利用应变片测量金属弹性模量

MEASUREMENT OF METAL ELASTICITY MODULUS BY STRAIN GAGE

本文给出了金属弯梁的应变与其负载质量的关系及利用应变片和惠斯通单臂电桥中的电流测量金属弹性模量的公式;对利用应变片直接测量应变的方法和利用光杠杆测量驰垂度的方法测量铜棒弹性模量的实验结果进行了比较;讨论了利用应变片直接测量梁的应变的方式测量金属弹性模量的影响因素。本文研究表明:理论上利用应变片和单臂电桥电流可以测量梁的弹性模量;利用应变片和单臂电桥测量物体弹性模量与光杠杆方法的测量结果相差1%,此法测量的准确性好;单臂电桥的灵敏度低且缺少温度补偿功能可使测量结果波动,导致6组测量结果与平均值的最大差异为2.6%,通过对多组测量求平均值,可在很大程度上降低上述因素引起的测量误差。

The relation between tensile strain and the weight load of a bending copper beam and the formula of testing elasticity modulus with a strain gage and current in single-arm Wheatstone bridge were derived in this paper. The elasticity modulus of the copper beam were measured by the strain gage directly and by the optical lever method indirectly. The results were compared and some influence factors were discussed based on the direct measuring meth- od. Studies in this paper show that both of the two methods are effective. There was only 1 difference between the experimental results by using two different methods. However, the accuracy of measurement is better in the direct method by the strain gage. In the indirect method, the lower sensibility and the lacking of temperature compensation of single-arm Wheatstone Bridge were proved to be major factors that lead to errors produced in this paper, where the biggest difference from the average value can be 2.6%. Increasing test times was an effective way to reduce the bias of the results.