期刊文献+
共找到7篇文章
< 1 >
每页显示 20 50 100
类石墨烯二维原子晶体的微态理论模型 被引量:2
1
作者 杨刚 张斌 《力学学报》 EI CSCD 北大核心 2015年第3期451-457,共7页
基于微态(Micromorphic)连续介质理论,提出了针对类石墨烯二维原子晶体的新力学模型.该模型以有限大小的布拉维单胞为基元体,考虑基元粒子的宏观位移和微观变形,依据微态理论基本方程,推导了全局坐标系下模型的主导方程.然后针对布拉维... 基于微态(Micromorphic)连续介质理论,提出了针对类石墨烯二维原子晶体的新力学模型.该模型以有限大小的布拉维单胞为基元体,考虑基元粒子的宏观位移和微观变形,依据微态理论基本方程,推导了全局坐标系下模型的主导方程.然后针对布拉维单胞中含有两个原子的类石墨烯晶体,通过分析单胞中声子振动模式与基元体自由度的关系,获得了微态形式下声子色散关系的久期方程,并根据二维晶体声子色散特性对久期方程进行了简化,进而确定了类石墨烯晶体模型的本构方程.最后,以石墨烯和单层六方氮化硼为例,利用简化的表达式拟合了它们面内声子色散关系数据,计算了模型材料的常数,石墨烯模型的等效杨氏模量、泊松比分别为1.05 TPa和0.197,氮化硼分别为0.766TPa和0.225,均与已有的实验值相符合. 展开更多
关键词 二维原子晶体 微态理论 材料常数 声子色散关系 本构方程
下载PDF
多孔材料微态多尺度计算方法的数值实现与应用
2
作者 黄俊想 阮洪势 +3 位作者 陈娟娟 许杨剑 梁利华 鞠晓喆 《固体力学学报》 CAS CSCD 北大核心 2023年第5期637-647,共11页
对多孔材料进行有限元建模通常需要极其精细的网格,因而采用直接数值模拟方法有着非常高的建模和计算的成本.传统的一阶计算均匀化框架局限于宏观特征长度远远大于非均质性所在尺度特征长度的问题.为此,本文基于微态多尺度理论,提出多... 对多孔材料进行有限元建模通常需要极其精细的网格,因而采用直接数值模拟方法有着非常高的建模和计算的成本.传统的一阶计算均匀化框架局限于宏观特征长度远远大于非均质性所在尺度特征长度的问题.为此,本文基于微态多尺度理论,提出多孔材料的微态多尺度计算方法,并应用商业软件MATLAB实现微态多尺度计算均匀化框架.理论上,引入运动场分解,并将宏-微观能量等效通过Hill-Mandel条件自然地联系起来,进而导出宏-微观控制方程.算例结果表明,微态多尺度分析方法拥有较高的计算精度与计算效率.该方法具有良好的通用性,能够为多孔材料的设计和实际工程应用提供有力工具. 展开更多
关键词 多孔材料 微态理论 多尺度方法 代表性体积单元 周期性边界条件
原文传递
Similarity theory based method for MEMS dynamics analysis 被引量:2
3
作者 李瑰贤 彭云峰 张欣 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2008年第3期312-316,共5页
A new method for MEMS dynamics analysis is presented,ased on the similarity theory. With this method, two systems' similarities can be captured in terms of physics quantities/governed-equations amongst different e... A new method for MEMS dynamics analysis is presented,ased on the similarity theory. With this method, two systems' similarities can be captured in terms of physics quantities/governed-equations amongst different energy fields, and then the unknown dynamic characteristics of one of the systems can be analyzed according to the similar ones of the other system. The probability to establish a pair of similar systems among MEMS and other energy systems is also discussed based on the equivalent between mechanics and electrics, and then the feasibility of applying this method is proven by an example, in which the squeezed damping force in MEMS and the current of its equivalent circuit established by this method are compared. 展开更多
关键词 similarity theory MEMS dynamics equivalent between mechanics and electrics equivalent circuit
下载PDF
含约束薄膜的单轴拉伸的理论与数值研究 被引量:2
4
作者 张朝晖 高原 +2 位作者 聂君锋 胡强 庄茁 《工程力学》 EI CSCD 北大核心 2011年第11期31-37,共7页
基于微态理论与应变梯度弹性理论框架,对含约束薄膜的单轴拉伸问题进行了研究。推导出在不同微观约束边界条件下薄膜单轴拉伸的解析解,较好的预测了薄膜内的边界层效应。通过分析两种理论之间的内在联系,发现可选取微态理论中的耦合因... 基于微态理论与应变梯度弹性理论框架,对含约束薄膜的单轴拉伸问题进行了研究。推导出在不同微观约束边界条件下薄膜单轴拉伸的解析解,较好的预测了薄膜内的边界层效应。通过分析两种理论之间的内在联系,发现可选取微态理论中的耦合因子作为罚参数,使得微态理论可以退化至应变梯度弹性理论。计算结果表明施加罚参数后的有限元解在边界层区域外与应变梯度弹性解析解吻合较好,即由于耦合因子的罚参数特性,使得基于微态理论开发的有限元程序可以应用于应变梯度弹性理论的模拟解答。 展开更多
关键词 微态理论 应变梯度弹性 有限元 罚参数 边界层 单轴拉伸
原文传递
Multiconfigurational Study of the Electronic Structure of Negatively Charged Fullerens
5
作者 Fereshteh Naderi Valera Veryazov 《Journal of Chemistry and Chemical Engineering》 2017年第1期30-36,共7页
Multiconfigurational second order perturbation theory was employed in order to describe the ground and excited states of C60^-n. Different choices of the active spaces are discussed and the possibility to apply multic... Multiconfigurational second order perturbation theory was employed in order to describe the ground and excited states of C60^-n. Different choices of the active spaces are discussed and the possibility to apply multiconfigurational theory to study C12o is investigated. The calculations were performed for all possible spin states (for selected charge) and show the preference of low spin state. The energy difference between two C60^-3 and pairs C60^-1- C60^-5 and C60^-2- C60^-4 shows that the probability to create a charge alternation in fullerides is small. 展开更多
关键词 FULLERENES FULLERIDES multiconfigurational theory electronic structure.
下载PDF
Review and Discussion on Seismic Subsidence of Loess 被引量:2
6
作者 Wang Qiang Sun Junjie +1 位作者 Wang Lanmin Chen Xiuqing 《Earthquake Research in China》 2013年第4期479-489,共11页
The research and achievements made on seismic subsidence of loess,obtained over the past30 years,were reviewed.Seismic Subsidence of Loess(SSL)has been verified by microstructure characteristics,dynamic triaxial exper... The research and achievements made on seismic subsidence of loess,obtained over the past30 years,were reviewed.Seismic Subsidence of Loess(SSL)has been verified by microstructure characteristics,dynamic triaxial experiments,and in-situ explosion tests,and has become an important subject in the field of seismic loess engineering research.While,the research is still in the stage of theoretical study of saturated soil,and there are no representative cases of seismic subsidence of loess in historical earthquakes.It is difficult to express structure characteristics using microstructure morphology.While,soil mechanics are available methods for this.Seismic subsidence judgment is absolute in some certain value ranges for several parameters.Therefore,probabilistic judgment should be developed.The seismic subsidence ratio is estimated mostly by empirical formulas or semiempirical and semi-theoretical formulas,which are based on laboratory data.These formulas are not established on the basis of physical process and mechanics of seismic subsidence,and this leads to more variables,complicated computation,and poor practicability.To solve these problems,we need to distinguish the main factors and corresponding variables,to establish a mechanics model for seismic subsidence estimation,and to characterize its physio-mechanical process.The key of anti-seismic subsidence treatment is to reduce the seismic subsidence property of soils,and to lower the interaction between the soil body and underground structures. 展开更多
关键词 Seismic Subsidence of Loess (SSL) Mechanism of seismic subsidence Seismic subsidence assessment Estimation of seismic subsidence amount MICROSTRUCTURE
下载PDF
Nonrelativistic Lamb shift in a nano-sized conducting ring
7
作者 OLESEN D. S. KELLER O. 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS 2012年第8期1383-1388,共6页
A theoretical calculation of the nonrelativistic Lamb shift in nano-sized semiconducting (GaAs) and metallic (AI) circular rings is carried out. On the basis of a flat one-electron potential with infinitely high b... A theoretical calculation of the nonrelativistic Lamb shift in nano-sized semiconducting (GaAs) and metallic (AI) circular rings is carried out. On the basis of a flat one-electron potential with infinitely high barriers, the radiative back-action is obtained to second order in perturbation theory. Numerical results are presented for the radiative correction to the transition frequency between the ground state and first excited radial quantum states (initial state: (1,1,0), final state: (2,1,0)) neglecting the curvature term in the Schr6dinger equation. Lamb shifts are calculated as functions of the inner ring radius, the ring thickness, and the temperature. 展开更多
关键词 Lamb shift nano-ring mesoscopic quantum electrodynamics
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部