入与显示模块等模块构成。
该设计可以实现高精度测量,正确计算与显示电子秤的金额且能实现去皮等功能,满足0~500 g 测量量程范围内误差小于0.5 g。
1 电阻应变片桥式电路原理电阻应变片能将力学量转变为电学量是利用了金属导线的应变——电阻效应。
金属导线的电阻R与其长度L成正比,与其截面积A成反比,即:LR A(1)式中是导线的电阻率。
DOI:10.16660/ k i.1674-098X.2016.21.128电阻应变片桥式电路原理及课程实验设计吴迪 周长伟 伍远博 沈成 冯灿 江均均 袁宇(苏州大学物理与光电能源学部 江苏苏州 215006)摘 要:笔者设计了一个高精度的电阻应变片桥式测量电路。
系统把12 V直流电源转换为5.5 V,再转换为各个芯片工作需要的5 V和3.3 V电压,由TL431芯片供给一个2.5 V基准电压源从而保证测量电压高稳定性。
电阻应变片的放大电路全文共四篇示例,供读者参考第一篇示例:电阻应变片是一种可以根据外部力变化而改变电阻值的传感器元件,常用于测量应变、压力、力等物理量。
在很多工业领域中,电阻应变片都扮演着重要角色。
为了提高其测量精度,我们常常需要设计一些放大电路来放大电阻应变片产生的小电信号。
在设计电阻应变片放大电路时,我们需要考虑以下几个方面:第一,电阻应变片的工作原理:电阻应变片的电阻值会随着外部力的变化而发生微小变化。
这个变化可以通过电路测量得到,但通常是非常微弱的信号。
因此需要一个放大电路来放大这个信号,以便更精确地测量。
第二,放大电路的选择:在选择放大电路时,一般会考虑到电源电压、放大倍数、带宽等因素。
常用的放大电路包括运放放大电路、差动放大电路等。
电阻应变片的连接方式:电阻应变片通常会以全桥方式连接到放大电路中。
全桥连接可以最大程度地利用电阻应变片的变化,提高测量精度。
第四,放大电路的稳定性:放大电路的稳定性对测量精度也有很大影响。
因此在设计放大电路时,需要注意电路的稳定性,避免出现漂移、噪音等问题。
为了更好地理解电阻应变片的放大电路,我们可以通过一个具体的实例来进行详细说明。
假设我们有一个电阻应变片,其电阻值在外部力作用下发生微小的变化,我们需要设计一个放大电路来放大这个变化信号,并通过测量得到具体数值。
我们选择一个运算放大器作为放大电路的核心元件。
运算放大器有很高的输入阻抗和放大倍数,非常适合放大微弱信号。
然后,我们需要设计一个合适的反馈网络来确定放大倍数。
通过选择合适的电阻和电容值,可以确定放大倍数,并且保证电路的稳定性。
我们通过示波器或者多用表来测量放大电路输出的信号,从而得到电阻应变片的变化数值。
通过以上设计过程,我们成功地设计出了一个电阻应变片的放大电路,并可以准确地测量出电阻应变片的变化值。
这样的放大电路不仅提高了测量精度,还可以应用在各种工业领域,为生产和制造提供准确的数据支持。
电阻应变片的放大电路设计是一个复杂而又重要的工作。
台州学院物电学院电气自动化实验一应变片桥式测量电路研究实验思考题1、本实验电路对直流稳压电源和对放大器有何要求?答:直流电源要稳定;放大器零飘要小。
2、根据所给的差动放大器电路原理图,分析其工作原理,说明它既能作差动放大,又可作同相或反相放大器。
答:将被电阻接在单桥的被测桥臂上,调节另三个桥臂(比例臂和比较臂)上的已知电阻,使电桥平衡(检流计指零),以此测得被测电阻的大小。
通过调节两端电压可将其当作同相或反相放大器,调节W1可以实现差动放大。
当正输入端接地负输入端作输入则就成反向放大器反之就成正向放大器,对输入端阻抗要求同原要求一样即近似为0,在技求可应用CMOS低阻抗模似开关进行切换。
3、述应变片直流单臂电桥系统实验结果产生非线性误差的原因。
由实验原理我们可以知道,运用应变片来测量,主要是通过外界条件的变化来引起应变片上的应变,从而可以引起电阻的变化,而电阻的变化则可以通过电压来测得。
而实际中,电阻的变化与应变片的应变的变化不是成正比的,而是存在着“压阻效应”,从而在实验的测量中必然会引起非线性误差。
实验二移相器和相敏检波器电路性能实验思考题1、根据实验结果,可以知道相敏检波器的作用是什么?移相器在实验线路中的作用是什么?答:相敏检波器的作用:具有鉴别调制信号相位和选频作用。
移相器的作用:将信号的相位移动一个角度。
2、当相敏检波器的输入与开关信号同相时,输出是什么极性的什么波,电压表的读数是什么极性的最大值?答:当相敏检波器的输入信号与开关信号同相时,输出为正极性的全波整流信号,电压表指示正极性方向最大值。
实验三电涡流式传感器实验思考题1、电涡流传感器的量程与哪些因素有关,如果需要测量±5mm的量程应如何设计传感器?答:与电涡流传感器能够产生磁场大小有关,还与被测体的材质有关;如果要测量正负5伏的量程让传感器中空被测物体靠近一侧是会远离另外一侧从而保证测量范围。
2、用电涡流传感器进行非接触位移测量时,如何根据量程使用选用传感器。
应变片的工作原理
应变片是一种用于测量物体表面应变的传感器,它可以将物体
受到的应变转换为电信号,从而实现对物体应变的测量和监测。
应
变片的工作原理基于材料的电阻变化和应变之间的关系,通过测量
电阻值的变化来确定物体受到的应变量。
应变片的工作原理可以分为以下几个步骤:
1. 材料特性:应变片通常由导电材料制成,如金属薄膜或碳纳
米管等。
这些材料具有特定的电阻特性,当受到外力作用时,材料
会产生应变,导致电阻值发生变化。
2. 安装固定:应变片被安装在需要测量应变的物体表面上,通
常使用胶水或粘合剂将其固定在物体表面。
当物体受到外力作用时,应变片会随之产生应变,从而改变其电阻值。
3. 电路连接:应变片的两端连接到测量电路中,通常是一个电
桥电路。
电桥电路通过对比应变片的电阻值和参考电阻值来测量应
变片的电阻变化,从而确定物体受到的应变量。
4. 电信号输出:测量电路会将测得的电阻值转换为电信号输出,通常是模拟电压信号或数字信号。
这些信号可以用于实时监测物体
的应变情况,也可以通过数据处理和分析得到物体的应变分布图和
应变变化趋势。
应变片的工作原理基于材料的电阻特性和应变之间的关系,通
过测量电阻值的变化来确定物体受到的应变量。
它具有灵敏度高、
响应速度快、精度高等优点,因此被广泛应用于工程结构、材料测试、医疗设备、航空航天等领域的应变测量和监测中。
希望通过本
文对应变片的工作原理进行介绍,能够让读者对其原理有更深入的
理解。