共查询到19条相似文献,搜索用时 203 毫秒
1.
实现黏附可控是解决微/纳机械产品黏附失效问题和发展先进黏附材料及新型微操作/微装配技术等的有效途径. 基于该研究背景,针对干燥不带电系统,对近年来发展的几类黏附调控方法进行了综述,从表面改形、材料改性及外场控制三方面介绍了织构、涂层/薄膜和复合材料、速度、温度、外力和磁场在黏附调控方面的研究进展,分析和总结了各类方法的黏附调控机理、关键影响因素和特点,并指出了应用领域,介绍了多手段复合调控黏附方法的最新研究成果. 最后,探讨了当前黏附调控方面存在的问题和未来可能的发展方向. 相似文献
2.
3.
4.
刘曰武 高大鹏 李奇 万义钊 段文杰 曾霞光 李明耀 苏业旺 范永波 李世海 鲁晓兵 周东 陈伟民 傅一钦 姜春晖 侯绍继 潘利生 魏小林 胡志明 端祥刚 高树生 沈瑞 常进 李晓雁 柳占立 魏宇杰 郑哲敏 《力学进展》2019,49(1):201901
页岩气的开采涉及破裂和收集输运两个关键过程.如何实现2000,m以下、复杂地应力作用下、多相复杂介质组分的页岩层内网状裂纹的形成,同时将孔洞、缝隙中的游离、吸附气体进行高效收集,涉及到诸多的核心力学问题.这一工程过程涵盖了力学前沿研究的诸多领域:介质和裂纹从纳米尺度到千米尺度的空间跨越,游离、吸附气体输运过程中微秒以下的时间尺度事件到历经数年开采的时间尺度跨越,不同尺度上流体固体的相互作用,以及压裂过程中通过监测信息反演内部破坏状态等.针对近年来我们国家页岩气勘探开发工作所取得的成就及后续发展中面临的前沿力学问题,在综合介绍页岩气藏的基本特征和开发技术的基础上,以页岩气开采中的若干力学前沿问题为主线,从页岩力学性质及其表征方法、页岩气藏实验模拟技术、页岩气微观流动机制及流固耦合特征、水力压裂过程数值模拟方法、水力压裂过程微地震监测技术、高效环保的无水压裂技术等6个方面的最新研究进展进行了总结和展望,结合页岩气藏开发的工程实践, 深入探究了其中力学关键问题,以期对从事页岩气领域的开发和研究的从业人员提供理论基础, 同时,该方面的内容对力学学科、尤其是岩土力学领域的科研工作也具有重要指导价值. 相似文献
5.
Yuewu LIU Dapeng GAO Qi LI Yizhao WAN Wenjie DUAN Xiaguang ZENG Mingyao LI Yewang SU Yongbo FAN Shihai LI Xiaobing LU Dong ZHOU Weimin CHEN Yiqin FU Chunhui JIANG Shaoji HOU Lisheng PAN Xiaolin WEI Zhiming HU Xianggang DUAN Shusheng GAO Rui SHEN Jin CHANG Xiaoyan LI Zhanli LIU Yujie WEI Zhemin ZHENG 《力学进展》1971,49(1):201901
页岩气的开采涉及破裂和收集输运两个关键过程.如何实现2000,m以下、复杂地应力作用下、多相复杂介质组分的页岩层内网状裂纹的形成,同时将孔洞、缝隙中的游离、吸附气体进行高效收集,涉及到诸多的核心力学问题.这一工程过程涵盖了力学前沿研究的诸多领域:介质和裂纹从纳米尺度到千米尺度的空间跨越,游离、吸附气体输运过程中微秒以下的时间尺度事件到历经数年开采的时间尺度跨越,不同尺度上流体固体的相互作用,以及压裂过程中通过监测信息反演内部破坏状态等.针对近年来我们国家页岩气勘探开发工作所取得的成就及后续发展中面临的前沿力学问题,在综合介绍页岩气藏的基本特征和开发技术的基础上,以页岩气开采中的若干力学前沿问题为主线,从页岩力学性质及其表征方法、页岩气藏实验模拟技术、页岩气微观流动机制及流固耦合特征、水力压裂过程数值模拟方法、水力压裂过程微地震监测技术、高效环保的无水压裂技术等6个方面的最新研究进展进行了总结和展望,结合页岩气藏开发的工程实践, 深入探究了其中力学关键问题,以期对从事页岩气领域的开发和研究的从业人员提供理论基础, 同时,该方面的内容对力学学科、尤其是岩土力学领域的科研工作也具有重要指导价值. 相似文献
6.
形状记忆合金(Shape Memory Alloys, SMAs)因其具有形状记忆效应和超弹性,在航空航天、生物医疗、微机电系统领域中得到了广泛的应用.当微结构尺度达到微纳米,表面效应对微结构力学性能的影响是十分显著的.本文基于梁弯曲变形理论以及Gurtin-Murdoch表面弹性理论,考虑拉压不对称、温度对于SMA纳米梁的影响,建立了考虑表面效应的SMA纳米梁相变力学模型.分析了弯曲载荷、温度、表面残余应力以及表面弹性模量对SMA纳米梁力学性能的影响规律.研究表明在SMA纳米梁相变阶段,忽略和考虑表面效应所得的截面应力及应变相对误差较为明显;在相同弯矩下,随温度的增加SMA纳米梁的截面应力随之增加,并且表面效应对其影响有减小趋势;表面残余应力对SMA纳米梁的影响显著.该文研究结果为SMA纳米梁在微机电领域的设计以及应用提供了一定基础与依据. 相似文献
7.
8.
黏度对流固界面滑移影响的试验研究 总被引:3,自引:1,他引:2
为了研究微纳米间隙下固液界面间流体的流动及输运特性,本文改进了商用的原子力显微镜,并利用其对微纳米间隙下固液界面的边界滑移现象进行了试验研究,重点考察了流体黏度对边界滑移的影响.固体壁面样品采用Si(100)表面,试验液体采用不同黏度的去离子水和蔗糖溶液.结果表明,Si(100)表面与去离子水和蔗糖溶液作用会发生边界滑移,而且随着溶液黏度的升高,滑移长度也随之升高,表现了边界滑移与流体黏度的相关性.所得结果对于微流体输运与控制有重要的理论意义与实际价值. 相似文献
9.
Au纳米颗粒织构化表面的黏着和摩擦学行为研究 总被引:3,自引:1,他引:2
利用自组装技术在单晶硅(100)面制备了Au纳米颗粒织构化表面(nanoparticle-textured surfaces,NPTS),采用原子力显微镜(AFM)和UMT-2MT摩擦磨损试验机考察了Au纳米颗粒织构化对表面微/纳尺度黏着与摩擦性能的影响机理.结果表明:在颗粒堆积密度较低的表面,接触力学符合连续接触力学模式;在颗粒堆积密度较高的表面,形成多峰接触,有效地减少了接触面积,降低了黏着和摩擦.与光滑硅表面相比,组装时间为3.0 h的Au纳米颗粒织构化表面的黏着力降低了77%,在试验载荷为7 nN时,其摩擦力降低了42%. 相似文献
10.
11.
Transfer printing is an important and versatile tool for deterministic assembly and integration of micro/nanomaterials on unusual substrates, with promising applications in fabrication of stretchable and flexible electronics. The shape memory polymers (SMP) with triangular surface relief structures are introduced to achieve large, reversible adhesion, thereby with potential applications in temperature-controlled transfer printing. An analytic model is established, and it identifies two mechanisms to increase the adhesion: (1) transition of contact mode from the triangular to trapezoidal configurations, and (2) explicit enhancement in the contact area. The surface relief structures are optimized to achieve reversible adhesion and transfer printing. The theoretical model and results presented can be exploited as design guidelines for future applications of SMP in reversible adhesion and stretchable electronics. 相似文献
12.
Elastocapillary phenomena involving elastic deformation of solid structures coupled with capillary effects of liquid droplets/films can be observed in a diversity of fields,e.g.,biology and microelectromechanical systems(MEMS).Understanding the physical mechanisms underlying these phenomena is of great interest for the design of new materials and devices by utilizing the effects of surface tension at micro and nano scales.In this paper,some recent developments in the investigations on elastocapillary phenomena are briefly reviewed.Especially,we consider the deformation,adhesion,self-assembly,buckling and wrinkling of materials and devices induced by surface tensions or capillary forces.The main attention is paid to the experimental results of these phenomena and the theoretical analysis methods based on continuum mechanics.Additionally,the applications of these studies in the fields of MEMS,micro/nanometrology,and biomimetic design of advanced materials and devices are discussed. 相似文献
13.
Recent experiments and molecule dynamics simulations have shown that adhesion droplets on conical surfaces may move spontaneously
and directionally. Besides, this spontaneous and directional motion is independent of the hydrophilicity and hydrophobicity
of the conical surfaces. Aimed at this important phenomenon, a general theoretical explanation is provided from the viewpoint
of the geometrization of micro/nano mechanics on curved surfaces. In the extrinsic mechanics on micro/nano soft curved surfaces,
we disclose that the curvatures and their extrinsic gradients form the driving forces on the curved spaces. This paper focuses
on the intrinsic mechanics on micro/nano hard curved surfaces and the experiment on the spontaneous and directional motion.
Based on the pair potentials of particles, the interactions between an isolated particle and a micro/nano hard curved surface
are studied, and the geometric foundation for the interactions between the particle and the hard curved surface is analyzed.
The following results are derived: (a) Whatever the exponents in the pair potentials may be, the potential of the particle/hard
curved surface is always of the unified curvature form, i.e., the potential is always a unified function of the mean curvature
and the Gaussian curvature of the curved surface. (b) On the basis of the curvature-based potential, the geometrization of
the micro/nano mechanics on hard curved surfaces may be realized. (c) Similar to the extrinsic mechanics on micro/nano soft
curved surfaces, in the intrinsic mechanics on micro/nano hard curved surfaces, the curvatures and their intrinsic gradients
form the driving forces on the curved spaces. In other words, either on soft curved surfaces or hard curved surfaces and either
in the extrinsic mechanics or the intrinsic mechanics, the curvatures and their gradients are all essential factors for the
driving forces on the curved spaces. (d) The direction of the driving force induced by the hard curved surface is independent
of the hydrophilicity and hydrophobicity of the curved surface, explaining the experimental phenomenon of the spontaneous
and directional motion. 相似文献
14.
微/纳尺度接触问题计算方法研究进展 总被引:7,自引:0,他引:7
接触问题广泛存在于现实生活的众多领域,近来随着微/纳米技术的不断发展,接触力学在基础理论和研究方法上面临许多新的挑战.本文在摩擦学的范畴内,对近年发展的若干求解微/纳尺度接触问题的计算方法及理论进行了综述.按发展先后及所解决问题的尺度范围划分,主要有3类评估微/纳尺度接触性能的计算方法:(1)连续介质力学方法;(2)分子动力学模拟; (3)多尺度方法.介绍了这3类计算方法的典型理论和主要数学描述,给出了这些方法对解决若干微/纳观接触问题如黏着效应、粗糙表面描述、表面摩擦及润滑、表面热效应、生物接触等的主要应用.最后, 探讨了微/纳尺度接触问题计算方法可能的发展方向及应用领域. 相似文献
15.
This paper describes a dynamical strategy for releasing micro objects picked-up by means of adhesion forces. While sticking effects are used in order to capture an object by adequately choosing a high surface energy constitutive material for the end-effector, these same effects handicap considerably the release. We propose to take advantage of the inertial effects of both the end-effector and the manipulated object to overbalance adhesion forces and to achieve the release. Simulations show that for this purpose, accelerations as high as 105 m/s2 are needed. Successful manipulation of a 40 μm radius glass sphere is demonstrated. To cite this article: S. Haliyo et al., C. R. Mecanique 331 (2003). 相似文献
16.
The governing differential equation of micro/nanbeams with atom/molecule adsorption is derived in the presence of surface effects using the nonlocal elasticity.The effects of the nonlocal parameter,the adsorption density,and the surface parameter on the resonant frequency of the micro/nanobeams are investigated.It is found that,in addition to the nonlocal parameter and the surface parameter,the bending rigidity and the adsorption-induced mass exhibit different behaviors with the increase in the adsorption density depending on the adatom category and the substrate material. 相似文献
17.
The vibration method represents a practical method for the measurement of adhesion forces and adhesion force distributions. This method causes sinusoidally altemating stresses and yields detachment and contact forces between particles and substrate of the same order of magnitude. Alternating contact forces of the vibration method can cause an adhesion force intensification through flattening of asperities. The measuring principle of the vibration method and the analysis of experimental results are described in the article. Normal adhesion forces (pull-off forces) are measured using the vibration method and the colloidal probe technique. The results of both methods show good agreement for small particle sizes. The influence of the detachment force direction is shown by comparing tangential and normal adhesion forces measured using particle reentrainment in a turbulent air flow and the vibration method, respectively. The surface roughness of the substrate and the relative humidity are shown to significantly influence the measured adhesion forces. For the calculation of the adhesion forces, an approach by Rabinovich was combined with approximations of plastic micro asperity flattening. The Rabinovich approach accounts for roughness effects on the van der Waals force by incorporating the rms roughness of the interacting surfaces. rms-values of the particles and substrates were measured with atomic force microscopy at different scanning areas. 相似文献
18.
A nonlocal elastic micro/nanobeam is theoretically modeled with the consideration of the surface elasticity, the residual surface stress, and the rotatory inertia, in which the nonlocal and surface effects are considered. Three types of boundary conditions, i.e., hinged-hinged, clamped-clamped, and clamped-hinged ends, are examined. For a hinged-hinged beam, an exact and explicit natural frequency equation is derived based on the established mathematical model. The Fredholm integral equation is adopted to deduce the approximate fundamental frequency equations for the clamped-clamped and clamped-hinged beams. In sum, the explicit frequency equations for the micro/nanobeam under three types of boundary conditions are proposed to reveal the dependence of the natural frequency on the effects of the nonlocal elasticity, the surface elasticity, the residual surface stress, and the rotatory inertia, providing a more convenient means in comparison with numerical computations. 相似文献
19.
微/纳器件表面微观粗糙结构间由于液体介质而引起的弯月面力和黏着力是导致器件精度降低乃至失效的主要原因之一。通过建立微/纳米尺度上球面-平面接触的物理模型,基于Young-Laplace方程和Reynolds润滑理论,分析得到粗糙表面接触分离过程中弯月面力和黏着力的计算公式。在此基础上,计算得到接触表面分离过程中的弯月面形状变化规律,并分别讨论了固体表面分离距离、液滴初始弯月面高度、固体表面润湿性能和分离时间等因素对弯月面力和黏着力的影响。研究结果为微/纳米表面抗黏着机理提供了理论依据。 相似文献