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排序方式: 共有298条查询结果,搜索用时 15 毫秒
81.
从菲涅尔-基尔霍夫衍射积分公式出发,运用边界元法数值计算了平凹腔平面镜均匀反射率时倾斜和未倾斜情况下基模的场强分布、相位分布和本征值,同时与高斯反射率平面镜在腔镜倾斜时的情况做了比较。研究表明,腔镜倾斜使激光场模式分布沿发生倾斜的方向向镜边缘偏移,而且在腔镜倾斜较严重时模式分布发生畸变,不再是对称的高斯分布,基模本征值随倾斜角增大而变小,光束远场分布变差。同等条件下,高斯反射率平凹腔腔镜倾斜对谐振腔引起的模畸变小于均匀反射率平凹腔,且基模光场及本征值随镜倾斜的变化关系稍不同于均匀反射率平凹腔。 相似文献
82.
83.
V. A. Bazhenov A. I. Gulyar S. O. Piskunov A. S. Sakharov A. A. Shkril’ 《International Applied Mechanics》2008,44(12):1378-1388
A new method to evaluate the J-integral in finite-element models is developed and implemented. It is shown that in contrast
to well-known approaches, this method ensures the invariance of the J-integral in finite-element solution of linear and nonlinear
problems
Translated from Prikladnaya Mekhanika, Vol. 44, No. 12, pp. 70–82, December 2008. 相似文献
84.
85.
The elastic modulus of a nanocomposite reinforced with nanoclay was studied using the 3D finite-element method. It is widely accepted that interphase between nanoparticle and matrix plays an important role in the performance of the nanocomposite. Thus, a representative volume element (RVE) consisted of three phases (i.e. matrix, interphase and nanoclay) was simulated. In addition, to have a realistic estimation of elastic modulus of the interphase region, the modulus was computed using the available analytical formula. Since the nanoclays have been known as platelets and to investigate the effect of the third dimension, the nanoclay was simulated as a thin cuboid. The effect of various geometrical parameters, such as the change of the nanoclay contact area at a constant volume fraction of nanoclay, the variation of the nanoclay angle in the planes perpendicular and parallel to the loading direction, and the RVE dimensions, on the elastic modulus of a nanocomposite was considered. The results revealed that the increase in contact area of the nanoclay at a constant volume of nanoclay led to an increase in the elastic modulus of the nanocomposite. Furthermore, the change in the angle of nanoclay with respect to the plane parallel to loading direction has considerable effects on the elastic modulus of the nanocomposite, whereas this effect is negligible for the alignment angle perpendicular to the plane of the loading direction. Finally, unlike the previous studies, the results of the finite-element modeling were compared with three-phase theory of Mori–Tanaka. 相似文献
86.
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
87.
The diffuse approximation is presented and applied to natural convection problems in porous media. A comparison with the control volume-based finite-element method shows that, overall, the diffuse approximation appears to be fairly attractive.Nomenclature
H
height of the cavities
-
I
functional
-
K
permeability
-
p(M
i
,M)
line vector of monomials
-
p
T
p-transpose
-
M
current point
- Nu
Nusselt number
- Ri
inner radius
- Ro
outer radius
- Ra
Rayleigh number
-
x, y
cartesian coordinates
-
u, v
velocity components
-
T
temperature
-
M
vector of estimated derivatives
-
t
thermal diffusivity
-
coefficient of thermal expansion
-
practical aperture of the weighting function
-
scalar field
-
(M, M
i
)
weighting function
-
streamfunction
-
kinematic viscosity 相似文献
88.
Yu. I. Lelyukh 《International Applied Mechanics》2007,43(12):1396-1405
Three methods to allow for damage of isotropic materials are discussed. The relations of the theory of deformation along paths
of small curvature are used as equations of state. Rabotnov’s scalar equation is used to study the damage of a material during
thermoviscoelastoplastic deformation. The stress determined by a stress rupture criterion that accounts for the stress mode
is taken as an equivalent stress. An algorithm based on the finite-element method is developed to solve three-dimensional
problems of thermoviscoelastoplasticity with allowance for material damage. The numerical results obtained are compared with
experimental data
__________
Translated from Prikladnaya Mekhanika, Vol. 43, No. 12, pp. 110–121, December 2007. 相似文献
89.
A technique for solving problems of nonlinear continuum mechanics associated with contact interaction, plastic distortion, and continuous and discrete fracture of spatial bodies is developed based on the semianalytic finite-element method generalized to noncanonical bodies. Solutions are obtained to new applied problems in various branches of technology. Compared with the traditional FEM, the technique is highly efficient—the amount of computation needed to solve spatial problems reduces by several orders of magnitude 相似文献
90.
The simulation of electrostatic coupling intra body communication based on the finite element method
In this paper, investigation has been done in the computer simulation of the electrostatic coupling IBC by using the developed finite-element models, in which a.the incidence and reflection of electronic signal in the upper arm model were analyzed by using the theory of electromagnetic wave;b.the finite-element models of electrostatic coupling IBC were developed by using the electromagnetic analysis package of ANSYS software;c.the signal attenuation of electrostatic coupling IBC were simulated under the conditions of different signal frequencies, electrodes directions, electrodes sizes and transmission distances. Finally, some important conclusions are deduced on the basis of simulation results. 相似文献