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991.
Cafer Caliskan 《组合设计杂志》2017,25(12):581-584
In this article, it is shown that there is a partitioning of the set of 3‐arcs in a projective plane of order three into nine pairwise disjoint Steiner triple systems of order 13. 相似文献
992.
H. Houcine Yu. D. Chashechkin P. Fraunié H. J. S. Fernando A. Gharbi T. Lili 《国际流体数值方法杂志》2012,68(4):451-466
Numerical simulations of two‐dimensional stratified flow past an obstacle (thin vertical strip) were performed at relatively low Reynolds numbers. A finite differences solver was adopted to simultaneously solve Navier–Stokes equations together with transport equations for salinity (stratifying agent), and the standard Smagorinsky turbulent closure scheme was called in whenever necessary to account for turbulence. The emphases were on the evaluation of code for unsteady stratified flow applications as well as identification of transient and steady internal‐wave processes during flow past obstacles. Simulations were compared with laboratory experiments, where observations were made using a high resolution Schlieren technique and conductivity probes. Blocking was observed upstream of the obstacle, surrounded by near‐zero frequency internal waves, the phase lines of which joined those of lee waves through a transition zone in the proximity of the obstacle. This pattern was preceded by initial transients of the starting flow in which propagating internal waves played a dominant role. Confluence of isopycnals passing over/under the obstacle in the wake led to interesting flow phenomena, including the radiation of internal waves. The numerical simulations were in good agreement with observations, except that some phenomena could not be captured due to resolution issues of either numerical or experimental techniques. The efficacy of the code in point for stratified flow calculations with relevance to the atmosphere and oceans was confirmed. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
993.
在大变形弹塑性本构理论中,一个基本的问题是弹性变形和塑性变形的分解.通常采用两种分解方式,一是将变形率(或应变率)加法分解为弹性和塑性两部分,其中,弹性变形率与Kirchhoff应力的客观率通过弹性张量联系起来构成所谓的次弹性模型,而塑性变形率与Kirchhoff应力使用流动法则建立联系;另一种是基于中间构形将变形梯度进行乘法分解,它假定通过虚拟的卸载过程得到一个无应力的中间构形,建立所谓超弹性-塑性模型.研究了基于变形梯度乘法分解并且基于中间构形的大变形弹塑性模型所具有的若干性质,包括:在不同的构形上,塑性旋率的存在性、背应力的对称性、塑性变形率与屈服面的正交性以及它们之间的关系.首先,使用张量函数表示理论,建立了各向同性函数的若干特殊性质,并导出了张量的张量值函数在中间构形到当前构形之间进行前推后拉的简单关系式.然后,基于这些特殊性质和关系式,从热力学定律出发,建立模型在不同构形上的数学表达,包括客观率表示的率形式和连续切向刚度等,从而获得模型所具有的若干性质.最后,将模型与4种其他模型进行了比较分析. 相似文献
994.
995.
Gulyaev V. I. Gaidaichuk V. V. Chernyavskii A. G. Scialino L. 《International Applied Mechanics》2003,39(9):1084-1088
A structural analysis of a large orbital antenna is reduced to stress–strain, stability, and modal analyses of its prestressed structure. The numerical results obtained by the finite-element method are presented 相似文献
996.
环空钻柱三维二重非线性动力学问题的研究 总被引:3,自引:0,他引:3
通过对大挠度钻柱受力变形特点及其环空旋转状态下与井壁接触机理的分析,根据动力学原理,建立和进一步完善钻柱与井壁动态摩擦接触模型.根据有限元理论,提出了Wilson-θ法与Newton-Raphson法相结合的模式,解决钻柱二重非线性动力学问题.计算分析结果说明,文中理论模型是可行的,不仅更完善,而且更简便;动态非线性效应分析得到了与静态分析相似的结论;钻柱与井壁各种接触形式或并存或交替都有可能;转速较高时动态影响不容忽视. 相似文献
997.
提出各向同性扁壳比拟法,分析满足条件D_3=D_(12)=(D_1D_2)~(1/2)的正交异性扁壳大挠度弯曲和超屈曲问题,导出了正交异性扁壳与各向同性扁壳之间,两种不同正交异性扁壳之间坐标变量、扁壳厚度和曲率半径、荷载、挠度、转角、弯矩、扭矩、中面应力的等价关系式,还证明了等价正交异性扁壳的几个等价不变量。 相似文献
998.
This paper studies the very large deflection behavior of prismatic and non-prismatic cantilever beams subjected to various types of loadings. The formulation is based on representing the angle of rotation of the beam by a polynomial on the position variable along the deflected beam axis. The coefficients of the polynomial are obtained by minimizing the integral of the residual error of the governing differential equation and by applying the beam’s boundary conditions. Several numerical examples are presented covering prismatic and non-prismatic cantilever beams subjected to uniform, non-uniform distributed loads and tip concentrated loadings in vertical and horizontal directions. The loads considered in this study are restricted to the non-follower type loads. Cases with different loadings and geometries are compared with MSC/NASTRAN computer package. However, for some very large deflection case, the MSC/NASTRAN failed to predict the deflected shape due to divergence problems. 相似文献
999.
混合层流场的特性及其大涡结构的研究 总被引:2,自引:0,他引:2
对50年代以来尤其是近10年来有关混合层的研究成果,特别是有关大涡拟序结构的成果进行了综述,为进一步开展混合层的研究提供参考 相似文献
1000.
Z.Y. Gao Tongxi Yu D. Karagiozova 《力学学报》2007,23(1):65
Finite element simulations are carried out to examine the mechanical behavior of the metallic hollow sphere (MHS) material during their large plastic deformation and to estimate the energy absorbing capacity of these materials under uniaxial compression. A simplified model is proposed from experimental observations to describe the connection between the neighboring spheres, which greatly improves the computation efficiency. The effects of the governing physical and geometrical parameters are evaluated; whilst a special attention is paid to the plateau stress, which is directly related to the energy absorbing capacity. Finally, the empirical functions of the relative material density are proposed for the elastic modulus, yield strength and plateau stress for FCC packing arrangement of hollow spheres, showing a good agreement with the experimental results obtained in our previous study. 相似文献