弹性钢板应力应变实验报告

《应变片测弹性钢板弯曲应力》实验报告院系:机电学院姓名：俞林学号：S310070077指导教师：马洪文日期：2011年1月2日一、实验目的：掌握测量桥式电路的应用，了解应变片的应变原理，了解弹性钢板弯曲应力变化规律，将不同厚度的弹性钢板弯曲应力变化规律进行对比。二、实验设备：电阻式应变片，半桥式电路板，称陀，弹性钢板，HH1713双路直流稳压电源，实验机架(台钳与滑轮)，万用表。三、实验原理：不同受力方向的两片应变片接入电桥作为邻边，电桥输出灵敏度提高，非线性得到改善。当两片应变片阻值和应变量相同时，其桥路输出电压Uo2=EKe/2。四、实验内容：制作半桥式电路板1).应用Protel99SE软件绘制电路图。3).电路板的调试。

电阻应变片的粘贴本实验是在弹性上下个表面对称位置贴一片电阻应变片。1）.准备工作：（1）测点表面打光为了使电阻应变片能准确地反映悬臂梁被测点的变形，必须使电阻应变片和测点表面很好地结合，不发生任何滑移和阻碍变形的现象。为此，必须先用砂纸清除测点表面的油垢、铁锈等，不允许有沟痕并使打磨条纹与电阻应变片贴片方向成450,应使表面粗糙度为Ra3・2左右，不应过分粗糙，也不应过分光滑。然后，用酒精棉球将测点附近基本擦干净。（2）（2）划基准线以测量点为中心用划针划十字线。（3）清洁表面用蹑子夹取棉花球，沾酒精等清洗溶液仔细擦洗测点表面，以棉花球不见污物为止。2）.贴片：（1）取片就位待测点表面酒精晾干后，将502粘合剂均匀地涂在测点表面；用蹑子将电阻应变片取出,对准事先划好的十字基准线贴在测点上。（2）挤压在电阻应变片表面盖上吸水纸，轻轻挤出余胶，使贴好的电阻应变片平直且下面没有气泡。（3）焊接导线用胶带纸将电阻应变片的引线和悬臂梁绝缘。将四根长度和粗细一样的导线分别焊接在贴于弹性钢板上、卜•表面的两个电阻应变片的四根引线上，并将导线固定在弹性钢板上。应变片贴中间的弹性钢板应变片贴在根部的弹性钢板电源3.加载称舵进行应力测量，并用万用表记录电压数据如卜•:质呈(kg)00.20.50.711.21.51.722.22.52.733.23.53.7误差1电压(mv)-84123439623823933111711891283134214011454149715221540157710.02电压(mv)-6315144S64085195010991185128813451396145914921518155815727.83电压(mv)-6314545963293996011211208127713421428146214991535155515688.6L=90mm,S=0・5mm（应变片贴在中间）表1

平均电-70139.744S.7631.7837.7947.71112311941282713431408314583149615251551157238.8压（mv）L=80mm,S=0・5mm（应变片贴在中间）表2质呈(kg)00.20.50.711.21.51.722.22.52.733.23.53.7误羞1电压(mv)-6721658879210511206135S14711574161516991723174917761807182119.92电压(mv)-662115898171014115413531430153315S216491683173917721807183222.63电压(mv)-6221759379710161174134914251514157616351688173017491797182612.7平均电压（mv）-65214.7590802102711781353.3144215403159116611698173931765.71803.71826.31S.9L=80mm,S=0・5mm（应变片贴在根部）表3质M(kg)00.20.50.711.21.51.722.22.52.733.23.53.7误差1电压(mv)•5531S8(5810921284144516(5218021874196520922155225123102405243969.22电压(mv)-283257459141234136816151748184S19382038212511012257233(5235521.73电压(mv)-213027199381174135315521(5771S01190420002058210821(552256232953.3平均电压（mv）-34.7315777.3918.31230.713S8.71(509.71742.318411935.72043.32112.721S6.7224423322374.352.0L=60mm,S=0・5mm（应变片贴在中间）表4质虽(kg)00.20.50.711.21.51.722.22.52.733.23.53.7误差1电压(mv)-721384255686998299299801030110111391162117711901202120411.32电压(mv)-4S153421587734831927992104010801119113611601181119412016.73电压(mv)-4215842959373982694099S105510901125114711731188120212077.5

平均电-54149.7425582.7724828.79329901041.7109031127.?114S.311701186.31199312048.7压（mv）L=80mm,S=0・6mm（应变片贴在中间）表5质M(kg)00.20.50.711.21.51.722.22.52.733.23.53.7误差1电压(mv)-1101719532342757270379289497610921140123812581354142611.42电压(mv)-9S26212324442572717S0291899410641118117412941371142613.33电压(mv)-95282163274605697187969219781079114612311276135914058.6平均电压（mv）-10123.7207.7324.7443571712.7796.7911982.7107S.31134.71214312761361.3141911.3L=90mm,S=0・6mm（应变片贴在中间）表6质M(kg)00.20.50.711.21.51.722.22.52.733.23.53.7误差1电压(mv)-11031217367528647811S911026110212361275135414281521156711.32电压(mv)-105322483S0553639809S921053110312611301137414301486154210.53电压(mv)-104322513S65456648049011037109311931302137514261486154111.9平均电压（mv）-106.331.7238.7377.7542650808S94.7103S.71099312301292.71367.714281497.7155011.2L=80mm,S=0・6mm（应变片贴在根部）表7（每次实验间隔时间较长）质虽(kg)00.20.50.711.21.51.722.22.52.733.23.53.7误差1电压(mv)■125-28103177305392497562677745839877944975105611075.22电压(mv)■125-291021933033874895656727548318779509S7105410S05.23电压(mv)」10-26103193307384495564674753847875952990106111015.6

平均电■12027.7102.7187.7305387.7493.7563.7674.3750.7839876.3948.79481057109653压（mv）L=80mm,S=0・8mm（应变片贴在中间）表8质虽(kg)00.20.50.711.21.51.722.22.52.733.23.53.7课差1电压(mv)■163-68211001742363173854465285826417287768428398.42电压(mv)■127-59269S1752443143744595235916627307708468895.13电压(mv)-121-63291051832493353844515186026547247778558906.8平均电压（mv）■137-63.325.3101177.3243322381452523591.7652.3727.3774.3847.67890.676.9L=90nmi,S=0.8nun（应变片贴在中间）表9质虽(kg)00.20.50.711.21.51.722.22.52.733.23.53.7谋差1电压(mv)-593214723130637151958166073882888496S10461115118S8.72电压(mv)•394016324333640751457668174283690298110451145118910.43电压(mv)-344415324431337351258566174S8349039771026110611708.0平均电压（mv）-443&7154239.3318.3383.7515580.7667.3742.7832.78963975.3103911221182.39.1五、实验数据及处理分析：实验测量结果取平均值用MATLAB软件进行最小二乘拟合与上表对应曲线图如下:图图#12001000800GOO400200■2OOo0.512001000800GOO400200■2OOo0.51.53.52、实验中的错误、原因及修改。错误一：在半桥式放大电路由于放人倍数选的过大使输出的电压只有15V左右。原因：由于选取的放人器的供电电压是15V,放人器放人的输出电压不能超过自身的供电电压。修改：更换电阻Rg由50欧改为500欧，由放大1000倍改为放大100倍。错误二：应变片失效。原因：由于先贴应变片，之后在弹性钢板上打孔，打孔时的强烈振动使应变片失效。修改：打孔后重新贴应变片。错误三：测出当弹性钢板没有形变时输出电压有压差，并且很人。原因：应变片引角与弹性钢板相连，弹性钢板有电阻，使测试点不等势而有压差。