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1.
本文广泛地收集了有关内耗,力学谱,超声衰减方面的专著及会议文集。反映了20世纪在此领域的英文,俄文出版的书籍。也列出了历次国际会议及前苏联,乌克兰,中国的国内会议。文中包括了点缺陷,电,声子,位错,晶界,电畴等诸方面在内的内耗与力学谱工作。  相似文献   

2.
本文广泛地收集了有关内耗,力学谱,超声衰减方面的专著及会议文集.反映了20世纪在此领域的英文,俄文出版的书籍.也列出了历次国际会议及前苏联,乌克兰,中国的国内会议.文中包括了点缺陷,电,声子,位错,晶界,电畴等诸方面在内的内耗与力学谱工作.  相似文献   

3.
文章对内耗与力学谱的基本原理作了简明介绍,并结合几个具体研究实例评述了内耗技术在凝聚态物理和材料科学研究方面的可能应用,最后指出了该领域今后的主要研究课题是发展新的内耗测量方法和技术以及发现新的内耗谱和建立新的内耗理论.  相似文献   

4.
固体内耗是研究原子迁移、微观结构演化的重要方法,对理解固体结构缺陷动力学弛豫过程具有重要作用。本文从能量和应力应变滞回曲线出发推导了固体力学内耗表达式,后结合内耗与固体微观结构缺陷弛豫的本征关联概述了晶态固体和非晶态固体力学弛豫模式的研究前沿,这对于固体黏弹性力学的课程教学具有重要借鉴价值。本文结合作者近几年的固体内耗理论教学实践及研究成果,从教学内容、教学方法和教学环节等方面探讨该课程的教学。文中的教学措施可为其他讲授力学课程的教师提供参考。  相似文献   

5.
试样的内耗值与振动系统内耗值的比较   总被引:2,自引:1,他引:1       下载免费PDF全文
推导了四个力学模型和它们对应振动系统的内耗表达式,并给出了试样内耗值与振动系统内耗值的关系.发现对于不同的力学模型,或者说不同力学性质的材料,试样的内耗值与振动系统的内耗值有不同的关系. 关键词:  相似文献   

6.
前言     
龚昌德  闵乃本  朱劲松 《物理学进展》2006,26(3):I0009-I0009
金秋十月,值此第八届全国内耗与力学谱会议(10月19-22日)在南京召开之际,迎来了王业宁教授的八十寿辰.  相似文献   

7.
前言     
金秋十月,值此第八届全国内耗与力学谱会议(10月19-22日)在南京召开之际,迎来了王业宁教授的八十寿辰.……  相似文献   

8.
多孔NiTi形状记忆合金阻尼性能的测量和应用   总被引:1,自引:0,他引:1  
本文利用苏州职业大学测试技术研究所设计改进的LMR-1型低频力学驰豫谱测量系统(低频扭摆式内耗仪)强迫振动方式,在0℃~200℃温度范围内测量了不同成分和孔隙率NiTi合金的内耗和模量性质,为设计多孔NiTi合金在耗能减振方面的应用提供依据.  相似文献   

9.
本文利用苏州职业大学测试技术研究所设计改进的LMR-1型低频力学驰豫谱测量系统(低频扭摆式内耗仪)强迫振动方式,在0℃~200℃温度范围内测量了不同成分和孔隙率NiTi合金的内耗和模量性质,为设计多孔NiTi合金在耗能减振方面的应用提供依据.  相似文献   

10.
我们用最近研制成功的LMA型低频力学谱测试系统对NiTi合金马氏体相进行了在很大频率范围内(0.003~1Hz)的低频等温力学谱和温度谱的测量.我们研究的形状记忆合金NiTi(Ni50.2at%)试样长34mm,直径1mm细丝.经一定热处理,分别在333K.343K和353K做了内耗随频率的变化的测量。实验表明:频率越小,内耗越大,也就是内耗随频率减少而增大。同时我们采用阶梯升温的方法在八个温度下每个温度测量三种频率(1Hz,0.1Hz,0.01Hz)的内耗,结果清楚地表明:不同频率下,内耗峰都出现在372K(99℃)。而且频率越低,峰高越高。这是具有相变峰的特点:相变峰的峰温不随测量频率不同而变化,相变峰高度随频率减少而增大。我们还测量了在1Hz与0.5Hz频率下内耗随温度的变化。本文用马氏体相的位错理论初步讨论了上述实验结果。  相似文献   

11.
The longitudinal ultrasonic attenuation measurements have been made using pulse echo method at fundamental frequencies of 2, 4, 6 and 8 MHz in 20WO3–(80−x) TeO2xPbO ternary tellurite glasses (x=10, 12.5, 15, 17.5 and 20 mol%) in the temperature range 160–280 K. The results showed the presence of a broad peak which shifts to higher temperature with increasing frequency. The ultrasonic attenuation peaks suggest that the experimental behavior is controlled by thermally activated structural relaxations. The internal friction, acoustic activation energy, deformation potential, relaxation strength, number of loss centers and density of state have been calculated both as a function of temperature and PbO content. The acoustic activation energy was found to decrease from 0.156 to 0.135 eV with the increase of PbO content. The results showed that both the number of loss centers and their activation energy decrease with the atomic ring size. An increase in the density of state is observed with addition of PbO content at the same frequency in the whole range of temperature which is associated with structural units formed when PbO is added.  相似文献   

12.
在千周和兆周两个频段分别测量了含Cd为46.1at%,47.5at%,50.0at%和52.5at%的AuCd合金中与马氏体转变有关的内耗和杨氏模量。实验结果表明,在千周范围,由于马氏体转变引起的Q-1(内耗)是静滞后型的。Q-1峰的形成可以用弹性软化及界面位错的静滞后阻尼机制来解释。而兆周范围的超声衰减是与频率有关的,表明尚有共振型及弛豫型阻尼的成份。此外,实验还观察到AuCd合金的等温马氏体转变Q-1峰以及预马氏体相变Q-1峰。 关键词:  相似文献   

13.
烧结过程中Ni-Al金属间化合物形成的内耗   总被引:1,自引:0,他引:1       下载免费PDF全文
Ni-Al金属间化合物是一类重要的高温结构材料,在多种领域具有明确的目标需求.粉末冶金技术是制备Ni-Al金属间化合物的一种重要选择.探索烧结过程中Ni-Al金属间化合物形成和转变过程,明确固相扩散反应发生温度和金属间化合物种类对调控烧结工艺和优化产品质量至关重要.本文采用内耗技术系统研究了Ni-Al粉末混合物压坯烧结过程的内耗行为.在内耗-温度谱上观察到一个显著内耗峰,随测量频率的增大而降低,但峰温无明显频率依赖性.同时,内耗峰随升温速率的增大向高温方向移动且峰值增加.分析认为,该峰与升温过程中金属间化合物NiAl3和Ni2Al3的形成有关,属于典型的相变内耗峰.此外,机械球磨可调控Ni-Al粉末混合物的微观结构,内耗峰随球磨时间增加向低温方向移动且峰值降低,表明固相扩散反应可在低温区域以较低速率进行.这与球磨过程中粉末颗粒的细化、粉末混合物的片层化、固溶度和表面能的提高以及缩短的原子扩散路径有关.同时也表明机械球磨可有效降低固相扩散反应起始温度进而降低烧结温度.  相似文献   

14.
Internal friction measurements were performed on various ?111? tilt and twist grain boundaries in high-purity Al bicrystals. The temperature dependence of the grain boundary internal friction peak was determined, and the activation parameters of grain boundary relaxation were obtained. These parameters were found to change in a wide range depending on boundary geometry. The activation enthalpy of boundary relaxation and the pre-exponential factor of the relaxation time are related according to the compensation effect. The results are discussed in terms of the model of correlated relaxations. Bicrystals with vicinal Σ3 boundaries were observed to behave like single crystals, i.e. an internal friction peak did not appear. This evidences that both coherent and incoherent (60° ?111? tilt) twins possess a high mechanical resistance.  相似文献   

15.
The amplitude, temperature, and time dependences of the Young’s modulus and internal friction (ultrasonic attenuation) of a eucalyptus-based carbon biomatrix intended for preparing biomorphic silicon carbide ceramics were studied. Adsorption and desorption of molecules of the ambient medium (air) was shown to determine, to a considerable extent, the effective Young’s modulus and acoustic vibration decrement of a specimen. A doublet maximum in the temperature dependence of ultrasonic attenuation was observed at a temperature close to the sublimation temperature of solid CO2. The microplastic properties of the material were estimated from acoustic measurement data.  相似文献   

16.
王雅谷  王业宁 《物理学报》1985,34(4):520-527
用四个频率(f=31,50,72,93MHz)超声纵波测量了钼酸钆晶体铁弹铁电相变(Tc=160.90℃)引起的超声衰减(αs)峰。得到较准确的αs正比f2的关系,求得Tc以上αs的临界指数从1.52±0.12变到0.89±0.12。有渡越现象。用低频(f=1Hz和150kHz)测出了相变内耗峰,肯定其为相界面运动所引起。并求得界面运动的临界应力,从而确定了本文中测得的超声衰 关键词:  相似文献   

17.
The paper contains an investigation of broadband pulsed ultrasonic spectroscopy techniques, intended for testing of suspensions, such as a liquid-particle flow containing small diameter particles. Influence of traditional and novel broadband pulse shapes on quality of frequency spectra is analysed, as well as pulse design aspects leading to an optimal shape of an ultrasonic excitation wave. Effects that may influence signal quality and method reliability in a given setup, in particular resonances and noise are discussed. Solutions for signal acquisition and averaging techniques are presented, as well as results of testing of instrumentation limits and overall performance. Results of acoustic spectroscopy measurement of a concentrated liquid-particle flow are provided. A number of experimental and numerical examples, together with comprehensive explanations, show a potential for ultrasonic attenuation spectroscopy to be a successful methodology for an on-line measurement of fluid-particle suspensions and composite non-homogeneous materials in general.  相似文献   

18.
In the food industry, ultrasonic cutting is used to improve separation by a reduction of the cutting force. This reduction can be attributed to the modification of tool–workpiece interactions at the cutting edge and along the tool flanks because of the superposition of the cutting movement with ultrasonic vibration of the cutting tool. In this study, model experiments were used to analyze friction between the flanks of a cutting tool and the material to be cut. Friction force at a commercial cutting sonotrode was quantified using combined cutting–friction experiments, and sliding friction tests were carried out by adapting a standard draw-off assembly and using an ultrasonic welding sonotrode as sliding surface. The impact of material parameters, ultrasonic amplitude, and the texture of the contacting food surface on friction force was investigated. The results show that ultrasonic vibration significantly reduces the sliding friction force. While the amplitude showed no influence within the tested range, the texture of the contact surface of the food affects the intensity of ultrasonic transportation effects. These effects are a result of mechanical interactions and of changes in material properties of the contact layer, which are induced by the deformation of contact points, friction heating and absorption heating because of the dissipation of mechanical vibration energy.  相似文献   

19.
付磊  韩军  龙晋桓 《应用声学》2023,42(2):434-442
金属增材制件在航空航天、核电等高端领域应用日益广泛,及时获取缺陷和微观组织结构信息,对改进制造过程、保证产品质量和相关设备的安全稳定运行具有重要意义。然而,特殊的制造工艺导致金属增材制件内部晶粒粗大,组织各向异性复杂,声波衰减严重,给超声检测带来了很大挑战。该文简要梳理了金属增材制造过程中常见的缺陷类型和成型件微观组织结构特征;从传统水浸式超声检测、相控阵超声检测和激光超声检测3个方面,重点论述了超声检测技术在金属增材制件缺陷检测领域的应用现状;提出基于超声检测技术无损评价金属增材制件微观组织结构和力学性能的原理以及评价模型建立方法,并对相关重难点做了阐述;最后总结了超声无损检测技术在金属增材制件质量评价领域应用中面临的挑战和发展趋势,并对未来应重点关注的研究方向给出建议。  相似文献   

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