共查询到20条相似文献,搜索用时 421 毫秒
1.
设计了实验装置,探究了橡皮筋弹力与伸长量的关系以及橡皮筋材料疲劳的影响因素.通过拉伸实验,发现橡皮筋的弹力和伸长量并非成严格的线性关系.定量研究了橡皮筋在相同拉伸幅度下疲劳程度与拉伸次数的关系,以及在相同拉伸次数下疲劳程度与橡皮筋拉伸幅度的关系. 相似文献
2.
利用热力学知识解释了橡皮筋受热收缩的原因.使用电子秤测量橡皮筋所受的熵力,并用温度拟合的结果得出橡皮筋定长时熵力与温度的关系,研究了橡皮筋伸长时内能的变化和熵的变化对张力的贡献.实验结果表明:常温下橡皮筋的弹力主要由构像熵引起.利用橡皮筋热缩性质制作了橡皮筋热机,当光照角度为-30°时热机平均转动速率最大,热机转动最为顺畅. 相似文献
3.
4.
5.
人教版普通高中课程标准实验教科书《物理.必修2》在"探究功与速度变化的关系"的实验中,采用的是橡皮筋的弹力做功使小车获得动能,以探究橡皮筋弹力做功与小车速度的关系,如图1.该实验精妙之处就在于回避了功的计算.橡皮筋的弹力做功是变力做功,不能用功的公式W=Fscosα计算.但在位移相同的情况下,如果一条橡皮 相似文献
6.
7.
8.
9.
10.
液体蒸发时温度降低实验的改进张兴万(云南省会泽县一中654200)1.实验装置如下图.其主要部分是带标尺的木制支架、玻管和烧瓶(标尺54Clll,玻管内直径2—m,烧瓶300ml).两玻管用乳胶管连接,固定在支架上.烧瓶用橡皮筋紧固在支架的圆弧槽上,... 相似文献
11.
The effect of elastic anisotropy on the strain fields and confinement potentials in InAs/GaAs quantum dot (QD) nanostructures was investigated for an isolated dot and a stacked multi-layer dots using finite element analysis and model solid theory. The assumption of isotropy tends to underestimate especially hydrostatic strain that is known to modify confinement potentials in conduction band. Consideration of anisotropy results in a wider band gap and shallower potential well as compared with the isotropic model. Since the band gap and potential well depth would be related to opto-electronic properties of quantum dot systems via quantum mechanical effects, it is suggested that consideration of elastic anisotropy in the calculation of strains and band structures is necessary for the design of QD-based opto-electronic devices. 相似文献
12.
Based on the transfer matrix method (TMM) and Bloch theory, the interaction of elastic waves (normal incidence) with 1D phononic crystal had been studied. The transfer matrix method was obtained for both longitudinal and transverse waves by applying the continuity conditions between the consecutive unit cells. Dispersion relations are calculated and plotted for both binary and ternary structures. Also we have investigated the corresponding effects on the band gaps values for the two types of phononic crystals. Furthermore, it can be observed that the complete band gaps are located in the common frequency stop-band regions. Numerical simulations are performed to investigate the effect of different thickness ratios inside each unit cell on the band gap values, as well as unit cells thickness on the central band gap frequency. These phononic band gap materials can be used as a filter for elastic waves at different frequencies values. 相似文献
13.
The influences of thickness of spacing layer and the elastic anisotropy on the strain fields and band edges of InAs/GaAs conical shaped quantum dots
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Based on the continuum elastic theory, this paper presents a finite
element analysis to investigate the influences of elastic anisotropy
and thickness of spacing layer on the strain field distribution and
band edges (both conduction band and valence band) of the InAs/GaAs
conical shaped quantum dots. To illustrate these effects, we give
detailed comparisons with the circumstances of isolated and stacking
quantum dot for both anisotropic and isotropic elastic
characteristics. The results show that, in realistic materials
design and theoretical predication performances of the
optoelectronic devices, both the elastic anisotropy and thickness of
the spacing layer of stacked quantum dot should be taken into
consideration. 相似文献
14.
An analysis is given to the band structure of the two-dimensional phononic crystal plate constituted of a square array of elastic anisotropic, circular Pb cylinders embedded in elastic isotropic epoxy. The numerical results show that the band gap can be tuned by rotating the anisotropic material orientation. It is found that the influence of anisotropy on band gap of Lamb wave is clearly different from that on the band gap of bulk waves. The thickness of the system under study is a sensitive parameter to affect the influence of anisotropic materials on the normalized gap width. 相似文献
15.
提出了不同结构的一维弹性波复合材料系统模型,包括一维周期结构声子晶体、标准Fibonacci准周期结构声子晶体、广义Fibonacci准周期结构声子晶体以及完全无序结构的复合材料系统. 采用模式匹配理论法,数值计算了弹性波通过一维复合材料系统的透射系数. 计算结果表明,利用特殊的准周期结构声子晶体可获得比周期结构声子晶体更宽的带隙范围,准周期结构排列的复合材料系统相当于在周期结构中引入了缺陷体一样,带隙内出现了丰富的局域模式. 对弹性波/声波在复合材料系统中局域态性质的研究有助于弹性波/声波滤波器、导波器
关键词:
弹性波复合材料
局域化 相似文献
16.
The systematic investigations of the mechanical, elastic, and electronic properties, and stability of the newly synthesized monoclinic C2/m-Ca_2C_3 are performed, based on the first-principles calculations. Ca_2C_3 is found to be mechanically and dynamically stable only from 0 GPa to 24 GPa. The elastic anisotropy studies show that Ca_2C_3 exhibits the elastic anisotropy increasing with the augment of pressure. Furthermore, using the HSE06 hybrid functional, the electronic properties of Ca_2C_3 under pressure are calculated. The structure can be regarded as a quasi-direct band gap semiconductor, and the pressure-induced direct-indirect band gap transition is studied in detail. 相似文献
17.
18.
Akimov AV Tanaka Y Pevtsov AB Kaplan SF Golubev VG Tamura S Yakovlev DR Bayer M 《Physical review letters》2008,101(3):033902
The elastic coupling between the a-SiO2 spheres composing opal films brings forth three-dimensional periodic structures which besides a photonic stop band are predicted to also exhibit complete phononic band gaps. The influence of elastic crystal vibrations on the photonic band structure has been studied by injection of coherent hypersonic wave packets generated in a metal transducer by subpicosecond laser pulses. These studies show that light with energies close to the photonic band gap can be efficiently modulated by hypersonic waves. 相似文献
19.
为了在弹性波波导中实现缺陷态的调控,该文基于相位失配原理设计了一种周期性平板波导结构。以正弦边界弹性波导为例,通过连接具有不同相位的两段波导结构,形成了弹性板中不同程度的缺陷,并分析了其谱带特性和能量局域化特征。结果表明,禁带中存在两个不同模式的缺陷态,其以透射峰形式出现并随着相位的改变产生频移。与此同时,两个缺陷态在空间上对应的应力场和位移场分布也具有不同的模态特征。该文提出的复合弹性波导缺陷态调控方法,不仅为研究弹性波与结构之间的内在联系提供了关键的理论支持,也为实际弹性波探测器件的设计提供重要参考。 相似文献
20.
Xin-Chao Yang 《中国物理 B》2022,31(2):26104-026104
Silicon is a preferred material in solar cells, and most of silicon allotropes have an indirect band gap. Therefore, it is important to find new direct band gap silicon. In the present work, a new direct band gap silicon allotrope of o-Si32 is discovered. The elastic constants, elastic anisotropy, phonon spectra, and electronic structure of o-Si32 are obtained using first-principles calculations. The results show that o-Si32 is mechanically and dynamically stable and is a direct semiconductor material with a band gap of 1.261 eV. 相似文献