共查询到20条相似文献,搜索用时 27 毫秒
1.
In this paper, a boundary element scheme for arbitrary elastic thin shells is elaborated, Based on BEM of 3D linear elasticity
and Kirchhoff's hypothesis, boundary integral equations for shells are deduced. As a result, only Kelvin's solution is used,
the difficulty in finding a fundamental solution of arbitrary shells is successfully avoided.
The project supported by National Natural Science Foundation of China 相似文献
2.
Some applications of boundary element methods, boundary element-finite element coupling techniques in elasto-plastic stress analysis 总被引:1,自引:0,他引:1
In this paper some research works of author's group on boundary element method for linear elastic and elasto-plastic problems are briefly summarized. The BE subrogions method and BE-FE coupling techniques are introduced, and some idea of the error estimation of BE solutions is presented.This work is supported by the National Natural Science Foundation of China. 相似文献
3.
With the equipment of the SHPB and the gas gun, an experimental study on the elastic wave propagation of framed rods made of 35CrMnSi under impact load is made. The theoretical results by the generalized characteristic line are compared with the experimental ones. Beneficial conclusions are obtained.The project is supported by the Natural Science Foundation of China and the Natural Science Foundation of Shanxi Province. 相似文献
4.
陈山林 《应用数学和力学(英文版)》1998,19(3):227-235
I.IntroductionDishedshallowshellsareakindofthinshellswhichconsistofashallowconicalshellwithacircularplateatthecenterregion.Intheself~controlsystemofprecisioninstrumellts,thesnap-bucklingphenomenonofdishedshallowshellsisusuallyusedasacontrolinformation.Becauseofthedifficultiesinthenon-linearanalysis,thesnap-bucklingproblemofdishedshallowshellshasneverbeenattempted.Atpresent,thedesignforthesnap-bucklingofdishedshallowshellshasbeendonemainlybasedonexperienceandexperimentsl'],butlackenoughtheoret… 相似文献
5.
Boundary element method for moving and rolling contact of 2D elastic bodies with defects 总被引:2,自引:0,他引:2
A scheme of boundary element method for moving contact of two-dimensional elastic bodies using conforming discretization is
presented. Both the displacement and the traction boundary conditions are satisfied on the contacting region in the sense
of discretization. An algorithm to deal with the moving of the contact boundary on a larger possible contact region is presented.
The algorithm is generalized to rolling contact problem as well. Some numerical examples of moving and rolling contact of
2D elastic bodies with or without friction, including the bodies with a hole-type defect, are given to show the effectiveness
and the accuracy of the presented schemes.
The project supported by the National Natural Science Foundation of China (19772025) 相似文献
6.
Using a sub-regional boundary element method, an algorithm for the two-dimensional elastic bodies with a closed crack loaded
by a moving contact elastic body is proposed. Since the extent and status of the contact surface of two elastic bodies and
the crack within the body are all not known in advance, a double iterative contact algorithm is used. The BEM program for
solving the closed crack problems is developed, some numerical examples are calculated, and the results of the center crack
cases are shown to be in good agreement with the analytical solution in the classical fracture mechanics. In the condition
of friction and non-friction, some coupling computational results of the SIF for the closed crack, with different angles and
loaded by a moving contact elastic body, are also obtained by a numerical computation.
The project supported by the National Natural Science Foundation of China (10172053) and NJTU Foundation of China (PD-157) 相似文献
7.
Using strain energy-based prediction of effective elastic properties in topology optimization of material microstructures 总被引:1,自引:0,他引:1
Weihong Zhang Gaoming Dai Fengwen Wang Shiping Sun Hicham Bassir 《Acta Mechanica Sinica》2007,23(1):77-89
An alternative strain energy method is proposed for the prediction of effective elastic properties of orthotropic materials
in this paper. The method is implemented in the topology optimization procedure to design cellular solids. A comparative study
is made between the strain energy method and the well-known homogenization method. Numerical results show that both methods
agree well in the numerical prediction and sensitivity analysis of effective elastic tensor when homogeneous boundary conditions
are properly specified. Two dimensional and three dimensional microstructures are optimized for maximum stiffness designs
by combining the proposed method with the dual optimization algorithm of convex programming. Satisfactory results are obtained
for a variety of design cases.
The project supported by the National Natural Science Foundation of China (10372083, 90405016), 973 Program (2006CB601205)
and the Aeronautical Science Foundation (04B53080). The English text was polished by Keren Wang. 相似文献
8.
According to the classical elastic theory, there is always a discontinuity of rotation angle on the interface between different
materials. This illogic result can be overcome by the strain gradient plasticity theory. In the light of this theory, there
is a group of boundary layer solutions near the interface, which have made important adjustment of the classical results.
This project is supported by National Natural Science Foundation of China (19891180). 相似文献
9.
Based on the theory of elastic dynamics, multiple scattering of elastic waves and dynamic stress concentrations in fiber-reinforced
composite are studied. The analytical expressions of elastic waves in different regions are presented. The mode coefficients
of elastic waves are determined in accordance with the continuous conditions of displacement and stress on the boundary of
the multi-interfaces. By using the addition theorem of Hankel functions, the formula of scattered wave fields in different
local coordinates are transformed into those in one local coordinate to determine the unknown coefficients and dynamic stress
concentration factors (DSCFs). The influences of the distance between two inclusions, material properties and structural size
on the DSCFs near the interfaces are analyzed. As examples, the numerical results of DSCFs near the interfaces for two kinds
of fiber-reinforced composites are presented and discussed.
The project supported by the National Natural Science Foundation of China (19972018) 相似文献
10.
Yuan Si 《Acta Mechanica Sinica》1991,7(3):283-288
In this paper, a number of ordinary differential equation (ODE) conversion techniques for transformation of nonstandard ODE
boundary value problems into standard forms are summarised, together with their applications to a variety of boundary value
problems in computational solid mechanics, such as eigenvalue problem, geometrical and material nonlinear problem, elastic
contact problem and optimal design problems through some simple and representative examples. The advantage of such approach
is that various ODE boundary value problems in computational mechanics can be solved effectively in a unified manner by invoking
a standard ODE solver.
The project is supported by National Natural Science Foundation of China. 相似文献
11.
BEM for simulation of a 2D elastic body with randomly distributed circular inclusions 总被引:7,自引:0,他引:7
Based on our 2D BEM software THBEM2 which can be applied to the simulation of an elastic body with randomly distributed identical
circular holes, a scheme of BEM for the simulation of elastic bodies with randomly distributed circular inclusions is proposed.
The numerical examples given show that the boundary element method is more accurate and more effective than the finite element
method for such a problem. The scheme presented can also be successfully used to estimate the effective elastic properties
of composite materials.
Project supported by the National Natural Science Foundation of China (No. 19772025). 相似文献
12.
Zhao Hanzhong 《Acta Mechanica Solida Sinica》2001,14(4):306-311
The pressure reflected from a bi-laminated piezoelectric plate has been determined using the Thomson-Haskell matrix method.
The plate is composed of a piezoelectric layer with grounded vacuum and an elastic layer in contact with the fluid. An incident
plane wave in the fluid medium strikes the plate at different angles. The required electric potential across the piezoelectric
layer to cancel the reflection from the fluid/elastic boundary has been determined for the piezoelectric material PZT-5 at
various thicknes parameters and incident frequencies.
Project supported by the National Natural Science Foundation of China (No. 10172039). 相似文献
13.
An embedded cell model is presented to obtain the effective elastic moduli for three-dimensional two-phase composites which
is an exact analytic formula without any simplified approximation and can be expressed in an explicit form. For the different
cells such as spherical inclusions and cracks surrounded by sphere and oblate ellipsoidal matrix, the effective elastic moduli
are evaluated and the results are compared with those from various micromechanics models. These results show that the present
model is direct, simple and efficient to deal with three-dimensional two-phase composites.
The project supported by the National Natural Science Foundation of China (No. 19704100) and the National Natural Science
Foundation of Chinese Academy of Sciences (No. KJ951-1-201) 相似文献
14.
H. Xiao 《Journal of Elasticity》1995,39(1):47-73
By means of the combined invariance restrictions due to material frame-indifference and material symmetry, the present paper provides general reduced forms for non-polynomial elastic constitutive equations of all 32 classes of crystals and transversely isotropic solids.Project supported by National Natural Science Foundation and National Postdoctoral Science Foundation of China. 相似文献
15.
Both the orthotropy and the stress concentration are common issues in modern structural engineering. This paper introduces
the boundary element method (BEM) into the elastic and elastoplastic analyses for 2D orthotropic media with stress concentration.
The discretized boundary element formulations are established, and the stress formulae as well as the fundamental solutions
are derived in matrix notations. The numerical procedures are proposed to analyze both elastic and elastoplastic problems
of 2D orthotropic media with stress concentration. To obtain more precise stress values with fewer elements, the quadratic
isoparametric element formulation is adopted in the boundary discretization and numerical procedures. Numerical examples show
that there are significant stress concentrations and different elastoplastic behaviors in some orthotropic media, and some
of the computational results are compared with other solutions. Good agreements are also observed, which demonstrates the
efficiency and reliability of the present BEM in the stress concentration analysis for orthotropic media.
The project supported by the Basic Research Foundation of Tsinghua University, the National Foundation for Excellent Doctoral
Thesis (200025) and the National Natural Science Foundation of China (19902007). The English text was polished by Keren Wang. 相似文献
16.
In this paper, the dynamic interaction between two collinear cracks in a piezoelectric material plate under anti-plane shear
waves is investigated by using the non-local theory for impermeable crack surface conditions. By using the Fourier transform,
the problem can be solved with the help of two pairs of triple integral equations. These equations are solved using the Schmidt
method. This method is more reasonable and more appropriate. Unlike the classical elasticity solution, it is found that no
stress and electric displacement singularity is present at the crack tip. The non-local dynamic elastic solutions yield a
finite hoop stress at the crack tip, thus allowing for a fracture criterion based on the maximum dynamic stress hypothesis.
The project supported by the Natural Science Foundation of Heilongjiang Province and the National Natural Science Foundation
of China(10172030, 50232030) 相似文献
17.
A class of singularly perturbed reaction diffusion systems 总被引:4,自引:0,他引:4
莫嘉琪 《应用数学和力学(英文版)》1997,18(3):273-277
A class of singularly perturbed reaction diffusion systems are considered. Under suitable conditions, using the comparison
theorem the asymptotic behavior of solution for the initial boundary value problems is studied.
Project supported by the National Natural Science Foundation of China 相似文献
18.
The stress rate integral equations of elastoplaticity are deduced based on Ref. [1] by consistent methods. The point at which
the stresses and/or displacements are calculated can be in the body or on the boundary, and in the plastic region or elastic
one. The existence of the principal value integral in the plastic region is demonstrated strictly, and the theoretical basis
is presented for the paticular solution method by unit initial stress fields. In the present method, programming is easy and
general, and the numerical results are excellent.
The project supported by the National Natural Science Foundation of China 相似文献
19.
Appling Mindlin's theory of thick plates and Hamilton system to propagation of elastic waves under free boundary condition, a solution of the problem was given. Dispersion equations of propagation mode of strip plates were deduced from eigenfunction expansion method. It was compared with the dispersion relation that was gained through solution of thick plate theory proposed by Mindlin. Based on the two kinds of theories, the dispersion curves show great difference in the region of short waves, and the cutoff frequencies are higher in Hamiltonian systems. However, the dispersion curves are almost the same in the region of long waves. 相似文献
20.
HAMILTONIAN SYSTEM AND SIMPLETIC GEOMETRY IN MECHANICS OF COMPOSITE MATERIALS(Ⅰ)——FUNDAMENTAL THEORY
For the first time, Hamiltonian system used in dynamics is introduced to formulate statics and Hamiltonian equation is derived
corresponding to the original governing equation, which enables separation of variables to work and eigen function to be obtained
for the boundary problem. Consequently, analytical and semi-analytical solutions can be got. The method is especially suitable
to solve rectangular plane problem and spatial prism in elastic mechanics.
The paper presents a new idea to solve partially differential equation in solid mechanics. The flexural problem and plane
stress problem of laminated plate are studied in detail.
This project is supported by National Natural Science Foundation of China for Post-Doctorate Research. 相似文献