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Frequency and vibration responses of a magneto-rheological sandwich micro-beam based on modified couple stress theory and finite difference method 认领 引用
1
作者 M.JAFARI M.MOHAMMADIMEHR 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2026年第7期1581-1602,共22页
In this study,the frequency and vibration responses of a sandwich micro-beam are derived based on the modified couple stress theory(MCST).The face sheets are made of pure aluminum,and a magneto-rheological(MR)core is ... In this study,the frequency and vibration responses of a sandwich micro-beam are derived based on the modified couple stress theory(MCST).The face sheets are made of pure aluminum,and a magneto-rheological(MR)core is used to control vibrations.The displacement fields are assumed based on the classical beam theory(CBT)and modified classical beam theories.Based on Hamilton's principle,the governing equations of motion are obtained.To solve these temporal equations,the finite difference method(FDM)with an optimal number of nodes is applied.The effects of various parameters,including viscoelastic properties,magnetic fields,aspect ratio,core-to-face-sheet thickness ratio,MR materials,face sheets,and material length-scale parameters,on the frequency and vibrational response are investigated.In the literature,the effects of different parameters on the frequency response function(FRF)or vibration response are considered.The results obtained from the vibration response and FRF using the FDM show that the viscoelastic property of the MR core causes settling time in the vibration response and a decrease in the excitation frequency of the FRF.Increasing the magnetic field has a negligible effect on the excitation frequency in the FRF,but it increases the vibration response and settling time.The piezoelectric face sheets raise the FRF and suppress the vibration response of the MR sandwich micro-beam compared with the aluminum counterpart. 展开更多
关键词 frequency and vibration responses sandwich micro-beam magnetorheological(MR)core modified couple stress theory(MCST) finite difference method(FDM)
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Peridynamic Shell Model Based on Micro-Beam Bond 认领 引用 被引量：2
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作者 Guojun Zheng Zhaomin Yan +2 位作者 Yang Xia Ping Hu Guozhe Shen 《Computer Modeling in Engineering & Sciences》 SCIE EI 2023年第3期1975-1995,共21页
Peridynamics(PD)is a non-localmechanics theory that overcomes the limitations of classical continuummechanics(CCM)in predicting the initiation and propagation of cracks.However,the calculation efficiency of PDmodels i... Peridynamics(PD)is a non-localmechanics theory that overcomes the limitations of classical continuummechanics(CCM)in predicting the initiation and propagation of cracks.However,the calculation efficiency of PDmodels is generally lower than that of the traditional finite elementmethod(FEM).Structural idealization can greatly improve the calculation efficiency of PD models for complex structures.This study presents a PD shell model based on the micro-beam bond via the homogenization assumption.First,the deformations of each endpoint of themicro-beam bond are calculated through the interpolation method.Second,the micro-potential energy of the axial,torsional,and bending deformations of the bond can be established from the deformations of endpoints.Finally,the micro moduli of the shellmodel can be obtained via the equivalence principle of strain energy density(SED).In addition,a new fracture criterion based on the SED of the micro-beam bond is adopted for crack simulation.Numerical examples of crack propagation are provided,and the results demonstrate the effectiveness of the proposed PD shell model. 展开更多
关键词 Peridynamics shell micro-beam bond interpolation method crack propagation homogenization
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Instability of functionally graded micro-beams via micro-structure-dependent beam theory 认领 引用 被引量：2
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作者 Xiaobai LI Li LI Yujin HU 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2018年第7期923-952,共30页
This paper focuses on the buckling behaviors of a micro-scaled bi-directional functionally graded （FG） beam with a rectangular cross-section, which is now widely used in fabricating components of micro-nano-electro-... This paper focuses on the buckling behaviors of a micro-scaled bi-directional functionally graded （FG） beam with a rectangular cross-section, which is now widely used in fabricating components of micro-nano-electro-mechanical systems （MEMS/NEMS） with a wide range of aspect ratios. Based on the modified couple stress theory and the principle of minimum potential energy, the governing equations and boundary conditions for a micro-structure-dependent beam theory are derived. The present beam theory incorporates different kinds of higher-order shear assumptions as well as the two familiar beam theories, namely, the Euler-Bernoulli and Timoshenko beam theories. A numerical solu- tion procedure, based on a generalized differential quadrature method （GDQM）, is used to calculate the results of the bi-directional FG beams. The effects of the two exponential FG indexes, the higher-order shear deformations, the length scale parameter, the geomet- ric dimensions, and the different boundary conditions on the critical buckling loads are studied in detail, by assuming that Young＇s modulus obeys an exponential distribution function in both length and thickness directions. To reach the desired critical buckling load, the appropriate exponential FG indexes and geometric shape of micro-beams can be designed according to the proposed theory. 展开更多
关键词 bi-directional functionally graded（FG）material buckling modified couplestress theory micro-beam
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Size-dependent behaviors of viscoelastic axially functionally graded Timoshenko micro-beam considering Poisson effects 认领 引用 被引量：1
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作者 Zhou Bo Zheng Xueyao +1 位作者 Kang Zetian Xue Shifeng 《Journal of Southeast University(English Edition)》 EI CAS 2020年第2期170-180,共11页
A size-dependent continuum-based model is developed for the functionally graded(FG)Timoshenko micro-beams with viscoelastic properties,in which material parameters vary according to the power law along its axial direc... A size-dependent continuum-based model is developed for the functionally graded(FG)Timoshenko micro-beams with viscoelastic properties,in which material parameters vary according to the power law along its axial direction.The size effect is incorporated by employing the modified couple stress theory and Kelvin-Voigt viscoelastic model,so that viscous components are included in the stress and the deviatoric segments of the symmetric couple stress tensors.The components of strain,curvature,stress and couple stress are formulated by combining them with the Timoshenko beam theory.Based on the Hamilton principle,the governing differential equations and boundary conditions for the micro-beam are expressed with arbitrary beam section shape and arbitrary type of loads.The size effect,FG effect,Poisson effect,and the influence of the beam section shape on the mechanical behaviors of viscoelastic FG micro-beams are investigated by taking the simply supported micro-beam subjected to point load as an example.Results show that the size effect on deflection,normal stress and couple stress are obvious when the size of the micro-beam is small enough,and the FG effects are obvious when the size of the micro-beam is large enough.Moreover,the Poisson ratio influences the size effect significantly and the beam section shape is also an important factor influencing the mechanical behavior of the micro-beam. 展开更多
关键词 viscoelastic functionally graded micro-beam size-dependent behaviors size effect functionally graded effect Poisson effect space
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Size-dependent thermoelastic initially stressed micro-beam due to a varying temperature in the light of the modified couple stress theory 认领 引用 被引量：3
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作者 A.E.ABOUELREGAL 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2020年第12期1805-1820,共16页
The bending of the Euler-Bernoulli micro-beam has been extensively modeled based on the modified couple stress(MCS)theory.Although many models have been incorporated into the literature,there is still room for introdu... The bending of the Euler-Bernoulli micro-beam has been extensively modeled based on the modified couple stress(MCS)theory.Although many models have been incorporated into the literature,there is still room for introducing an improved model in this context.In this work,we investigate the thermoelastic vibration of a micro-beam exposed to a varying temperature due to the application of the initial stress employing the MCS theory and generalized thermoelasticity.The MCS theory is used to investigate the material length scale effects.Using the Laplace transform,the temperature,deflection,displacement,flexure moment,and stress field variables of the micro-beam are derived.The effects of the temperature pulse and couple stress on the field distributions of the micro-beam are obtained numerically and graphically introduced.The numerical results indicate that the temperature pulse and couple stress have a significant effect on all field variables. 展开更多
关键词 thermoelectricity micro-beam initial stress temperature pulse modified couple stress(MCS)theory
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Thermoelastic Damping of Functionally Graded Material Micro-Beam Resonators Based on the Modified Couple Stress Theory 认领 引用 被引量：3
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作者 Zhichao Zhang Shirong Liu 《Acta Mechanica Solida Sinica》 SCIE EI CSCD 2020年第4期496-507,共12页
Thermoelastic damping(TED)is one of the main internal energy dissipation mechanisms in microano-resonators.Accurate evaluation of TED is important in the design of micro-electromechanical systems and nano-electromecha... Thermoelastic damping(TED)is one of the main internal energy dissipation mechanisms in microano-resonators.Accurate evaluation of TED is important in the design of micro-electromechanical systems and nano-electromechanical systems.In this paper,a theoretical analysis on the TED in functionally graded material(FGM)micro-beam resonators is presented.Equations of motion and the heat conduction equation governing the thermodynamic coupling free vibration of non-homogenous micro-beams are established based on the Euler Bernoulli beam theory associated with the modified couple stress theory.Material properties of the FGM micro-beam are assumed to change in the depth direction as power-law functions.The layer-wise homogenization method is used for solving the heat conduction equation.By using the mathematical similarity of eigenvalue problem between the FGM beam and the reference homogeneous one,the complex natural frequency including TED is expressed in terms of the natural frequency of the isothermal homogenous beam.In the presented numerical results,influences of various characteristic parameters,such as beam thickness,material gradient index,structure size,vibration mode and boundary conditions,on TED are examined in detail.It shows that TED decreases with the increases in the values of length scale parameters because the latter lead to the increase in structural stiffness. 展开更多
关键词 Functionally graded material Size dependent Thermoelastic damping Micro-beam
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Effects of local thickness defects on the buckling of micro-beam 认领 引用
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作者 Andi LAI Bing ZHAO +1 位作者 Xulong PENG Chengyun LONG 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2022年第5期729-742,共14页
A buckling model of Timoshenko micro-beam with local thickness defects is established based on a modified gradient elasticity.By introducing the local thickness defects function of the micro-beam,the variable coeffici... A buckling model of Timoshenko micro-beam with local thickness defects is established based on a modified gradient elasticity.By introducing the local thickness defects function of the micro-beam,the variable coefficient differential equations of the buckling problem are obtained with the variational principle.Combining the eigensolution series of the complete micro-beam with the Galerkin method,we obtain the critical load and buckling modes of the micro-beam with defects.The results show that the depth and location of the defect are the main factors affecting the critical load,and the combined effect of boundary conditions and defects can significantly change the buckling mode of the micro-beam.The effect of defect location on buckling is related to the axial gradient of the rotation angle,and defects should be avoided at the maximum axial gradient of the rotation angle.The model and method are also applicable to the static deformation and vibration of the micro-beam. 展开更多
关键词 Timoshenko micro-beam local thickness defect modified gradient elasticity buckling
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Coupled vibrations and frequency shift of compound system consisting of quartz crystal resonator in thickness-shear motions and micro-beam array immersed in liquid 认领 引用 被引量：5
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作者 Xuan XIE Lingcheng KONG +2 位作者 Yuxi WANG Jun ZHANG Yuantai HU 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2015年第2期225-232,共8页
The dynamic characteristics of a quartz crystal resonator（QCR） in thicknessshear modes（TSM） with the upper surface covered by an array of micro-beams immersed in liquid are studied. The liquid is assumed to be inv... The dynamic characteristics of a quartz crystal resonator（QCR） in thicknessshear modes（TSM） with the upper surface covered by an array of micro-beams immersed in liquid are studied. The liquid is assumed to be inviscid and incompressible for simplicity. Dynamic equations of the coupled system are established. The added mass effect of liquid on micro-beams is discussed in detail. Characteristics of frequency shift are clarified for different liquid depths. Modal analysis shows that a drag effect of liquid has resulted in the change of phase of interaction（surface shear force）, thus changing the system resonant frequency. The obtained results are useful in resonator design and applications. 展开更多
关键词 quartz crystal resonator（QCR） micro-beam modal analysis frequency shift added mass of liquid
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STABILITY ANALYSIS OF A CAPACITIVE FGM MICRO-BEAM USING MODIFIED COUPLE STRESS THEORY 认领 引用 被引量：4
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作者 Behrokh Abbasnejad Ghader Rezazadeh Rasool Shabani 《Acta Mechanica Solida Sinica》 SCIE EI CSCD 2013年第4期427-440,共14页
Based on the Modified Couple Stress Theory,a functionally graded micro-beam under electrostatic forces is studied.The FGM micro-beam is made of two materials and material properties vary continuously along the beam th... Based on the Modified Couple Stress Theory,a functionally graded micro-beam under electrostatic forces is studied.The FGM micro-beam is made of two materials and material properties vary continuously along the beam thickness according to a power-law.Dynamic and static pull-in voltages are obtained and it is shown that the static and dynamic pull-in voltages for some materials cannot be obtained using classic theories and components of couple stress must be taken into account.In addition,it is shown that the values of pull-in voltages depend on the variation through the thickness of the volume fractions of the two constituents. 展开更多
关键词 MEMS FGM micro-beam stability pull-in voltage electrostatic pressure modified couple stress theory
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Vibration and wave propagation analysis of twisted micro-beam using strain gradient theory 认领 引用 被引量：6
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作者 M.MOHAMMADIMEHR M.J.FARAHI S.ALIMIRZAEI 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2016年第10期1375-1392,共18页
In this research, vibration and wave propagation analysis of a twisted micro- beam on Pasternak foundation is investigated. The strain-displacement relations （kine-matic equations） are calculated by the displacement... In this research, vibration and wave propagation analysis of a twisted micro- beam on Pasternak foundation is investigated. The strain-displacement relations （kine-matic equations） are calculated by the displacement fields of the twisted micro-beam. The strain gradient theory （SGT） is used to implement the size dependent effect at micro-scale. Finally, using an energy method and Hamilton＇s principle, the governing equations of motion for the twisted micro-beam are derived. Natural frequencies and the wave prop- agation speed of the twisted micro-beam are calculated with an analytical method. Also, the natural frequency, the phase speed, the cut-off frequency, and the wave number of the twisted micro-beam are obtained by considering three material length scale parameters, the rate of twist angle, the thickness, the length of twisted micro-beam, and the elastic medium. The results of this work indicate that the phase speed in a twisted micro-beam increases with an increase in the rate of twist angle. Moreover, the wave number is in- versely related with the thickness of micro-beam. Meanwhile, it is directly related to the wave propagation frequency. Increasing the rate of twist angle causes the increase in the natural frequency especially with higher thickness. The effect of the twist angle rate on the group velocity is observed at a lower wave propagation frequency. 展开更多
关键词 vibration and wave propagation analysis twisted micro-beam strain gradient theory （SGT） rate of twist angle
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Transverse shear and normal deformation effects on vibration behaviors of functionally graded micro-beams 认领 引用 被引量：2
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作者 Zhu SU Lifeng WANG +1 位作者 Kaipeng SUN Jie SUN 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2020年第9期1303-1320,共18页
A quasi-three dimensional model is proposed for the vibration analysis of functionally graded(FG)micro-beams with general boundary conditions based on the modified strain gradient theory.To consider the effects of tra... A quasi-three dimensional model is proposed for the vibration analysis of functionally graded(FG)micro-beams with general boundary conditions based on the modified strain gradient theory.To consider the effects of transverse shear and nor-mal deformations,a general displacement field is achieved by relaxing the assumption of the constant transverse displacement through the thickness.The conventional beam theories including the classical beam theory,the first-order beam theory,and the higher-order beam theory are regarded as the special cases of this model.The material proper-ties changing gradually along the thickness direction are calculated by the Mori-Tanaka scheme.The energy-based formulation is derived by a variational method integrated with the penalty function method,where the Chebyshev orthogonal polynomials are used as the basis function of the displacement variables.The formulation is validated by some comparative examples,and then the parametric studies are conducted to investigate the effects of transverse shear and normal deformations on vibration behaviors. 展开更多
关键词 quasi-three dimensional theory modified strain gradient theory function-ally graded(FG)micro-beam size effect vibration general boundary condition
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Effect of strain-gradients of surface micro-beams on frequency-shift of a quartz crystal resonator under thickness-shear vibrations 认领 引用 被引量：3
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作者 Ling-Cheng Kong Yuan-Tai Hu 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2015年第5期647-652,共6页
With introduction of the first-order strain-gradient of surface micro-beams into the energy density function,we developed a two-dimensional dynamic model for a compound quartz crystal resonator（QCR） system,consistin... With introduction of the first-order strain-gradient of surface micro-beams into the energy density function,we developed a two-dimensional dynamic model for a compound quartz crystal resonator（QCR） system,consisting of a QCR and surface micro-beam arrays.The frequency shift that was induced by micro-beams with consideration of strain-gradients is discussed in detail and some useful results are obtained,which have important significance in resonator design and applications. 展开更多
关键词 Micro-beams Strain-gradient Quartz crystal resonator Frequency shift
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Influence of surface micro-beams with large deflection on the resonance frequency of a quartz crystal resonator in thickness-shear mode vibrations 认领 引用 被引量：1
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作者 Chi Luo Jiemin Xie Yuantai Hu 《Theoretical & Applied Mechanics Letters》 CAS CSCD 2017年第2期72-75,共4页
We study the dynamic behavior of a quartz crystal resonator(QCR)in thickness-shear vibrations with the upper surface covered by an array of micro-beams(MBs)under large deflection.Through taking into account the contin... We study the dynamic behavior of a quartz crystal resonator(QCR)in thickness-shear vibrations with the upper surface covered by an array of micro-beams(MBs)under large deflection.Through taking into account the continuous conditions of shear force and bending moment at the interface of MBsesonator,dependences of frequency shift of the compound QCR system versus material parameter and geometrical parameter are illustrated in detail for nonlinear and linear vibrations.It is found that the frequency shift produces a little right(left)translation for increasing elastic modulus(lengthadius ratio)of MBs.Moreover,the frequency right(left)translation distance caused by nonlinear deformation becomes more serious in the second-order mode than in the first-order one. 展开更多
关键词 Quartz crystal resonator Nonlinear deformation Micro-beams Frequency shift
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Modeling size-dependent behaviors of axially functionally graded Bernoulli-Euler micro-beam 认领 引用
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作者 Shuai WANG Zetian KANG +2 位作者 Shichen ZHOU Bo ZHOU Shifeng XUE 《Mechanical Engineering Science》 2020年第1期17-29,共13页
This work focus on the mechanical behaviors,which are related to the size effect,functionally graded(FG)effect and Poisson effect,of an axially functionally graded(AFG)micro-beam whose elastic modulus varies according... This work focus on the mechanical behaviors,which are related to the size effect,functionally graded(FG)effect and Poisson effect,of an axially functionally graded(AFG)micro-beam whose elastic modulus varies according to sinusoidal law along its axial direction.The displacement field of the AFG micro-beam is set according to the Bernoulli-Euler beam theory.Employing the modified couple stress theory(MCST),the components of strain,curvature,stress and couple stress are expressed by the second derivative of the deflection of the AFG micro-beam.A size-dependent model related to FG effect and Poisson effect,which includes the formulations of bending stiffness,deflection,normal stress and couple stress,is developed to predict the mechanical behaviors of the AFG microbeam by employing the principle of minimum potential energy.The mechanical behaviors of a simply supported AFG micro-beam are numerically investigated using the developed model for demonstrating the size effects,FG effects and Poisson effects of the AFG micro-beam.Results show that the mechanical behaviors of AFG micro-beams are distinctly size-dependent only when the ratio of micro-beam height to material length-scale parameter is small enough.The FG parameter is an important factor that determines and regulates the size-dependent behaviors of AFG micro-beams.The influences of Poisson’s ratio on the mechanical behaviors of AFG micro-beams are not negligible,and should be also considered in the design and analysis of an AFG micro-beam.This work supplies a theoretical basis and a technical reference for the design and analysis of AFG micro-beams in the related regions. 展开更多
关键词 axially functionally graded micro-beam size-dependent behaviors size effect functionally graded effect Poisson effect
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Analytic solution for size-dependent behaviors of micro-beam under forced vibration 认领 引用
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作者 Shuai WANG Zhiyong WANG +2 位作者 Feifei WANG Bo ZHOU Shifeng XUE 《Mechanical Engineering Science》 2020年第1期48-58,共11页
This paper focuses on the size-dependently mechanical behaviors of a micro-beam under forced vibration.Governing equations of a micro-beam under forced vibration are established by using the modified couple stress the... This paper focuses on the size-dependently mechanical behaviors of a micro-beam under forced vibration.Governing equations of a micro-beam under forced vibration are established by using the modified couple stress theory,Bernoulli-Euler beam theory and D’Alembert’s principle together.A simply supported micro-beam under forced vibration is solved according to the established governing equations and the method of separation of variables.The dimensionless deflection,amplitude mode and period mode are defined to investigate the size-dependently mechanical behaviors of a micro-beam under forced vibration.Results show that the performance of a micro-beams under forced vibration is distinctly size-dependent when the ratio of micro-beam height to material length-scale parameter is small enough.Both frequency ratio and loading location are the important factors that determine the sizedependent performance of a micro-beams under forced vibration. 展开更多
关键词 micro-beam forced vibration size effect,modified couple stress theory Bernoulli-Euler beam theory
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含缺陷Timoshenko微梁的自由振动分析 认领 引用
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作者 彭斌峰 赵冰 +2 位作者 陈健 彭旭龙 龙承运 《长沙理工大学学报（自然科学版）》 CAS 2026年第1期174-183,共10页
【目的】研究厚度缺陷对微梁自由振动的影响。【方法】在Timoshenko梁的刚度表达式中引入厚度缺陷分布函数,然后基于修正梯度弹性(modified gradient elasticity,MGE)理论,利用哈密顿原理得到微梁的自由振动控制方程,最后采用Newmark-... 【目的】研究厚度缺陷对微梁自由振动的影响。【方法】在Timoshenko梁的刚度表达式中引入厚度缺陷分布函数,然后基于修正梯度弹性(modified gradient elasticity,MGE)理论,利用哈密顿原理得到微梁的自由振动控制方程,最后采用Newmark-β法和六虚节点有限差分方法对方程进行求解。【结果】缺陷深度、宽度及位置对微梁自由振动的影响都主要体现在振幅和加速度幅上,而对基频的影响极小;微梁内部特征长度参数越小,微梁振幅随缺陷宽度和深度的变化而变化的幅度越大。【结论】若仅考虑Timoshenko微梁自由振动的基频,则可忽略厚度缺陷的影响;若要考虑其振幅,则不可忽略厚度缺陷的影响。 展开更多
关键词 Timoshenko微梁 缺陷 自由振动 尺寸效应 修正梯度弹性理论
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100μm厚钛合金超薄板脉冲微束等离子弧焊焊接工艺与数值模拟 认领 引用
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作者 柴鹏 何建萍 《热加工工艺》 CAS 北大核心 2026年第6期60-66,共7页
通过脉冲微束等离子弧焊(P-MPAW)对100μm厚TC4钛合金超薄板进行对接焊试验,采用显微镜观察焊接接头的成形特征与显微组织,利用有限元软件模拟焊接过程,揭示了100μm厚钛合金超薄板脉冲微束等离子弧焊焊接机理。结果表明:平均电流2 A、... 通过脉冲微束等离子弧焊(P-MPAW)对100μm厚TC4钛合金超薄板进行对接焊试验,采用显微镜观察焊接接头的成形特征与显微组织,利用有限元软件模拟焊接过程,揭示了100μm厚钛合金超薄板脉冲微束等离子弧焊焊接机理。结果表明:平均电流2 A、占空比30%和50%,当脉冲频率25 Hz时,焊缝呈现为鱼鳞焊缝,焊缝宽度与基值电流呈反比;脉冲频率分别为100、200 Hz时,焊缝呈现为光滑连续焊缝,焊缝宽度与脉冲频率呈反比。焊接接头焊缝区微观组织为网篮组织,热影响区主要为等轴α相和β相以及针状α'相马氏体。结合工艺试验可知,有限元软件模拟不同脉冲参数下的焊缝成形与工艺试验焊缝成形相似,不同基值电流和脉冲频率对焊缝宽度的影响规律一致。 展开更多
关键词 脉冲微束等离子弧焊 TC4钛合金 有限元软件模拟 网篮组织
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基于碳纳米管纤维冷阴极的微束斑电子源 认领 引用
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作者 高健康 梁俊钟 +3 位作者 邓聪颖 张宇 佘峻聪 邓少芝 《真空电子技术》 2026年第4期25-31,共7页
微束斑电子源是实现高空间分辨率精细电子束的核心部件,在微纳真空电子器件、电子束成像、曝光和精密制造设备中具有关键应用价值。文章采用碳纳米管纤维冷阴极,利用聚焦离子束技术对碳纳米管纤维顶端形貌进行锐化微纳加工,获得端面直径... 微束斑电子源是实现高空间分辨率精细电子束的核心部件,在微纳真空电子器件、电子束成像、曝光和精密制造设备中具有关键应用价值。文章采用碳纳米管纤维冷阴极,利用聚焦离子束技术对碳纳米管纤维顶端形貌进行锐化微纳加工,获得端面直径7.5 m m的柱形尖端结构,在直流场发射工作模式下,器件最大场发射电流为1305.4 m A、电流密度为2954.8 A·cm-2、场增强因子达7169.9。设计并研制出基于碳纳米管纤维冷阴极和双膜孔静电聚焦透镜的微束斑电子源,测试结果表明,在阳极电压11 kV、阳极电流0.7 m A条件下,电子束斑尺寸为8.7 m m,达到亚10 m m尺度。该研究表明碳纳米管纤维冷阴极具有优异的电子发射性能,可用于制备微束斑电子源,在真空电子器件与设备应用中具有广阔前景。 展开更多
关键词 碳纳米管纤维 冷阴极 微束斑 电子源
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基于离子束刻蚀的未镀膜熔融石英微半球谐振结构频率裂解修调技术研究 认领 引用
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作者 李家程 卢坤 +4 位作者 席翔 石岩 孙江坤 吴学忠 肖定邦 《机械工程学报》 EI CAS CSCD 北大核心 2026年第5期319-328,共10页
熔融石英微半球谐振陀螺具有品质因数高、抗冲击性能好、体积尺寸小等显著优点,是目前精度最高的微机电陀螺之一。低损伤高精度的机械修调是微半球谐振陀螺性能提升的关键技术之一。由于微半球谐振结构初始频差大,机械修调会产生大量粉... 熔融石英微半球谐振陀螺具有品质因数高、抗冲击性能好、体积尺寸小等显著优点,是目前精度最高的微机电陀螺之一。低损伤高精度的机械修调是微半球谐振陀螺性能提升的关键技术之一。由于微半球谐振结构初始频差大,机械修调会产生大量粉尘,需要在镀膜前进行初步修调便于后续清洗。针对壳面质量刚度异常敏感和特定区域能实现质量刚度解耦的特点,提出了一种基于离子束刻蚀的未镀膜微半球谐振结构频率裂解修调技术,实现低损伤机械修调。通过理论和仿真分析了壳面修调模型对谐振结构频率裂解的影响规律,确定了修调中心区域的位置和修调尺寸的大小。针对未镀膜微半球谐振结构频率裂解的检测,建立了平面叉指电极测试系统,准确辨识出谐振结构频率裂解大小及刚性轴方向。最后,设计了离子束修调实验,对所提出的方案进行实验验证,将未镀膜微半球谐振结构频率裂解降低至100 mHz以下,有效提升了微半球谐振陀螺性能。 展开更多
关键词 微半球谐振结构 机械修调 有限元仿真 离子束修调
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飞秒涡旋光束作用金属微纳二聚体的二次谐波增强模拟(特邀) 认领 引用
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作者 李兆博 王怡欢 +2 位作者 Waqas Ahmad 杜广庆 陈烽 《红外与激光工程》 EI CAS CSCD 北大核心 2026年第4期206-215,共10页
为克服传统非线性晶体因厚度依赖而产生的集成瓶颈,满足片上光子器件对高效、微型化二次谐波光源的需求,提出一种基于飞秒涡旋光脉冲激发金属微纳二聚体的二次谐波产生与调控方法。建立了飞秒涡旋光脉冲激发金属微纳二聚体(球体及椭球体... 为克服传统非线性晶体因厚度依赖而产生的集成瓶颈,满足片上光子器件对高效、微型化二次谐波光源的需求,提出一种基于飞秒涡旋光脉冲激发金属微纳二聚体的二次谐波产生与调控方法。建立了飞秒涡旋光脉冲激发金属微纳二聚体(球体及椭球体)二次谐波增强的瞬态电磁场模型,通过有限元方法(FEM)对模型进行了数值求解。模拟结果表明:通过优化金属微纳二聚体的半径与间距,最高可以达到200倍二次谐波信号增强。相较于传统的球形结构,椭球结构通过长轴与排列角度的调整,提供了更灵活的共振匹配条件,可达到600倍的二次谐波信号增强。与高斯光束相比,飞秒涡旋光束能够在二聚体结构周围,诱导出一种独特的、具有高阶对称性的“花瓣状”近场分布。该研究揭示了微纳结构设计与光场形态之间的内在联系,验证了涡旋光在光场调控方面的潜力,为设计高性能的非线性纳米光子器件提供了重要的理论依据。提出飞秒涡旋光束激发金属微纳二聚体的二次谐波产生与调控方法,为实现片上集成化非线性光源提供了新途径。 展开更多
关键词 飞秒涡旋光 二次谐波 金属微纳二聚体 表面等离子体极化激元 局域场增强
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