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71.
高速荷载下多孔饱和地基的动力响应 总被引:8,自引:0,他引:8
研究高速荷载作用下梁与多孔饱和半空间的动力响应。由Fourier变换求解多孔饱和固体的动力基本方程,根据梁与半空间的接触条件得出多孔饱和半空间上梁的垂直位移的表达式。文中的数值算例考虑了荷载移动速度对梁的动力位移的影响,并与相应的弹性半空间问题作了对比。从算例中可以发现荷载移动速度对动力位移有很大的影响,当移动速度与半空间的表面波速相近时,地面会当产生很大的振动,同时还发现当速度大于介质的剪切波速时,多孔饱和半空间上梁的动力响应与弹性半空间上梁的动力响应有很大的差别。 相似文献
72.
Shu-Xian Gu 《Acta Mechanica Solida Sinica》1988,1(4):369-381
In this paper, we treat the nonlinear stability problem of shallow spherical shells with large values ofk(k=12(1–v) · 2f/h,f = shell rise,h = shell thickness) under the action of uniformly distributed line load along a circle concentric with the shell boundary. Load-deflection curves are computed at successive increments of uniformly distributed line loads by using both cubic B-spline approximations and iterative techniques. Our algorithm yields fairly good convergent results for values ofk as large as 400. The limiting case in which shells are loaded along a circle of small radius has been specially investigated and the computed critical loads are compared with those obtained with central point loads by other authors. 相似文献
73.
E. V. Ermanyuk N. V. Gavrilov 《Journal of Applied Mechanics and Technical Physics》2005,46(6):800-806
The hydrodynamic loads due to the interaction of a small-amplitude internal solitary wave with a submerged circular cylinder
in a two-layer system of miscible fluids were studied experimentally. The dependence of the internal-wave transmission coefficient
on the position of the center of the cylinder relative to the pycnocline and on the ratio of the cylinder diameter to the
fluid-layer thickness was obtained. The effects of the pycnocline thickness and the depth of the center of the cylinder on
the value of the hydrodynamic loads were studied. Visualization of the flow structure was performed.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 6, pp. 36–44, November–December, 2005. 相似文献
74.
Summary A fundamental solution, to be used in reciprocal theorem for the solutions of axially symmetric transient problem of elastodynamics,
is presented. A cylindrical cavity problem has been solved to check the formulation. The strong singularity of the resulting
integral equation for this problem has been reduced to the weak form. The new formulation provides the initial velocity on
the surface for a transient loading. Some differences have been introduced for the use of generalized functions. 相似文献
75.
V. I. Grabovskii 《Fluid Dynamics》2004,39(4):540-550
The optimum design of the cylindrical outer contours of a gas journal bearing is obtained using the methods of the calculus of variations with allowance for the lubricant leakage through the bearing ends and the feeder slot when the lubricant mass in the working gap is conserved. The variational problem of designing the clearance shape giving the maximum bearing load capacity is formulated and solved. A modified Elrod-Burgdorfer condition for the pressure is used. 相似文献
76.
In order to describe the basic phenomenon of miscible grout propagation during the injection in a saturated and deformable porous medium, a general mathematical model was proposed, which accounts for the existing coupling between the fluid flow analysis, the miscible grout transport, and the solid skeleton deformation, leading to a realistic prediction of the injected zone. The development of the model was made concurrently with laboratory experiments to determine the model parameters. This paper describes the determination of the longitudinal dispersivity during the transport of a micro-cement grout injected in a one-dimensional soil column, by relying on image processing analysis. The application concerned here is the injection of soils for improving their properties, that is, to reduce permeability, increase mechanical strength or reduce the deformability. The longitudinal dispersion coefficient is an essential parameter governing the mixing process and the evolution of the transition zone, and thus the injection efficiency. Finally, the comparison between simulated results from the developed model and experimental data, essential to validate the model from a phenomenological standpoint, is made. 相似文献
77.
Summary The article presents a fast numerical algorithm for calculating the response of a halfspace under any surface loads. Under
certain conditions there exists an analytical solution to the problem in the Fourier domain. To get the desired response,
a numerical inverse Fourier transform of this analytic solution has to be made. By using a wavelet decomposition, the proposed
algorithm can reduce the calculation time significantly, thus allowing the computation of complex problems. As an example,
the response of the beam-halfspace coupled system under moving load is presented.
Received 6 March 1997; accepted for publication 20 May 1997 相似文献
78.
The physical mechanisms of development of hydrodynamic instability during high-velocity impact are analyzed analytically and using numerical simulation. A new mechanism of development of instability based on the assumption of the existence of initial perturbations on the surfaces of the colliding plates is proposed. The progressive displacement of the maximum of the specific surface mixed mass from the shortwave to the longwave spectrum range and the self-similarity of the variation of the interface are established. 相似文献
79.
S. Madruga C. Pérez–García G. Lebon 《Theoretical and Computational Fluid Dynamics》2004,18(2-4):277-284
We study theoretically the stability of two superposed fluid layers heated laterally. The fluids are supposed to be immiscible, the interface undeformable and of infinite horizontal extension. Combined thermocapillary and buoyancy forces give rise to a basic flow when a temperature difference is applied. The calculations are performed for a melt of GaAs under a layer of molten B2O3, a configuration of considerable technological importance. Four different flow patterns and five temperature configurations are found for the basic state in this system. A linear stability analysis shows that the basic state may be destabilized by oscillatory motions leading to the so-called hydrothermal waves. Depending on the relative height of the two layers these hydrothermal waves propagate parallel or perpendicular to the temperature gradient. This analysis reveals that these perturbations can alter significantly the liquid flow in the liquid-encapsulated crystal growth techniques. PACS 47.20.Dz, 47.20.Bp, 47.54.+r, 47.27.Te, 44.25.+f, 47.20.Ma 相似文献
80.