Wedge Operations and Doubling Operations of Real Toric Manifolds

This paper deals with two things.First,the cohomology of canonical extensions of real topological toric manifolds is computed when coefficient ring G is a commutative ring in which 2 is unit in G.Second,the author focuses on a specific canonical extensions called doublings and presents their various properties.They include existence of infinitely many real topological toric manifolds admitting complex structures,and a way to construct infinitely many real toric manifolds which have an odd torsion in their cohomology groups.Moreover,some questions about real topological toric manifolds related to Halperin's toral rank conjecture are presented.     

Effect of Free‐Stream Turbulence on the Flow Structure near a Wedge and the Windward Side of an Airfoil

The flow structure behind wire grids is studied for flows with a low subsonic velocity, and the effect of grids on the boundarylayer flow structure is considered. It is shown that the meanvelocity inhomogeneity induced by the grid does not disappear until a distance of 925 calibers downstream of the grid is reached. Liquidcrystal thermography combined with hotwire measurements made it possible to find the source of steady largescale streamwise vortex structures in the boundary layer on a wedge and on an airfoil and to determine the parameters of these structures.     

各向异性两相材料尖劈奇性场的非协调元分析

提出了一个基于位移的、分析柱状各向异性两相材料尖劈端部邻域的奇性位移场和应力场问题的非协调元特征分析法. 该方法从柱状扇区的散度定理出发，将柱状扇区控制方程的弱式化为一个与虚功原理相同形式的方程，采用一种新的非协调元技术把所导出的``虚功原理'转化为标准一阶特征方程的求解问题. 非协调元法中，尖劈端部邻域的位移场假定没有采用奇异变换技术，有限元的单元形式是一维的. 将柱状各向异性两相材料尖劈视为``广义平面应变'问题，位移场与坐标z无关，只关注界面端的幂奇异性而不考虑对数奇异性. 运用该方法给出了柱状各向异性两相材料尖劈端部奇性应力指数、奇性位移角分布和应力角分布的算例. 所有的计算结果表明，该方法使用的单元少而且精度较高.     

EFFECTS OF DISLOCATION CONFIGURATION, CRACK BLUNTING AND FREE SURFACES ON THE TRIGGERING LOAD OF DISLOCATION SOURCES

The effects of dislocation configuration,crack blunting and free surfaces on the triggering load of dislocation sources in the vicinity of a crack or a wedge tip subjected to a tensile load in the far field are investigated.An appropriate triggering criterion for dislocation sources is proposed by considering the configurational forces acting on each dislocation.The triggering behaviors of dislocation sources near the tips of a crack and a wedge are compared.It is also found that the blunting of crack tip and the presence of free surfaces near the crack or the wedge have considerable influences on the triggering load of dislocation sources.This study might be of significance to gaining a deeper understanding of the brittle-to-ductile transition of materials.     

The wedge subjected to general tractions: A paradox resolved

A wedge subjected to tractions in proportion tor ⁿ (n≥0), is considered. The stresses in the solutions of the classical theory of elasticity become infinite when the angle of the wedge is ρ or 2ρ. The paradox has been resolved by Dempsey^[4] and T.C.T. Ting^[5] whenn=0. The purpose of this paper is to resolve the paradox whenn>0.     

ANALYSIS OF AN INCOMPRESSIBLE RUBBER WEDGE CONTACTING WITH A RIGID NOTCH

I. INTRODUCTION It is well known that rubber materials are much more important in modern society. It is, therefore,not surprising that a sizable number of investigations have been concerned with the rubber materials.Considerable attention has been paid …     

GENERAL SOLUTION OF PLANE PROBLEM OF PIEZOELECTRIC MEDIA EXPRESSED BY "HARMONIC FUNCTIONS

I.IntroductionBecauseofthecouplingcharacteristicbetweenthemechanicaldeformationandthee1ectricaleffect,piezoelectricmaterialshavebeenwidelyusedintransducersandsmartstructures.Moreandmoreattentionshavebeenpaidonsuchmaterials,andgreatadvanceshavebeenmadeinva…     

方形管内楔形障碍物对火焰结构与传播的影响

通过实验与数值模拟方法对CH4/空气预混火焰在有楔形障碍物的卧式燃烧方管内的传播进行了研究。采用多镜头Cranz Schardin高速摄像机和压力传感器等实验设备获得了高清晰度的障碍物诱导火焰失稳的分幅时序照片以及障碍物背风表面压力变化曲线。数值模拟则基于RANS方法与EDU-Arrhenius燃烧模型,计算结果与实验结果基本相符,反映了火焰在管内传播与变形的详细过程。通过综合分析实验与计算结果,得到了由楔形障碍物导致的火焰加速与变形的内在机理,揭示了火焰传播过程中由层流燃烧向湍流燃烧转捩的本质。     

双材料界面应力分析的局部杂交法

本文用云纹干涉法测取双材料高梁受集中载荷时沿ｘ，ｙ轴的位移场ｕ，ｖ．以其作为界面局部微区的边界条件，用有限元计算此微区内界面上的应力分量．与光弹性及全梁有限元法比较，发现局部杂交法的精度最高．     

Stress singularities near the apex of a cylindrically polarized piezoelectric wedge

Summary In this paper, the stress singularities for a cylindrically polarized piezoelectric wedge are investigated. The characteristic equations are derived analytically by using the extended Lekhnitskii formulation. The piezoelectric material (PZT-4) is polarized in the radial, circular or axial direction, respectively. Similar to the rectilinearly polarized piezoelectric problem, the inplane and antiplane stress fields are uncoupled. The results show the variations of the singularity orders with the changes of the wedge angle, material constants, polarized direction, and the boundary conditions.