电桥法测杨氏模量的实验研究

本文引入了电桥法测量杨氏模量,用自制平行板电容器对传统的实验装置进行改进,用电容的变化来表征微小位移的变化,通过实验原理、误差分析,结合测量结果,由此给出了一种测量杨氏模量的新的方法.     

开尔文电桥电路测量材料杨氏模量系统的实验设计与开发

本实验主要是应用开尔文电桥电路测微小电阻的原理,根据钢丝材料在受力的作用下,钢丝长度发生微小变化时其电阻也随之变化的关系,由相关理论推导出测量钢丝材料杨氏模量的计算公式,并提出了一种测量材料杨氏模量的方法。     

直流双臂电桥在测定金属杨氏模量中的应用

本阐述了QJ44型直流双臂电桥的适用范围及测量原理,将对长度及长度增量表示的金属杨氏模量公式换算成以电阻及电阻增量表示的杨氏模量公式。从而通过测量金属丝拉伸前后的电阻值,计算出金属杨氏模量。     

金属的杨氏模量测定研究

金属丝在拉伸力的作用下长度会发生微小变化,金属丝长度的微小变化会使其电阻同时发生微小改变,利用双臂电桥测量低阻值电阻的原理测金属丝电阻的微小变化量,再通过相应的公式求得被测金属丝的杨氏模量,该方法简便,测量准确.     

基于CSY-998型传感器研究钢丝杨氏模量

基于传统的用拉伸法测量钢丝的杨氏模量实验,利用CSY-998型传感器平台研究钢丝杨氏模量,一方面是对电桥法中电阻式应变传感器的实际应用,另一方面通过与其它实验方法的比较,对学生拓展思维、创新实验也起到了较好的作用。     

用开关代替灵敏电流计测量电流表的内阻

提出一种测量电流表内阻的方法,用电流表作为桥臂电阻并监测电流大小,在电桥中点,用开关通断改变电桥连接状态,通过桥臂电流变化判断电桥平衡.     

探讨热敏电阻温度计的制作及其要领

电桥测电阻实验是高校普通物理教学中的传统电学实验之一.目的是让学生验证电桥平衡原理,掌握电桥的使用方法.实验中学生要做的就是反复多次测量电阻阻值,实验内容比较简单,很快就能完成.针对这种情况,我们对此实验做了适当的改进.让学生在熟悉电桥的使用方法后,利用电桥的功能及热敏电阻的特性,制作一个简易的热敏电阻温度计.热敏电阻是一种广泛应用于温度测量、温度控制、温度补偿等方面的元件,当其温度发生微小变化时,它的阻值就要发生相应变化.通过这个小制作,不仅充实了电桥实验的内容,也可以使学生了解热敏元件的一些特性,同时也提高了学生做实验的兴趣.     

利用等厚干涉测量钢丝的杨氏模量

测量杨氏模量常采用光杠杆法进行测量。而利用等厚干涉的方法可以比光杠杆法更精确地测出钢丝形变的变化量。目前利用等厚干涉测量杨氏模量的实验中多需借助显微镜进行观察及使用电脑对图像进行处理。本文提及的实验方法既可以用电脑进行图像处理,也可以直接用肉眼观察条纹的变化,使实验变得简单易行且精度也比较高,并能满足不同层次的数据处理的需要,可以作为一项综合性实验纳入大学物理实验中。     

光的衍射法测量杨氏模量

拉伸法测量金属丝杨氏模量的关键是如何测准金属丝在拉力作用下的微小伸长量。本文利用光的衍射法可以较精确地测量长度变化这一特点，对钢丝的杨氏模量进行了测量，给出测量杨氏模量的一种新方法。     

电阻性测量电桥的误差分析

一、引言测量电桥(Measurement bridge)指至少有一个桥臂是敏感元件的惠斯登电桥。这种电桥,在平衡时输出电压为零,此时规定为输出起始位;随着被测量变化引起敏感元件值的改变,从而电桥平衡破坏,桥输出不为零,被测量变化大,输出也大,这就是不平衡电桥的测量原理。     

Measurement of adhesion energies and Young's modulus in thin polymer films using a novel axi-symmetric peel test geometry

We present a novel method of probing adhesion energies of solids, particularly polymers. This method uses the axi-symmetric deformation of a thin spincast polymer membrane brought into contact with a flat substrate to probe the work of adhesion. The use of a thin membrane minimizes uncertainty in the radius of contact, while the use of spincast films provides very smooth surfaces by means of a very simple method. The experimental profile of the deformed membrane shows good agreement with the expected logarithmic profile. The experimental setup enables the measurement of Young's modulus and the solid-solid work of adhesion for thin films. The value obtained for Young's modulus of polystyrene (PS) was found to be in agreement with other conventional measurement techniques. In addition, measurement of the work of adhesion at the PS/silicon oxide interface was possible. The apparatus is well suited to studying the dependence of Young's modulus, work of adhesion and fracture energy on membrane thickness, temperature, pulling rate, and ageing of the interface, and can readily be modified to study biologically relevant samples.     

Influence of static compression on mechanical parameters of acoustic foams

The modification of elastic properties of compressed acoustic foams is investigated. The porous sample is first submitted to a static compression and then to a dynamic excitation of smaller amplitude, corresponding to acoustical applications. The static compression induces the modification of the dynamic elastic parameters of the material. This work focuses on Young's modulus. The variation is measured with two different experimental methods: The classical rigidimeter and an absorption measurement. The effective Young's modulus is directly measured with the first method and is indirectly determined through the quarter-wave length resonance of the frame with the second one. The results of the two measurements are compared and give similar tendencies. The variation of the dynamic Young's modulus as a function of the degree of compression of the sample is shown to be separated in several zones. In the zones associated with weak compression (those usually zones encountered in practice), the variation of the effective Young's modulus can be approximated by a simple affine function. The results are compared for different foams. A simple model of the dependency of the Young's modulus with respect to the static degree of compression is finally proposed for weak compressions.     

Effect of a rippling mode on resonances of carbon nanotubes

A recent study determined the Young's modulus of carbon nanotubes by measuring resonance frequency and using the modulus-frequency relation resulting from the linear vibration theory. It leads to the report that the Young's modulus decreases sharply, from about 1 to 0.1 TPa with the diameter D increasing from 8 to 40 nanometers, and the investigators attributed this decrease to the emergence of an unusual bending mode during the measurement that corresponds to rippling on the inner arc of the bent nanotubes. The nonlinear analysis presented in this paper that captures the rippling mode suggests that the effective Young's modulus can indeed decrease substantially with increasing diameter, and that the results from the classical linear theory may be invalid in such measurements.     

衍射法测量金属丝的杨氏模量

本文提出了一种新的测量金属丝杨氏模量的方法--夫琅禾费单缝衍射法.平行光遇到由金属丝被拉伸形变而形成的单缝,产生衍射,用CCD光强分布测量仪接收衍射光信号,用示波器定标方法测量衍射角,可以精确计算金属丝的杨氏模量.最后与普通光杠杆放大法比较,对可能引入的误差来源做了分析,结果证明,本方法测量精度更高、相对误差更小.     

新型杨氏模量自动测量仪的探索与实践

主要介绍了根据动态法测量原理设计的新型杨氏模量自动测量仪,此仪器创新性地采用全自动扫频技术,实现了金属材料杨氏模量的全自动测量,并且增加了虚假共振的判断和品质因素的测量,提高了测量结果的可靠性.     

Measurement of the Elasticity of Biological Soft Tissue of Finite Thickness

Elasticity is of profound significance to evaluating the function of a biological soft tissue.When the elasticity of a tissue is macroscopically changed,it means that the biological function of the tissue is abnormal and some disease or injury may occur.In the present work,an elastometer is developed to measure the elasticity of biological soft tissues.The measurement is based on the indentation method and the force is measured by the bending of the cantilever.The force-indentation data of the soft tissue is experimentally measured by this elastometer and Young's modulus of the tissue is calculated using the Hertz-Sneddon model.For comparison,a numerical model for the indentation method is established using the finite element method.The difference between the actual modulus and the measured modulus is discussed.The effect of the thickness of the specimen on the measurement is investigated.Young's moduli of beef,porcine liver and porcine kidney are experimentally measured.The results indicate that our elastometer is effective in measuring Young's modulus of a soft tissue quantitatively.     

Effect of Young's modulus evolution on residual stress measurement of thermal barrier coatings by X-ray diffraction

Subjected to thermal cycling, the apparent Young's modulus of air plasma-sprayed (APS) 8 wt.% Y₂O₃-stabilized ZrO₂ (8YSZ) thermal barrier coatings (TBCs) was measured by nanoindentation. Owing to the effects of sintering and porous microstructure, the apparent Young's modulus follows a Weibull distribution and changes from 50 to 93 GPa with an increase of thermal cycling. The evolution of residual stresses in the top coating of an 8YSZ TBC system was determined by X-ray diffraction (XRD). The residual stresses derived from the XRD data are well consistent with that obtained by the Vickers indention. It is shown that the evolution of Young's modulus plays an important role in improving the measurement precision of residual stresses in TBCs by XRD.     

掺杂单晶硅纳米薄膜杨氏模量的多尺度理论模型

硅纳米材料物理性能的研究对其在半导体技术中的应用是十分重要的. 而掺杂有利于改善硅纳米材料的物理特性, 提高应用价值, 所以本文基于半连续体模型运用Keating形变势, 通过模型计算, 研究了不同位置及不同掺杂浓度的单晶硅纳米薄膜[100]方向的杨氏模量, 分析了掺杂浓度及掺杂位置不同时硅膜杨氏模量与膜厚关系, 结果表明, 与纯硅膜杨氏模量相比, 不同位置的掺杂对硅膜杨氏模量的影响并不明显, 不同浓度的掺杂对硅膜杨氏模量的影响较小. 而随着硅膜厚度的不断增加, 掺杂硅膜杨氏模量与纯硅膜杨氏模量的变化趋势一致, 特别是较小尺寸时的硅膜杨氏模量变化较大. 说明影响硅膜杨氏模量的主要因素是硅膜厚度. 该计算结果对研究硅纳米材料的其他力学特性有一定的参考价值, 也为进一步研究掺杂对纳米硅材料力学性能的影响提供一种全新思路.