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Table of Content
08 April 2008, Volume 30 Issue 2
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    Education Study
    2008, 30(2):  96-97.  doi:10.6052/1000-0992-2006-339
    Abstract ( 1138 )   PDF (400KB) ( 542 )  
    A method for solving torsion of thin-walled prismatic rods with complex cross-section was presented. Based on the Prandtl's stress function solution, this method draws on the network theory approach in electrical circuit analysis via electrical analogy. The method is applicable for engineering problems of torsion of thin-walled rods with complex cross-section. It is also of pedagogic significance. Above-mentioned method will broaden students' horizon and enable them to gain more knowledge of interdisciplinary interaction.
    Application study
    2008, 30(2):  62-66.  doi:10.6052/1000-0992-2006-371
    Abstract ( 931 )  
    Based on the inversion from the response to load, an identification method of vehicle load on a bridge by using monitoring information is presented in this paper. In this method, the relation of the monitored force indices and the vehicle load on the bridge is established by constructing the influential functions of the indices on the measurement section. The actual example indicates that the method can fairly and accurately identify the weight of the vehicle across the bridge.
    2008, 30(2):  35-39.  doi:10.6052/1000-0992-2006-460
    Abstract ( 1400 )   PDF (777KB) ( 587 )  
    Measurements of liquid level are affected by liquid fluctuation in connected pipe. To address this problem, mathematical model of liquid flows based on a three-channel connected pipe is set up with the knowledge of hydromechanics. Mathematic equations of liquid fluctuation in the three-channel connected pipe are obtained and generated to the case of multi-channel connected pipe. With Matlab software, properties of liquid fluctuation in time domain are obtained for different system parameters. Experimental results show that our analysis about the multi-channel connected pipe is correct.
    2008, 30(2):  78-82.  doi:10.6052/1000-0992-2006-493
    Abstract ( 1043 )   PDF (966KB) ( 715 )  
    According to the local horizontal freeing construction of a metro tunnel, the surface subsidence in the procedure of tunnel excavation is forecasted and the fields of stress and strain in tunnel frozen soil wall is analyzed, the results and the survey of project are equally. Based on this model, The correlative factors of surface distortion induced by local horizontal freezing method construction are analyzed. Finally, the results can indicate: increasing the thickness of frozen soil wall has a little influence on surface subsidence, but through the method of expanding the area of frozen soil wall or decreasing tunnel's radius and depth can control surface subsidence effectively. The results can provides reference to similar construction methods.
    Education Study
    Application study
    2008, 30(2):  21-25.  doi:10.6052/1000-0992-2007-118
    Abstract ( 1863 )   PDF (977KB) ( 580 )  
    A numerical scheme for solving transient two-phase flows in interior ballistics is induced according to the theory of space-time conservation element and solution element (CE/SE) method under the transformed coordinates. The ignition process of two-dimensional two-phase flows is studied by the CE/SE method. Compared with the experimental data, the numerical results simulate the actual process. At the initial phase of ignition, a steep pressure gradient exists along the radial and axial directions in barrel chamber. When all the propellants are ignited, the pressure gradient in the radial direction vanishes. It shows that the two-dimensional CE/SE method is effective for solving transient two-phase flows in guns.
    2008, 30(2):  26-29.  doi:10.6052/1000-0992-2007-119
    Abstract ( 1105 )   PDF (678KB) ( 754 )  
    Electrorheological fluids are new intelligent materials. They are of great significance to study the viscoelastic properties of ER devices in an electric field. In this paper, forced ocsillation experiments of electrorheological fluids have been studied by HAAKE RS600 rheometer and the changes of ERF storage modulus, loss modulus and loss factor with shear stress and shear frequency are obtained for different shear stress rates and oscillation frequencies.
    2008, 30(2):  30-34.  doi:10.6052/1000-0992-2007-134
    Abstract ( 1087 )   PDF (1123KB) ( 628 )  
    Based on the equivalence of tension and bending stiffness, the tube bundle in the fixed tube-sheet kettle-type re-boiler with slant conical shell was considered as an equivalent cylinder. According to the equivalence of axial load and Poission' effect, the pressures acting respectively on the circular tubing area of the sheet and on tubes were converted into corresponding equivalent pressures. A simplified model was thus established for the slant conical shell stress analysis in which the tube-sheet and tube bundle was expected to be considered. Finite element analysis indicates that a considerable bending stress occurs at the knuckle region of the big side. Based on the design analysis, SIFs(Stress Intensity Factors) are worked out and SIF curves are given for the knuckle region of the big side.
    2008, 30(2):  49-52.  doi:10.6052/1000-0992-2007-149
    Abstract ( 1180 )   PDF (613KB) ( 633 )  
    This paper discusses fundamental assumption and simplification of the thin-layer element. The thin-layer element constitutive model can be obtained from the constitutive model of transversely isotropic materials. The constitutive relation of thin-layer elements in crak can be obtained by using the distributed crack model. The fundamental assumption of thin-layer elements can assure calculation accuracy and simplify calculation to a certain extent.
    2008, 30(2):  16-20.  doi:10.6052/1000-0992-2007-171
    Abstract ( 1235 )   PDF (901KB) ( 757 )  
    This article introduces the problem of robot motion plan and control strategy corresponding to the dynamic environment (for example collision avoidance with moving obstacles and attacking goals etc). The global optimal path/velocity space planning and their characteristics are analyzed. The article mainly deals with the planning problem aiming at stochastic motion obstacles or goals, constructs the corresponding solutions and gives comparisons with some traditional methods. The simulation results proved the effectiveness of the method.
    2008, 30(2):  53-57.  doi:10.6052/1000-0992-2007-212
    Abstract ( 1080 )   PDF (894KB) ( 778 )  
    Using piecewise linearity system theory, the nonlinear response of a clearance-restriction cantilever beam system to a harmonic excitation is researched. Firstly, the dynamic model of this system is built. Based on the transmission function, the dynamical equation and its solution are derived. The obtained numerical solution show the change feature of the dynamic response character with the excitation frequency, excitation amplitude, contact rigidity and contact dumper.
    2008, 30(2):  70-73.  doi:10.6052/1000-0992-2007-227
    Abstract ( 1221 )   PDF (804KB) ( 716 )  
    Based on the hypothesis of the EMR created by atom perturbation resulting from propagating cracks during rock fracture, the crack length and area are calculated through fracture mechanics under small yield condition. The expression of the EMR amplitude and rock's attribute parameters is presented according to the relation between EMR amplitude and crack length and area. The dependence of the EMR amplitude on each attribute parameter is discussed. The obtained results show that the EMR amplitude increases with the elastic modulus and the influence of rock dimension on the EMR is greater than its lithology. The results of this paper are in good agreement with many experimental measurements.
    2008, 30(2):  74-77.  doi:10.6052/1000-0992-2007-239
    Abstract ( 1217 )   PDF (652KB) ( 648 )  
    Combined the consolidated project of Gaochang Soil Ruins in Xinjiang Province, and directed toward the new type of geo-filament bolt, the theoretical analysis of bearing capacity is done based on the Mindlin theory of fully grouted bolt. The site test results are compared with the theory. In addition, the surface state and the failure mode are researched. The experimental study reveals that the geo-filament bolt can satisfy the consolidation requires of the earthen architecture site and the change of the bolt surface through adding ribs affects obviously the anchor force. The geo-filament bolt is proved to be an excellent material for the walls reinforcement of earthen architecture sites.
    2008, 30(2):  83-86.  doi:10.6052/1000-0992-2007-266
    Abstract ( 1191 )   PDF (1666KB) ( 602 )  
    The design method of medical elastic assistive devices based on reverse engineering is proposed, and the expression for calculating strain energy of the elastic device is deduced in the paper. To increase design efficiency, the techniques of mesh simplification and parameterization are used respectively for decreasing scanned data and changing three dimensional data into two dimensional one. To provide doctors and sufferers with scientific foundation for choose of medical device, the relationship between the device dimension and the strain energy is constructed by using the density function of strain energy.
    2008, 30(2):  58-61.  doi:10.6052/1000-0992-2007-296
    Abstract ( 1378 )   PDF (576KB) ( 714 )  
    An exact numerical method was explored for Timoshenko-beam harmonic response. In the space domain, element free method relative only with the node was used and governing equations are the equivalent weak form instead of differential form. The amendment variation principle was used to meet displacement boundary conditions and a least squares method to get the shape function. The shape function was taken into the equivalent of the weak points to get the second-order discrete equation. In the time domain, precise integration was used and Romberg integration was adopted for the non-homogeneous term. Finally, two examples of numerical results were obtained for the harmonic response problem at two different boundary conditions.
    2008, 30(2):  40-44.  doi:10.6052/1000-0992-2007-310
    Abstract ( 1038 )   PDF (1005KB) ( 544 )  
    In order to study the collapse mechanism of a mine tailings dam and comprehensive treatment, the following aspects are investigated: the granularity composition and strength parameters of mine tailings, the distribution of tailings deposits, the change of seepage condition of the dam body due to the rainfall and flood impounding of the tailings reservoir and drainage facilities. The stability against sliding of the dam is analyzed. According to unsaturated soil theory, the main reasons causing dam collapse include the increase in water content of soil resulting from rainfall and flood impounding and the decrease in shear strength due to the decrease of soil suction, as well as the insufficient drainage and reinforcement. Some comprehensive treatments for partial collapse of the dam are also suggested.
    2008, 30(2):  45-48.  doi:10.6052/1000-0992-2007-320
    Abstract ( 1042 )   PDF (673KB) ( 1071 )  
    Through dynamic river bed experiments and fine sand river bed in lower Yellow River, localized scouring on piers under unsteady flow when river channel is narrowed in large scale is researched. The result indicates that the localized scouring on piers under unsteady flood and scouring under steady flood are different and related necessarily. Through analysis of influencing factors and experiment data, their relation and relevant calculating methods of localized scouring depth on piers under unsteady flow are established. Compared with prototype observed data under unsteady flow flood, the result is reasonable and accords the practice well.
    2008, 30(2):  67-69.  doi:10.6052/1000-0992-2007-392
    Abstract ( 1114 )   PDF (503KB) ( 571 )  
    If there is usually no anchor measure in the end, the prestressed level provided by the usage of prestressed FRP reinforcement is limited and does not reach the desired results. While relying entirely on the permanent mechanical anchorage, the high cost of anchoring fixture is not beneficial to the widespread application of prestressed FRP reinforcement technology. Through the analysis of stress state of the end after release of prestressed FRP, it is found that the appropriate increase of the thickness of cohesive layer and the improvement of its deformation performance can increase substantially the end bonding ability to satisfy the needs of prestressed reinforcement. The additional simple anchorage measures can further improve the capacity and reliability of anchorage. This analysis provides a theoretical basis for the prestressed FRP reinforcement technology to reduce the cost and to simplify the construction process.
    Education Study
    2008, 30(2):  100-101.  doi:10.6052/1000-0992-2007-450
    Abstract ( 1046 )   PDF (437KB) ( 525 )  
    The software~development method that combined a BFB developing mode and a building block structure was proposed for fast developing the hydraulics solver, a kind of hydraulics CAI software. The advantages of this kind of developing method are that we can make full use of the existing codes, extend the software conveniently, and easily cooperate with others. The software is User-friendly and meets the needs in hydraulics teaching.
    Around the mechanics
    2008, 30(2):  108-109.  doi:10.6052/1000-0992-2007-484
    Abstract ( 1599 )   PDF (565KB) ( 870 )  
    Based on the action of a person on a swing, a rigid body system with three rigid bodies is developed to model the swing system. Then the dynamic process of the swing system is numerically simulated with the application of MSC ADAMS. The results show that the swaying amplitude of a swing is characteristically decided by the frequency and initial phase of the movement of the person on the swing. Some other important conclusions are also obtained.
    2008, 30(2):  11-15.  doi:10.6052/1000-0992-2007-492
    Abstract ( 1159 )   PDF (1247KB) ( 625 )  
    The recent advances in continuum methods for carbon nanotubes are presented. The continuum methods for carbon nanotubes as beam/shell/membrane models, multi-scale methods, molecular structural mechanics methods, nonlocal continuum methods, and meshless methods are described. This paper presents the theorem and methodology of these methods and their recent advances, and predicts the future studies in carbon nanotubes with the continuum methods.
    2008, 30(2):  1-10.  doi:10.6052/1000-0992-2007-526
    Abstract ( 1479 )   PDF (3469KB) ( 971 )  
    This paper briefly reviews the recent progress in the mechanics and geometry for biomembranes. In biomembrane mechanics, the equilibrium theory and geometrically constraint theory are introduced. In biomembrane geometry, a new gradient operator derived from biomembrane mechanics and its integral characteristics are summarized. The new gradient operator may be responsible for a new driving force on biomembrane surfaces. Besides, the mechanics and geometry for biomembranes are found to be an organic entity, behind which is a symmetric geometric system, including symmetric differential operators and symmetric integral theorems.
    2008, 30(2):  110-110.  doi:10.6052/1000-0879-2008-135
    Abstract ( 1338 )   PDF (185KB) ( 988 )