综合实验试题C:扭摆法测量材料的切变模量和内耗  

Comprehensive problem C:Measuring shear modulus and internal friction of materials by torsion pendulum method

作　　者：梁飞翔 江波 熊小敏 蔡志岗[1,2] LIANG Feixiang;JIANG Bo;XIONG Xiaomin;CAI Zhigang(School of Physics,SUN Yat-sen University,Guangzhou 510275,China;National Demonstration Center for Experimental Physics Education(Sun Yat-sen University),SUN Yat-sen University,Guangzhou 510275,China;School of Electronies and Information Technology,SUN Yat-sen University,Guangzhou 510275,China)

机构地区：[1]中山大学物理学院,广东广州510275 [2]中山大学物理学国家级实验教学示范中心(中山大学),广东广州510275 [3]中山大学电子与信息工程学院,广东广州510275

出　　处：《物理实验》2024年第6期23-29,共7页Physics Experimentation

基　　金：中山大学本科教学质量工程项目(中山大学教务〔2023〕96号)。

摘　　要：基于葛氏扭摆测量固体材料内耗的实验原理,设计了第9届全国大学生物理实验竞赛综合实验试题C,从命题背景、实验内容和参考答案的角度给出了本届参赛学生的整体表现分析.试题C的实验内容为:通过扭摆法测扭丝的剪切模量及内耗.试题C以简谐振动作为出发点,描述了摆杆在扭丝回复力矩的作用下绕摆杆中心轴做符合简谐振动规律的衰减运动.试题共包含3部分内容:理解实验原理并搭建正扭摆实验装置,以此实验装置为基础搭建出光杠杆测量光路;推导出简谐振动形式下,摆杆的转动惯量与周期的关系并计算出不规则摆杆的转动惯量,利用计算出的摆杆的转动惯量得出扭丝的剪切模量;计算扭丝在特定转动频率下的内耗.Based on the experimental principle of measuring the internal friction of solid materials,the comprehensive problem C of the 9th National College Students Physics Experiment Competition was designed,and the overall performance of the participants was analyzed from the perspectives of proposition background,experiment content and reference answers.The experiment content of problem C was to measure the shear modulus and internal friction of twisted wire by torsion pendulum method.Based on the description of the pendulum,the attenuation motion of pendulum rod around the central axis was analyzed under the action of torsion torque in accordance with the law of simple harmonic vibration.The test consisted of three parts.The first was understanding the experimental principle and building the positive torsion pendulum experimental device,and then building the optical lever measurement optical path based on this experimental device.For the third part,the relationship between the moment of inertia of the pendulum rod and the period in the form of simple harmonic vibration was required to be derived,and the moment of inertia of the irregular pendulum rod was calculated.As well the shear modulus of the torsion wire was obtained from the calculated moment of inertia of the pendulum rod,the internal friction of twisted wire at a specific rotation frequency was calculated.

关 键 词：葛氏扭摆 转动惯量 剪切模量 内耗 

分 类 号：O343[理学—固体力学]