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992.
Summary The bending of a finite-length beam that lies on a rigid, rough, flat foundation and interacts with it in accordance to the
dry friction law is considered. Loading by bending moments applied at the ends of the beam is studied in detail. The problem
is found to be a self-similar one. For small moments, the central part of the beam remains undeflected, and the problem reduces
to the solution of an infinite system of algebraic equations. Large moments deflect the entire length of the beam, and the
problem partly loses its self-similarity. In this case, the problem reduces to the solution of a successively decreasing number
of ordinary differential equations along with some algebraical equations. The solution for the latter case provides initial
conditions for the former one. This permits to obtain a solution for any value of the moment.
Received 5 November 1996; accepted for publication 27 January 1997 相似文献
993.
Lei Xiaoyan 《Acta Mechanica Solida Sinica》1994,7(1):87-96
This paper presents a new boundary integral equatiòn for two-dimensional elasticity with the stress component σ_(ij)t_it_j as one of the boundary values,where t_i is the direction cosine of the tangent on the boundary.This form of BEM hasan advantage in that the stress component σ_(ij)t_it_j on the boundary can be calculateddirectly from the numerical solution.The present formulation for plane problems usestwo kernels,the one is logarithmically singular and the other is 1/r singular.Theeffectiveness of the approach is also discussed through test examples. 相似文献
994.
An extension of the Elastica theory is developed to study the large deflection of an elastic-perfectly plastic horizontal
cantilever beam subjected to a vertical concentrated force at its tip. The entire process is divided into four stages: I.elastic
in the whole cantilever; II.loading and developing of the plastic region; III.unloading in the plastic region; and IV.reverse
loading. Solutions for stages I and II are presented in a closed form. A combination of closed-form solution and numerical
integration is presented for stage III. Finally, stage IV is qualitatively studied. Computed results are given and compared
with those from small-deflection theory and from the Elastica theory. 相似文献
995.
基于多孔介质理论和弹性梁的大挠度理论,并考虑轴向变形,在孔隙流体仅沿轴向扩散的假设下,建立了微观不可压饱和多孔弹性梁大挠度弯曲变形的一维非线性数学模型.在此基础上,忽略饱和多孔弹性梁的轴向应变,并利用Galerkin截断法,研究了两端可渗透的简支饱和多孔弹性梁在突加横向均布载荷作用下的拟静态弯曲,给出了饱和多孔梁弯曲时挠度、弯矩和轴力以及孔隙流体压力等效力偶等沿轴线的分布曲线.揭示了大挠度非线性和小挠度线性模型的结果差异,指出大挠度非线性模型的结果小于相应小挠度线性模型的结果,并且这种差异随着载荷的增大而增大.计算表明:当无量纲载荷参数q>5时,应该采用大挠度非线性数学模型进行研究. 相似文献
996.
997.
The dynamic thermomechanical problem for thin-walled laminated elements is formulated based on the geometrically linear theory and Kirchhoff–Love hypotheses. A simplified model of vibrations and dissipative heating of structurally inhomogeneous inelastic bodies under harmonic loading is used. The mechanical properties of materials are described using strain-dependent complex moduli. A nonstationary vibration-heating problem is solved. The dissipative function, derived from the stationary solution, is used to specify internal heat sources. The amplitude–frequency characteristics and spatial distributions of the main field variables are studied for a sandwich beam subjected to forced vibrations 相似文献
998.
S. D. Algazin 《Journal of Applied Mechanics and Technical Physics》2006,47(4):573-581
The problem of free vibrations of a beam with free ends of variable cross section and mass, from which point masses (oscillators)
are suspended by bars, is considered. It is shown that parametric resonances can occur in this oscillating system. Numerical
examples showing the efficiency of the calculation method proposed are given.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 47, No. 4, pp. 135–144, July–August, 2006. 相似文献
999.
Modeling Variable Density Flow and Solute Transport in Porous Medium: 1. Numerical Model and Verification 总被引:1,自引:0,他引:1
A new numerical model for the resolution of density coupled flow and transport in porous media is presented. The model is based on the mixed hybrid finite elements (MHFE) and discontinuous finite elements (DFE) methods. MHFE is used to solve the flow equation and the dispersive part of the transport equation. This method is more accurate in the calculation of velocities and ensures continuity of fluxes from one element to the adjacent one. DFE is used to solve the convective part of the transport equation. Combined with a slope limiting procedure, it avoids numerical instabilities and creates a very limited numerical dispersion, even for high grid Peclet number.Flow and transport equations are coupled by a standard iterative scheme. Residual based criterion is used to stop the iterations. Simulations of an unstable equilibrium show the effects of the criteria used to stop the iterations and the stopping criterion in the solver. The effects are more important for finer grids than for coarser grids.The numerical model is verified by the simulation of standard benchmarks: the Henry and the Elder test cases. A good agreement is found between the revised semianalytical Henry solution and the numerical solution. The Elder test case was also studied. The simulations were similar to those presented in previous works but with significantly less unknowns (i.e. coarser grids). These results show the efficiency of the used numerical schemes. 相似文献
1000.
利用离子束增强沉积技术,在将Ti用Ar^+束溅沉积到淬火态9Cr18Mo不锈轴承钢表面的同时,分别用Ar^+,N^+和C^+轰击试样表面,制取了增强沉积的表面改性层 相似文献