共查询到20条相似文献，搜索用时 468 毫秒
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A.A. Raptis 《Journal of The Franklin Institute》1983,316(6):445-449
This paper investigates the effects of a magnetic field on the free convective flow of a viscous, incompressible, dissipative fluid through a porous medium, occupying a semi-infinite region of the space bounded by an infinite vertical and porous plate. The plate is subjected to a normal suction velocity and the heat flux at the plate is constant. The magnetic field is of uniform strength and is applied perpendicular to the plate. An analytical solution to the problem is obtained. The influence of the magnetic parameter (M) and permeability parameter (K) is discussed for the case of air (P = 0.71) when the plate is subjected to a constant suction velocity and is being cooled by free convection currents. 相似文献
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纤维增强塑料(FRP)与混凝土的粘结性能是混凝土结构外贴FRP板材这一加固技术的重要研究课题。本文通过对混凝土表面粘贴FRP板的单剪搭接接头进行三维有限元模拟,得出了胶和混凝土中在加载端和自由端附近的各应力分量的分布曲线以及FRP板中沿板长度方向的应力分布曲线,从而分析板宽对FRP-混凝土粘结界面应力分布的具体影响,以期为进一步的相关研究提供参考。研究结果表明:(1)沿着板宽度方向应力存在着严重的不均匀性;(2)随着板宽的增加,使得应力沿着板宽的方向渐趋于均匀,因而有利于应力的传递;(3)当宽度比较大时,易发生自由端混凝土的拉剪破坏。 相似文献
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E.E. Gdoutos 《Journal of The Franklin Institute》1981,312(5):361-371
An analysis of the plastic enclaves developed around the end points of rigid fiber inclusions embedded in an elastic plate is undertaken. The plate is subjected to a uniform uniaxial stress at any angle of inclination with the axis of the fiber. It is assumed that the material of the plate is elastic-perfectly plastic and that the deformations are small. A singular solution of the stress field in the vicinity of the end points of the fiber is used in conjunction with the Mises yield criterion to obtain the radius of the plastic zone under conditions of plane strain and generalized plane stress. The dependence of the size and shape of the plastic deformation on the orientation of the fiber, the Poisson's ratio of the plate and the state of stress (plane strain or generalized plane stress) is established. 相似文献
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大型储罐第一圈壁板接管的焊接及热处理 总被引：1，自引：0，他引：1
文章介绍如何对大型储罐第一圈壁板的开孔处进行刚性加固以减小热处理后由于大量焊接应力释放导致的壁板严重变形,加固板采用连接板补偿的形式安装在壁板上。并且介绍在施工现场预制开孔板以降低施工成本,热处理炉采用地下形式制作,具有良好的保温效果。 相似文献
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Betzalel Avitzur Walter C. Hahn Samy Iscovici 《Journal of The Franklin Institute》1975,299(5):339-358
A variety of mathematical models may be used to analyse plastic deformation during a metal-forming process. One of these methods—limit analysis—places the estimate of required power between an upper bound and a lower bound. The upper and lower bound analyses are designed so that the actual power or forming stress requirement is less than that predicted by the upper bound and greater than that predicted by the lower bound. Finding a lower upper bound and a higher lower bound reduces the uncertainty of the actual power requirement. Upper and lower bounds will permit the determination of such quantities as required forces, limitations on the process, optimal die design, flow patterns, and prediction and prevention of defects.Fundamental to the development of both upper bound and lower bound solutions is the division of the body into zones. For each of the zones there is written either a velocity field (upper bound) or a stress field (lower bound). A better choice of zones and fields brings the calculated values closer to actual values.In the present work, both upper and lower bound solutions are presented for axisymmetric flow through conical converging dies. For the upper bound triangular velocity fields have been solved and compared to previously published work on spherical velocity fields. It is found that each type provides a lower solution over a part of the range of process variables. A previously published lower bound solution for axisymmetric flow is refined. 相似文献
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A statistical analysis is presented for steady creep bending in a beam, where the material parameters are random processes along the neutral axis arising from random fluctuations in temperature and imperfection density. Analytical and numerical results are presented for the statistical properties of the normal stress and lateral velocity. It is found that whereas the normal stress shows very little random fluctuation the lateral velocity is highly random. The statistics of the lateral velocity generally show a significant dependence on the nominal value of the creep power and on the position along the neutral axis. 相似文献
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In this research, linear and non-linear stability behaviour of a thin circular FGM plate subjected to the uniform temperature rise and the constant angular velocity loadings is analyzed. Properties of the FGM media are distributed across the thickness based on a power law form. Each property of the metal or ceramic constituents is considered to be the function of temperature based on the Touloukian model. General equilibrium equations for such conditions are obtained based on the classical plate theory. At first, the non-linear governing equations are established in a complete asymmetrical form. After that, two different analytical methods are presented to study the bifurcation behaviour. Existence of bifurcation phenomenon is examined. Pre-buckling analysis is performed for a plate with the immovable clamped edge. Stability equations are obtained based on the adjacent equilibrium criterion. The resulted equations are solved via the two distinct methodologies, i.e. the exact solution in terms of Coulomb wave functions and the power series method. A non-linear solution is also presented to detect the equilibrium path of the heated rotating FGM plate. It is found that the angular speed may stabilize the homogeneous circular plate which buckles during uniform heating. Furthermore, snapping may occur for FGM plates under the simultaneous action of heating and uniform rotation. 相似文献
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全球板块运动对板块边界带应力场的影响 总被引：1，自引：0，他引：1
将全球板块边界带分别按照不同的宽度加以界定 ,计算了全球板块边界应力场的长、短波分量 ,讨论了应力场短波分量对观测应力场的相对贡献 ,分析了其与板块边界相互运动类型的相关性 .在收敛型边界带 ,俯冲板片推 (拉 )力是驱动板块运动的主要力源 ,仅仅洋脊推力不能主导板块的应力场形态 ;同时 ,大陆板块之间的碰撞力对板块运动具有重要意义 .计算结果还显示板块边界带参考半宽度以不大于 2 0 0km较为合适 . 相似文献
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池壁板的结构形式一般有两种:两壁板间有搭接钢筋和两壁板间无搭接钢筋。前一种壁板的横向非预应力钢筋可承受部分拉应力,但外露筋易锈蚀,壁板间接缝混凝土捣固不易密实、府加强振捣。 相似文献
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This paper presents a solution for a semi-infinite plate containing a deep semi-elleptic edge notch when the plate is under a uniaxial tension parallel to the edge. The solution is a direct solution composed of three parts, which is developed from Howland's method of successive approximations through two significant modifications. It is found that the present solution is more adaptable to numerical computation with regard to the depth ratio of the notch than other solutions known to exist. Numerical values of the stress concentration are given for a depth ratio up to 10. 相似文献
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R. Ponalagusamy R. Tamil Selvi A.K. Banerjee 《Journal of The Franklin Institute》2012,349(5):1681-1698
The effects of rheological behavior of blood and pulsatility on flow through an artery with stenosis have been investigated. Blood has been represented by a non-Newtonian fluid obeying Herschel–Bulkley equation. Using the Reynolds number as the perturbation parameter, a perturbation technique is adopted to solve the resulting quasi-steady non-linear coupled implicit system of differential equations. Analytical expressions for velocity distribution, wall shear stress, volumetric flow rate and the mean flow resistance have been obtained. It is observed that the wall shear stress and flow resistance increase for increasing value of yield stress with other parameters held fixed. One of the remarkable results of the present analysis is not only to bring out the effect of the size of the stenosis but also to study the influence of the shape of the stenosis. The change in the shape of the stenosis brings out a significant change in the value of flow resistance but it has no effect on the variation of wall shear stress except shifting the point (where it attains its maximum value) towards downstream. It is pertinent to point out that pulsatile flow of Newtonian fluid, Bingham plastic fluid and Power-law fluid become particular cases of the present model. The present approach has general validity in comparison with many mathematical models developed by others and may be applied to any mathematical model by taking into account of any type of rheological property of blood. The obtained velocity profiles have been compared with the experimental data and it is observed that blood behaves like a Herschel–Bulkley fluid rather than Power-law and Bingham fluids. Finally, some biorheological applications of the present model have briefly been discussed. 相似文献
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Yu Chen 《Journal of The Franklin Institute》1975,300(3):185-191
The dynamic radial stress distribution in a circular hollow cylinder, bonded to a rigid core at its inner surface and prevented from outward displacement by a smooth rigid cylindrical wall, due to a rotational motion with a variable angular velocity, is analyzed.The stress as a function of radial distance and time is determined. A sample calculation shows that the stress changes from tension at the inner surface to compression at the outer surface, as would be expected. The variation of stress vs radial distance is plotted for several instants of time. Also, the stress vs time for various radial positions is plotted. 相似文献
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We developed a new method for releasing viable cells from affinity-based microfluidic devices. The lumen of a microchannel with a U-shape and user-designed microstructures was coated with supported lipid bilayers functionalized by epithelial cell adhesion molecule antibodies to capture circulating epithelial cells of influx solution. After the capturing process, air foam was introduced into channels for releasing target cells and then carrying them to a small area of membrane. The results show that when the air foam is driven at linear velocity of 4.2 mm/s for more than 20 min or at linear velocity of 8.4 mm/s for more than 10 min, the cell releasing efficiency approaches 100%. This flow-induced shear stress is much less than the physiological level (15 dyn/cm2), which is necessary to maintain the intactness of released cells. Combining the design of microstructures of the microfluidic system, the cell recovery on the membrane exceeds 90%. Importantly, we demonstrate that the cells released by air foam are viable and could be cultured in vitro. This novel method for releasing cells could power the microfluidic platform for isolating and identifying circulating tumor cells. 相似文献
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A maximum principle is formulated and validated for the vibration control of an annulus plate with the control forces acting on the boundary. In addition, the maximum principle can be applied to plates with multiply connected domains. The performance index is specified as a quadratic functional of displacement and velocity along with a suitable penalty term involving the control forces. Using this index an explicit control law is derived with the help of an adjoint variable satisfying the adjoint differential equation and certain terminal conditions together with the proposed maximum principle. The implementation of the theory is presented and the effectiveness of the boundary control is investigated by a numerical example. 相似文献
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This paper presents a research for Marangoni convection driven by a power-law temperature gradient. It is assumed that the surface tension is quadratic functions of the temperature and the effects of power law viscosity on temperature field into account by assuming that the temperature field is similar to the velocity field. The Navier–Stokes equations and the heat equation with modified Fourier's law heat conduction (Zheng's Model) for power law fluid media are reduced to two nonlinear ordinary differential equations and the solutions are presented numerically. The effects of the Power-law Number and the Marangoni Number on the interfacial velocity and the interfacial temperature gradient are presented in tabular form and the effects of various parameters on the velocity and temperature fields are analyzed and discussed in detail. 相似文献
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在工矿企业中,风机作为一种动力设备是耗能大户,是人们认为没有必要进行速度控制的设备。人们一般采用交流异步电动机恒速运转拖动,当生产需要调节风量时往往采用调节节流阀或挡板,这种控制虽然简单,但并不节能。采用电动机调速改变风量的方法已被广泛地应用到生产中,可以节约大量的电能。 相似文献
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The propagation of elastic waves in a heterogeneous bar of variable cross-sectional area is investigated via use of the method of characteristics andthe Laplace transform technique. The Young's modulus and density are assumed to be representable as either power law or exponential distributions in the axial coordinate. The transform method is used to establish an infinite number of multi-parameter solutions in closed form for either a stress, velocity or displacement type boundary condition. The numerical characteristic computations show excellent agreement when compared to the transform solutions, and are then used to obtain additional solutions not attainable by the transform method. Detailed results and conclusions for a bar of ogival cross-section are given for a wide range of inhomogeneity. 相似文献
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Steven J. Sackett James M. Kelley Peter P. Gillis 《Journal of The Franklin Institute》1977,304(1):47-63
Using our constitutive theory for polycrystalline plasticity, we have calculated characteristic yield conditions for several sample materials in which the dependence of the dislocation velocity on stress is given by an empirical power function. The shape of the yield surfaces for these materials varies resembling that of von Mises when the stress exponent is small and that of Tresca when the exponent is large. Additional examples illustrate the ability of the proposed theory to model such phenomena as the development of anisotropy during plastic deformation, material hardening and softening, the occurrence of upper and lower yield points, and a Bauschinger effect. 相似文献