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| 1 | A semi-spring and semi-edge combined contact model in CDEM and its application to analysis of Jiweishan landslide显示文摘Continuum-based discrete element method(CDEM)is an explicit numerical method used for simulation of progressive failure of geological body.To improve the efficiency of contact detection and simplify the calculation steps for contact forces,semi-spring and semi-edge are introduced in calculation.Semispring is derived from block vertex,and formed by indenting the block vertex into each face(24semisprings for a hexahedral element).The formation process of semi-edge is the same as that of semi-spring(24semi-edges for a hexahedral element).Based on the semi-springs and semi-edges,a new type of combined contact model is presented.According to this model,six contact types could be reduced to two,i.e.the semi-spring target face contact and semi-edge target edge contact.By the combined model,the contact force could be calculated directly(the information of contact type is not necessary),and the failure judgment could be executed in a straightforward way(each semi-spring and semi-edge own their characteristic areas).The algorithm has been successfully programmed in C++program.Some simple numerical cases are presented to show the validity and accuracy of this model.Finally,the failure mode,sliding distance and critical friction angle of Jiweishan landslide are studied with the combined model. | Chun Feng Shihai Li Xiaoyu Liu Yanan Zhang | 2014 | Journal of Rock Mechanics and Geotechnical Engineering2014，6，1： | 34 |
| 2 | Third-order point contact approach for five-axis sculptured surface machining using non-ball-end tools (Ⅰ): Third-order approximation of tool envelope surface显示文摘In this paper, the geometric properties of a pair of line contact surfaces are investigated. Then, based on the observation that the cutter envelope surface contacts with the cutter surface and design surface along the characteristic curve and cutter contact (CC) path, respectively, a mathematical model describing the third-order approximation of the cutter envelope surface according to just one given cutter location (CL) is developed. It is shown that at the CC point both the normal curvature of the normal section of the cutter envelope surface and its derivative with respect to the arc length of the normal section can be determined by those of the cutter surface and design surface. This model characterizes the intrinsic relationship among the cutter surface, cutter envelope surface and design surface in the neighborhood of the CC point, and yields the mathematical foundation for optimally approximating the cutter envelope surface to the design surface by adjusting the cutter location. | ZHU LiMin1, DING Han2 & XIONG YouLun2 1 State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai 200240, China 2 State Key Laboratory of Digital Manufacturing Equipment and Technology, Huazhong University of Science and Technology, Wuhan 430074, China | 2010 | Science China(Technological Sciences)2010，53，7： | 25 |
| 3 | Third-order point contact approach for five-axis sculptured surface machining using non-ball-end tools(II): Tool positioning strategy显示文摘Based on the mathematical model describing the third-order approximation of the cutter envelope surface according to one given cutter location(CL),a tool positioning strategy is proposed for efficiently machining free-form surfaces with non-ball-end cutters.The optimal CL is obtained by adjusting the inclination and tilt angles of the cutter until its envelope surface and the design surface have the third-order contact at the cutter contact(CC)point,which results in a wide machining strip.The strategy can handle the constraints of machine joint angle limits,global collision avoidance and tool path smoothness in a nature way,and can be applied to general rotary cutters and complex surfaces.Numerical examples demonstrate that the third-order point contact approach can improve the machining strip width greatly as compared with the recently reported second-order one. | ZHU LiMin 1 ,DING Han 2 &XIONG YouLun 2 1State Key Laboratory of Mechanical System and Vibration,Shanghai Jiao Tong University,Shanghai 200240,China 2State Key Laboratory of Digital Manufacturing Equipment and Technology,Huazhong University of Science and Technology,Wuhan 430074, China | 2010 | Science China(Technological Sciences)2010，53，8： | 23 |
| 4 | Investigation of changes in properties of water under the action of a magnetic field显示文摘The properties of water and their changes under the action of a magnetic field were gathered by the spectrum techniques of infrared, Raman, visible, ultraviolet and X-ray lights, which may give an insight into molecular and atomic structures of water. It was found that some properties of water were changed, and a lot of new and strange phenomena were discovered after magnetization. Magnetized water really has magnetism, which has been verified by a peak shift of X-ray diffraction of magnetized water + Fe3O4 hybrid relative to that of pure water + Fe3O4 hybrid, that is a saturation and memory effect. The properties of infrared and ultraviolet absorp-tions, Raman scattering and X-ray diffraction of magnetized water were greatly changed relative to those of pure water; their strengths of peaks were all increased, the frequencies of some peaks did also shift, and some new peaks, for example, at 5198, 8050 and 9340 cm?1, occurred at 25℃ after water was magnetized. In the meanwhile, the magnetized effects of water are related to the magnetized time, the intensity of an externally applied magnetic field, and the temperature of water, but they are not a linear relationship. The study also showed a lot of new and unusual properties of magnetized water, for example, the six peaks in 3000-3800 cm?1 in infrared absorption, the exponential increase of ultraviolet absorption of wave with the decreasing wavelength of light of 200-300 nm, the frequency-shifts of peaks, a strange irreversible effect in the increasing and decreasing processes, as well as a stronger peak of absorption occurring at 50℃, 70℃ and 80℃, the existence of many models of motion from 85℃ to 95℃ in 8000-10000 cm?1, and so on. These results show that the molecular structure of water is very complicated, which needs further study. Furthermore, the macroscopic feature of mechanics, for instance, surface tension force of magnetized water, was also measured. Experiments dis-covered that the size in contact angles of magnetized water on the surface of hy-drophobic materials decreases, thus the surface tension force of magnetized water decreases relative to that of pure water. It is seen from the above results that the clustering structure of hydrogen-bonded chains and polarization effects of water molecules are enhanced after magnetization. These results are helpful in revealing the mechanism of magnetization of water. | PANG XiaoFeng1,2 & DENG Bo1 1 Institute of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054, China 2 International Centre for Materials Physics, Chinese Academy of Sciences, Shenyang 110015, China | 2008 | Science China(Physics,Mechanics & Astronomy)2008，51，11： | 23 |
| 5 | Gear geometry of cycloid drives显示文摘According to differential geometry and gear geometry, the equation of meshing for small teeth difference planetary gearing and a universal equation of conjugated profile are established based on cylindrical pin tooth and given motion. The correct meshing condition, contact line, contact ratio, calculating method for pin tooth's maximum contact point are developed. Investigation on the theory of conjugated meshing is carried out when the tooth difference numbers between pin wheel and cycloidal gear are 1, 2, 3 and ?1, respectively. A general method called enveloping method to generate hypocycloid and epicycloid is put forward. The correct meshing condition for cycloid pin wheel gearing is provided, and the contact line and the contact ratio are also discussed. | CHEN BingKui FANG TingTing LI ChaoYang WANG ShuYan | 2008 | Science China(Technological Sciences)2008，51，5： | 18 |
| 6 | Modification Design Method for an Enveloping Hourglass Worm Gear with Consideration of Machining and Misalignment Errors显示文摘The influences of machining and misalignment errors play a very critical role in the performance of the anti-backlash double-roller enveloping hourglass worm gear(ADEHWG).However,a corresponding efficient method for eliminating or reducing these errors on the tooth profile of the ADEHWG is seldom reported.The gear engagement equation and tooth profile equation for considering six different errors that could arise from the machining and gear misalignment are derived from the theories of differential geometry and gear meshing.Also,the tooth contact analysis(TCA) is used to systematically investigate the influence of the machining and misalignment errors on the contact curves and the tooth profile by means of numerical analysis and three-dimensional solid modeling.The research results show that vertical angular misalignment of the worm wheel(Δβ) has the strongest influences while the tooth angle error(Δα) has the weakest influences on the contact curves and the tooth profile.A novel efficient approach is proposed and used to minimize the effect of the errors in manufacturing by changing the radius of the grinding wheel and the approaching point of contact.The results from the TCA and the experiment demonstrate that this tooth profile design modification method can indeed reduce the machining and misalignment errors.This modification design method is helpful in understanding the manufacturing technology of the ADEHWG. | DENG Xingqiao WANG Jinge HORSTEMEYER Mark F | 2013 | Chinese Journal of Mechanical Engineering2013，26，5： | 16 |
| 7 | Discontinuous deformation analysis based on complementary theory显示文摘The contact between blocks is treated by the open-close iteration in the conventional discontinuous deformation analysis (DDA),which needs to introduce spurious springs between two blocks in contact and to assume the normal stiffness and the tangential stiffness (the penalty factors). Unreasonable values of stiffness would result in numerical problems. To avoid the penalty factors and the open-close iteration,we reformulate the DDA as a mixed complementary problem (MiCP) and then choose the path Newton method (PNM) to solve the problem. Some examples including those originally designed by Shi are reanalyzed,which proves feasibility of the proposed procedure. | ZHENG Hong1,2 & JIANG Wei2 1 China Three Gorges University,Key Laboratory of Geological Hazards on Three Gorges Reservoir Area,Ministry of Education, Yichang 443002,China 2 State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan 430071,China | 2009 | Science China(Technological Sciences)2009，52，9： | 15 |
| 8 | AXISYMMETRIC CONTACT PROBLEM OF CUBIC QUASICRYSTALLINE MATERIALS显示文摘The axisymmetric elasticity theory of cubic quasierystal was developed in Ref.[1].The axi-symmetric elasticity problem of cubic quasicrystal is reduced to a single higher-order partial differentialequation by introducing a displacement function,based on which,the exact analytic solutions for the elasticfield of an axisymmetric contact problem of cubic quasicrystalline materials are obtained for universal contactstress or contact displacement.The result shows that if the contact stress has order-1/2 singularity on theedge of the contact domain,the contact displacement is a constant in the contact domain.Conversely,if thecontact displacement is a constant,the contact stress must have order-1/2 singularity on the edge of thecontact domain. | Zhou Wangmin Fan Tianyou Yin Shuyuan | 2002 | Acta Mechanica Solida Sinica2002，15，1： | 14 |
| 9 | 基于半赫兹接触的车轮磨耗计算显示文摘为了分析轮轨接触模型对车轮磨耗计算的影响,基于半赫兹接触、赫兹接触和Kalker完全理论程序CONTACT分别计算轮轨接触应力和接触斑形状,并在Kalker简化理论基础上求解半赫兹接触的蠕滑力;基于Archard磨耗模型,计算车轮磨耗深度在踏面上的分布.计算结果表明:由于半赫兹接触考虑了接触斑内曲率的变化,则接触斑形状和最大接触应力比赫兹接触更接近于CONTACT计算结果;在大自旋蠕滑工况下,应用半赫兹接触得到的横向蠕滑力与CONTACT计算结果有较大偏差,其余工况相差不超过18%;基于半赫兹接触的FASTSIM计算时间约为基于赫兹接触的6倍,是CONTACT计算时间的1/166;半赫兹接触时,考虑弹性滑动速度的车轮磨耗深度更接近于CONTACT计算结果. | 丁军君 李芾 黄运华 | 2011 | 西南交通大学学报2011，46，2： | 14 |
| 10 | Dynamics of vehicle-pavement coupled system based on a revised flexible roller contact tire model显示文摘A revised flexible roller contact tire model (RFRC tire model) is proposed, which considers not only the geometric and flexible filtering effect, but also tire damping and pavement displacement. A vehi- cle-pavement coupled system is modeled as a two DOF oscillator moving along a simply supported beam on a linear viscoelastic foundation. By using the Galerkin’s and Direct Integral method, dynamical responses of the vehicle-pavement coupled system are obtained based on the RFRC tire model and the traditional single point contact tire model (SPC tire model). The simulation results are compared with test data and the validity of the proposed RFRC tire model is verified. Differences between the two models are also investigated. It is found that the dynamical behaviors for both models agree with each other quite well when road surface roughness is a long harmonic wave. On the other hand, they are different under short harmonic wave or impulse road excitation. Thus the RFRC tire model should be used to compute the tire force and investigate dynamical responses of vehicle and pavement. | YANG ShaoPu LI ShaoHua LU YongJie | 2009 | Science China(Technological Sciences)2009，52，3： | 13 |
| 11 | 刺激性接触性皮炎的研究进展显示文摘 | 周承藩 沈彤 朱启星 | 2005 | 中华劳动卫生职业病杂志2005，23，6： | 13 |
| 12 | Clinical correlates of common corneal neovascular diseases: a literature review显示文摘A large subset of corneal pathologies involves the formation of new vessels(neovascularization), leading to compromised visual acuity. This article aims to review the clinical causes and presentations of corneal neovascularization(CNV) by examining the mechanisms behind common CNV-related corneal pathologies, with a particular focus on herpes simplex stromal keratitis,contact lenses-induced keratitis and CNV secondary to keratoplasty. Moreover, we reviewed CNV in the context of different types of corneal transplantation and keratoprosthesis, and summarized the most relevant treatment available so far. | Nizar Saleh Abdelfattah Mohamed Amgad Amira A Zayed Hamdy Salem Ahmed E Elkhanany Heba Hussein Nawal Abd El-Baky | 2015 | International Journal of Ophthalmology(English edition)2015，8，1： | 10 |
| 13 | Hydrogen Gas Sensor Based on Nanocrystalline SnO_2 Thin Film Grown on Bare Si Substrates显示文摘In this paper, high-quality nanocrystalline SnO_2 thin film was grown on bare Si(100) substrates by a sol–gel method. A metal–semiconductor–metal gas sensor was fabricated using nanocrystalline SnO_2 thin film and palladium(Pd)metal. The contact between Pd and nanocrystalline SnO_2 film is tunable. Ohmic barrier contact was formed without addition of glycerin, while Schottky contact formed by adding glycerin. Two kinds of sensor devices with Schottky contact were fabricated(Device 1: 8 h, 500 °C; Device 2: 10 h, 400 °C). The room temperature sensitivity for hydrogen(H_2) was120 and 95 % in 1000 ppm H_2, and the low power consumption was 65 and 86 l W for two devices, respectively. At higher temperature of 125 °C, the sensitivity was increased to 195 and 160 %, respectively. The sensing measurements were repeatable at various temperatures(room temperature, 75, 125 °C) for over 50 min. It was found that Device 1 has better sensitivity than Device 2 due to its better crystallinity. These findings indicate that the sensors fabricated on bare Si by adding glycerin to the sol solution have strong ability to detect H_2 gas under different concentrations and temperatures. | Imad H.Kadhim H.Abu Hassan Q.N.Abdullah | 2016 | Nano-Micro Letters2016，8，1： | 9 |
| 14 | Modeling Superhydrophobic Contact Angles and Wetting Transition显示文摘It is well known that surface roughness has a very important effect on superhydrophobicity.The Wenzel and Cassie-Baxtermodels,which correspond to the homogeneous and heterogeneous wetting respectively,are currently primary instructions fordesigning superhydrophobic surfaces.However,the particular drop shape that a drop exhibits might depend on how it is formed.A water drop can occupy multiple equilibrium states,which relate to different local minimal energy.In some cases,both equilibriumstates can even co-exist on a same substrate.Thus the apparent contact angles may vary and have different values.Wediscuss how the Wenzel and Cassie-Baxter equations determine the homogeneous and heterogeneous wetting theoretically.Contact angle analysis on hierarchical surface structure and contact angle hysteresis has been put specific attention.In particular,we study the energy barrier of transition from Cassie-Baxter state to Wenzel state,based on existing achievement by previousresearchers,to determine the possibility of the transition and how it can be interpreted.It has been demonstrated that surfaceroughness and geometry will influence the energy required for a drop to get into equilibrium,no matter it is homogeneous orheterogeneous wetting. | Nan Gao, Yuying YanDBE, Faculty of Engineering, University of Nottingham, NGl 2RD, UK | 2009 | Journal of Bionic Engineering2009，6，4： | 9 |
| 15 | 三种眼压计在准分子激光原位角膜磨镶术后的应用比较显示文摘目的评价三种不同眼压计在近视准分子激光原位角膜磨镶术后的应用。方法对近视33例66眼和LASIK术后43例86眼分别用非接触眼压计(non-contacttonometerNCT),Goldmann压平眼压计(Goldmannapplanationtonometer,GAT)和Tono-Pen压平眼压计测量眼压(Tono-Pen眼压计测量角膜中央和颞下距角膜缘1.5~2mm处的眼压),同时测角膜中央及颞下方的厚度。结果用三种方法测得的近视眼LASIK术后的眼压测量值均明显低于正常近视眼。两组均为Tono-Pen和NCT与GAT测量值呈正相关,LASIK术后中央Tono-Pen眼压测量值与术前GAT呈正相关。眼压与角膜厚度的关系:近视眼组,NCT与角膜中央厚度呈正相关;GAT和Tono-Pen与角膜厚度无相关性。LASIK术后组,GAT和NCT与角膜厚度呈正相关;Tono-Pen与角膜中央厚度无相关性。结论LASIK术后眼压测量值下降。Tono-Pen测量IOP不受角膜厚度的影响,可应用于LASIK术后等角膜表面不平者。 | 晏晓明 李海丽 王捷 | 2005 | 中国实用眼科杂志2005，23，6： | 9 |
| 16 | Review of prediction for thermal contact resistance显示文摘Theoretical prediction research on thermal contact resistance is reviewed in this paper. In general, modeling or simulating the thermal contact resistance involves several aspects, including the descriptions of surface topography, the analysis of micro mechanical deformation, and the thermal models. Some key problems are proposed for accurately predicting the thermal resistance of two solid contact surfaces. We provide a perspective on further promising research, which would be beneficial to understanding mechanisms and engineering applications of the thermal contact resistance in heat transport phenomena. | WANG AnLiang1 & ZHAO JianFeng2 1 School of Astronautics, Beihang University, Beijing 100191, China China Academy of Space Technology, Beijing 100094, China | 2010 | Science China(Technological Sciences)2010，53，7： | 9 |
| 17 | Wetting Behaviours of a Single Droplet on Biomimetic Micro Structured Surfaces显示文摘Natural surfaces with super hydrophobic properties often have micro or hierarchical structures.In this paper, the wettingbehaviours of a single droplet on biomimetic micro structured surfaces with different roughness parameters are investigated.Atheoretical model is proposed to study wetting transitions.The results of theoretical analysis are compared with those of experimentindicating that the proposed model can effectively predict the wetting transition.Furthermore, a numerical simulationbased on the meso scale Lattice Boltzmann Method (LBM) is performed to study dynamic contact angles, contact lines, andlocal velocity fields for the case that a droplet displays on the micro structured surface.A spherical water droplet with rs= 15 μmfalls down to a biomimetic square-post patterned surface under the force of gravity with an initial velocity of 0.01 m·s-1 and aninitial vertical distance of 20 μm from droplet centre to the top of pots.In spite of a higher initial velocity, the droplet can stillstay in a Cassie state; moreover, it reaches an equilibrium state at t≈17.5 ms, when contact angle is 153.16° which is slightlylower than the prediction of Cassie-Baxter’s equation which gives θCB=154.40°. | Y.Q.Zu~1,Y.Y.Yan~1,J.Q.Li~2,Z.W.Han~2 1.Faculty of Engineering,University of Nottingham,Nottingham NG7 2RD,UK 2.Key Laboratory of Bionic Engineering (Ministry of Education,China),Jilin University,Changchun 130022,P.R.China | 2010 | Journal of Bionic Engineering2010，7，2： | 8 |
| 18 | The apparent contact angle of water droplet on the micro-structured hydrophobic surface显示文摘The apparent contact angle of Cassie-Baxter state water droplets can be calculated by the existing theoretical formula, but due to the defects of the micro-structured hydrophobic surface and some inevitable tiny disturbances in the experiment, Cassie-Baxter state water droplets will appear partly in Wenzel state, that is, the mixed state water droplets. In this paper, apparent contact angles of Cassie-Baxter state and mixed state water droplets on micro-structured hydrophobic surfaces are compared. The research shows that if the projected area fraction of water-solid F in the Cassie-Baxter formula is replaced by the local projected area fraction of water-solid F′, the apparent contact angles of water droplets in both Cassie-Baxter state and the mixed state can be calculated. Further experimental results indicate that the contact state of water droplets nearby the outermost three-phase contact line plays a more important role in determining the apparent contact angle. This conclusion is significant to the understanding of the apparent contact angle and wetting property. | YANG ChangWei, HE Feng & HAO PengFei School of Aerospace, Tsinghua University, Beijing 100084, China | 2010 | Science China Chemistry2010，53，4： | 8 |
| 19 | Computational dynamics of soft machines显示文摘Soft machine refers to a kind of mechanical system made of soft materials to complete sophisticated missions, such as handling a fragile object and crawling along a narrow tunnel corner, under low cost control and actuation.Hence, soft machines have raised great challenges to computational dynamics. In this review article, recent studies of the authors on the dynamic modeling, numerical simulation, and experimental validation of soft machines are summarized in the framework of multibody system dynamics. The dynamic modeling approaches are presented first for the geometric nonlinearities of coupled overall motions and large deformations of a soft component, the physical nonlinearities of a soft component made of hyperelastic or elastoplastic materials, and the frictional contacts/impacts of soft components,respectively. Then the computation approach is outlined for the dynamic simulation of soft machines governed by a set of differential-algebraic equations of very high dimensions,with an emphasis on the efficient computations of the nonlinear elastic force vector of finite elements. The validations of the proposed approaches are given via three case studies, including the locomotion of a soft quadrupedal robot,the spinning deployment of a solar sail of a spacecraft, and the deployment of a mesh reflector of a satellite antenna,as well as the corresponding experimental studies. Finally,some remarks are made for future studies. | Haiyan Hu Qiang Tian Cheng Liu | 2017 | Acta Mechanica Sinica2017，33，3： | 7 |
| 20 | Two kinds of contact problems in three-dimensional icosahedral quasicrystals显示文摘Two kinds of contact problems, i.e., the frictional contact problem and the adhesive contact problem, in three-dimensional(3D) icosahedral quasicrystals are discussed by a complex variable function method. For the frictional contact problem, the contact stress exhibits power singularities at the edge of the contact zone. For the adhesive contact problem, the contact stress exhibits oscillatory singularities at the edge of the contact zone. The numerical examples show that for the two kinds of contact problems,the contact stress exhibits singularities, and reaches the maximum value at the edge of the contact zone. The phonon-phason coupling constant has a significant effect on the contact stress intensity, while has little impact on the contact stress distribution regulation. The results are consistent with those of the classical elastic materials when the phonon-phason coupling constant is 0. For the adhesive contact problem, the indentation force has positive correlation with the contact displacement, but the phonon-phason coupling constant impact is barely perceptible. The validity of the conclusions is verified. | Xuefen ZHAO Xing LI Shenghu DING | 2015 | Applied Mathematics and Mechanics(English Edition)2015，36，12： | 7 |
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