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08 June 2009, Volume 31 Issue 3
Education Study
2009, 31(3):  78-79.  doi:10.6052/1000-0992-2007-157
Abstract ( 1837 )   PDF (322KB) ( 502 )
The value and direction of static friction are various with the external force. Based on the Euler’s friction law, the internal force in a flexible belt surrounded in a fixed cylinder is exponential distribution when it is in critical status, or just before macroscopic slipping. In this paper, the internal force distribution and relation between force and deformation of the belt was studied when the external force loaded and unloaded. The results show that internal force can be increase or decrease in exponent at any point of the belt, which is determined by the loading history; although the belt is linear elastic material, the relation between external force and the total deformation is nonlinear. The relation in unloading process is different to the loading, and a hysteretic loop is produced in the curve of force and deformation. And every point inside the loop is a capable state of the force and deformation of the belt.
2009, 31(3):  76-77.  doi:10.6052/1000-0992-2007-539
Abstract ( 1403 )   PDF (440KB) ( 509 )
A circular column,s completely rolling in a free circular concave trough on a smooth horizontal plane is investigated.the track equation of the circular column,s mass center and any point on the circular column,s edge in inertial frame of reference is deduced, the strict isochronism vibration condition is given,and the tracks is sketched by a computer; the period of vibration when the circular column is completely rolling is calculated,and the period of vibration when the circular column is completely rolling to when the circular column is completely glide are compared.
Application study
2009, 31(3):  16-22.  doi:10.6052/1000-0879-2008-043
Abstract ( 1273 )   PDF (1496KB) ( 766 )
The inflatable deployment tube is a basic support component of space inflatable structures, and a Z-folded configuration is one of the basic folding ways of the inflatable deployment tube of the inflatable solar array discussed in this paper. A model of segments inflatable control volume for deployment process of inflatable tubes is proposed. The inflatable deployment of the Z-folded tube is simulated by finite element method under zero gravity condition. The variations of the volume and pressure in each folded segment are analyzed. Influence of inflation rate on deployment dynamic characteristics is discussed, and compared with those in literature. An inflatable deployment experiment on an air track is conducted. The results demonstrate that variations of inflation rate have a great influence on the deployment process, and increasing the reduction factor of the inflation rate can decrease the impact force action of the tube at the full deployment.
Education Study
2009, 31(3):  73-74.  doi:10.6052/1000-0879-2008-088
Abstract ( 922 )   PDF (260KB) ( 571 )
Application study
2009, 31(3):  35-38.  doi:10.6052/1000-0879-2008-115
Abstract ( 1215 )   PDF (725KB) ( 519 )
Based on the assumptions of the output displacement of the giant magnetostrictive material, a nonlinear dynamic model for the giant magnetostrictive transducer is built, in which the output mandril is used as the main parameter and the nonlinear hysteresis inside the giant magnetostrictive material and the prestressed spring characteristics are considered at the same time. The Simulink system is used in the dynamic simulation process of the giant magnetostrictive transducer system. The dynamic simulation results indicate that the transducer system is in a stable period movement with non-linear hysteresis characteristics. The numerical results obtained in this paper agree well with the experiment results in literature. The results also show that the square term in the relation for the nonlinear spring is the main factor that influences the transducer system model.
2009, 31(3):  61-63.  doi:10.6052/1000-0879-2008-128
Abstract ( 1056 )   PDF (763KB) ( 722 )
A high-piled wharf in use for more five years are studied with model experiment to obtain the uneven settlement of large-diameter concrete pipes. First, physical parameters for the model (PVC piles) are chosen through dimensional analysis, and then, the uneven settlement of the large-diameter concrete pipe is obtained by electrical measurement technology. At the same time, a numerical simulation is carried out to validate the model experiment results. It is shown that it is feasible to analyze the uneven settlement of the large-diameter concrete pipe with a numerical simulation.
2009, 31(3):  69-72.  doi:10.6052/1000-0879-2008-164
Abstract ( 1091 )   PDF (668KB) ( 632 )
The finite element motion equation of plate is deduced, the stiffness and mass matrixes with consideration of the moment of inertia are constructed and the first several natural frequencies are calculated by using the sub-space iteration method. The vibration property of generalized conforming thick/thin element ATF-PQ4a is studied. The influence of moment of inertia and shearing distortion on the natural frequencies are discussed. The results obtained by using this element agree well with those obtained by ABAQUS and the theoretical solution. It can be concluded that the element ATF-PQ4a can be used for both thick and thin plates in the dynamics range for engineering purposes.
Education Study
2009, 31(3):  87-89.  doi:10.6052/1000-0879-2008-201
Abstract ( 863 )   PDF (466KB) ( 524 )
According to the obtained data of the irregularly retrograde satellite groups of Jupiter, we assumed that the parent of the satellite group had conic orbit relative to Jupiter before it broke up, and estimated the dynamics parameters of the irregularly retrograde satellite group parent of Jupiter.
Application study
2009, 31(3):  16-22.  doi:10.6052/1000-0879-2008-226
Abstract ( 959 )   PDF (1037KB) ( 538 )
为了研究爆炸及燃烧产生的蘑菇''状烟云，采用中尺度气象模式RAMS(regional atmospheric modeling system)模拟研究了冲击波过后的爆炸烟云运动过程. 流场和涡 度场结果显示，对于稳定层结大气条件，爆炸烟云在浮力作用下会形成浮力涡环结构； 烟云在到达最大高度以后，形成了环套环的多涡结构. 通过模拟不同爆炸当量和不同大 气稳定度的烟云上升最大高度，得到了与目前常用的爆炸烟云上升公式一致的形式.
2009, 31(3):  44-47.  doi:10.6052/1000-0879-2008-251
Abstract ( 1277 )   PDF (831KB) ( 577 )
Cylindrical shells are commonly used components in engineering. The buckling of cylindrical shells under impact load is an important research topic. This paper studies the energy loss in the non-axisymmetric buckling of a cylindrical shell in three aspects: axial buckling, circumferential buckling and axial-compressive deformation. The results indicate that the circumferential deformation energy tends to decrease with the increase of the number of edges, and takes only a small proportion of the total deformation energy. It is concluded that during the process of the axial buckling, most of work done by the external force is converted into the axial deformation energy, only a small part is converted into the circumferential deformation energy.
2009, 31(3):  52-56.  doi:10.6052/1000-0879-2008-273
Abstract ( 1095 )   PDF (876KB) ( 578 )
The eccentric wearing of a sucker rod in polymer flooding is much more serious than that in water flooding, mainly due to the normal force of production liquid in polymer flooding. Based on the non-Newtonian fluid mechanics theory, a normal force computational model is established using the upper-convected Maxwell model, and the distribution of the normal force inside the well is confirmed and then put into the mechanical model of the sucker rod. With the real boundary condition, the analysis of the sucker rod is carried out using the finite element method. With Well FU081801 as an example simulation method is validated. The simulation result agree with the detection result, which demonstrates the applicability of this method. Through the method, we can predict the eccentric wearing position of the rods and tubes, as well as the influence of polymer concentration on the eccentric wearing of the sucker rod.
2009, 31(3):  23-26.  doi:10.6052/1000-0879-2008-282
Abstract ( 1050 )   PDF (670KB) ( 705 )
2009, 31(3):  39-43.  doi:10.6052/1000-0879-2008-296
Abstract ( 1258 )   PDF (887KB) ( 559 )
stress-strain behavior of 2D weave ceramic matrix composite is studied by experimental and theoretical methods. The 2D weave structure is simplified as a crossply structure and a fiber bundle undulation structure. Based on the matrix strength stochastic distribution theory and the fiber failure stochastic distribution theory, the stress-strain behavior and the tangent tensile modulus are obtained for unidirectional composite (0$^\circ$ ply). With the relationship between crossply and unidirectional ceramic matrix composite with the same material, the stress-strain behavior of crossply ceramic matrix composite can be obtained. A two-dimensional analytical method is proposed for fiber bundle undulation structure. With the composite strength model, the undulation structure is divided into sub-elements. The failure analysis is carried out considering the failure of different sub-elements in the fiber bundle undulation structure. Moreover, the stress-strain behavior of the undulation structure is obtained. Combining the crossply and the undulation structure's stress-strain behavior, the stress-strain behavior of of the 2D weave ceramic matrix composite is obtained; and the result agrees well with the experimental result.
2009, 31(3):  57-60.  doi:10.6052/1000-0879-2008-336
Abstract ( 1241 )   PDF (659KB) ( 561 )
To overcome the short coming in the studies on dynamic properties in which the pile is considered as a one-dimensional pole, this paper studies the dynamic properties of a pile in an axis-symmetry model. A comparison between the two models shows that the ratio of length to radius of the pile influences the eigenfrequencies of the pile. The pile can be analyzed in one dimensional model when eigenfrequencies of high order are neglected, or for the first four eigenfrequencies, the pile ratio of length to radius should be large than 3. Soil-pile stiffness has more influence on the first and second eigenfrequencies of the pile. A method is proposed to calculate soil-pile stiffness by an inverse method with the first and second eigenfrequencies of the pile, so the pile capacity can be computed.
2009, 31(3):  27-30.  doi:10.6052/1000-0879-2008-366
Abstract ( 1227 )   PDF (817KB) ( 635 )
Based on the Reynolds-Averaged Navier-Stokes equations and $k$-$\omega$ SST turbulent models, the steady and unsteady flows are computed. Coupled with the motion equations for an elastic supported airfoil, the aeroelastic dynamic responses of the symmetric airfoil with different thicknesses at different incidences are simulated in the time domain. The flow-field characteristics and the aeroelastic characteristics of airfoil with different thicknesses at high-incidence are investigated. It is shown that, the critical flutter speed does not vary monotonously with the incidence increasing from zero to high levels for various Reynolds numbers and structure parameters considered in this paper. The incidence at which the critical flutter speed begins to drop rapidly is much smaller than the incidence corresponding to the maximum lift coefficient.
Around the mechanics
2009, 31(3):  109-114.  doi:10.6052/1000-0879-2008-378
Abstract ( 1192 )   PDF (2463KB) ( 719 )
Application study
2009, 31(3):  48-51.  doi:10.6052/1000-0879-2008-405
Abstract ( 1073 )   PDF (578KB) ( 493 )
The bending of a moderately thick plate is analyzed by the meshless method with the radial point interpolation and polynomial basis functions in this paper. The global Galerkin weak-form equation for isotropic moderately thick plate is established based on Mindlin plate theory and the minimum total potential energy principle. The shape functions constructed using the radial point interpolation method with polynomial basis functions enjoy Kronecker Delta function property, so the essential boundary conditions can be easily imposed. Numerical examples show that the presented method features high efficiency, good accuracy and easy implementation. The shear locking can thus be avoided in the bending analysis for thin plates.
2009, 31(3):  64-68.  doi:10.6052/1000-0879-2008-417
Abstract ( 1177 )   PDF (841KB) ( 545 )
In our study on the steady response of asphalt pavement subjected to moving load, the asphalt pavement is considered as an infinite long elastic beam on Kelvin viscous-elastic foundation. The mathematical model of steady response of the beam is established. The relationship between the steady response and the transient response is obtained, an approximate analytic solution of steady response is obtained from the transient response analysis solution. Based on the parameters of road, an example is calculated. The calculation results show that as long as the zone of response is enough far from the initial point, the transient response of the asphalt pavement subjected to some vehicle load is a steady response. Therefore, a simple method is provided for obtaining the asphalt pavement steady response.
Review
2009, 31(3):  1-8.  doi:10.6052/1000-0879-2008-439
Abstract ( 1234 )   PDF (2212KB) ( 640 )
The micro-miniature of electronic devices is greatly promoted by the rapid development of electronics industry. The study on the reliability of the micro-electronic devices is the foundation of designing novel electronic products, and has drawn much attention of researchers. The parameters of mechanical behavior obtained from experiment are the basis of reliability analysis. In this study, the development of micro-moir\'{e} methods is reviewed, covering moir\'{e} interferometry, scanning electronic microscope moir\'{e} methods and their applications to analysis of mechanical behavior of the micro-electronic devices are discussed.
2009, 31(3):  9-15.  doi:10.6052/1000-0879-2008-618
Abstract ( 1338 )   PDF (1419KB) ( 517 )
This paper reviews the latest advances of numerical simulation for gravel packing in horizontal wells. The discussions focus on the following topics: gravel packing process mechanism and technology; calculation model for equilibrium bank height and critical velocity in packing. A description is made on slurry flow in screen/wellbore annuli, carried fluid flow in wash-pipe/screen annuli and fluid transfer between two flow system and fluid leak-off into formation. The mathematical model for bank height in $\alpha$ wave packing, factors affecting horizontal well gravel-pack efficiency and existing problems are also discussed.
Mechanicist
2009, 31(3):  103-105.  doi:10.6052/1000-0879-2009-028
Abstract ( 1662 )   PDF (1160KB) ( 788 )