“三线摆”测物体定轴转动惯量的实验原理  

The Experimental Principle of Measuring the Moment of Inertia of the Fixed Axis of the Three Wire Pendulum

作　　者：石大立[1] 刘春晖[1] 吴艳阳[1] 

机构地区：[1]武汉工程大学机电工程学院力学教研室,湖北武汉430073

出　　处：《装备制造技术》2016年第4期13-17,共5页Equipment Manufacturing Technology

摘　　要："三线摆"实验中,摆动周期由测量摆盘系统的转动惯量决定。只要摆盘上放置物体,测量摆盘系统转动惯量就会改变,则其摆动周期随之改变。因此,实验求取:两个圆柱及待测物对中心轴转动惯量和时,必须分别做两个摆盘空载时、两个摆盘加载被测物后的扭振实验各两次;再根据实验结果,间接获得被测物转动惯量;并且由实验数据表的项数据,可判断实验结果的准确性;最后再运用插入法求得零件转动惯量。特别运用两组不同的学生实验数据来验证该实验的原理。对实验的误差分析,说明提高扭振周期的测量精度,可显著提高实验结果的准确性。"三线摆"实质是振动系统,属于单自由度无阻尼自由振动问题,因此本文着重从理论方面讨论了单自由度系统的自由振动。In the experiment of three wire pendulum,the swing period is determined by the moment of inertia of the measuring pendulum system. The moment of inertia of the measuring pendulum system will be changed whenever an object is placed on its wobble-plate,so its swing period will be changed then. Therefore,when you do experiments to obtain the moment of inertia of the two cylinders rotating about the central axis and the moment of inertia of the object to be tested rotating about the central axis,two kinds of the torsional vibration experiments must have been done separately four times when each wobble-plate is unloaded and after each wobble-plate is loaded the object. According to the results of these experiments,the moment of inertia of the object to be tested is obtained indirectly. The accuracy of experimental results can be judged by the data itemof the experimental data table. Then the moment of inertia of the part is finally obtained by applying the method of inserting. In particular,the principle of the experiment is verified by using the experiment data of two different groups of students. Error analysis of the experiment shows that improving the measurement accuracy of the swing period can significantly improve the accuracy of the experimental results. In essence, three wire pendulum is a vibration system,belonging to the problem of free vibration of a single freedom degree and undamped system,hence this paper discusses the free vibration of a single degree of freedom system emphatically from the aspects of theory.

关 键 词：转动惯量 三线摆 扭振周期 固有频率 阻尼 

分 类 号：O313.3[理学—一般力学与力学基础]