共查询到8条相似文献,搜索用时 0 毫秒
1.
Donald P. Henry Prasanta K. Banerjee 《International journal for numerical methods in engineering》1988,26(9):2079-2096
New two- and three-dimensional boundary element formulations are developed for elastoplastic stress analysis. These new procedures differ from previous work in that volume integration is not required to incorporate the non-linear effects in the analysis. Instead, initial stess rates are introduced in the boundary element system via particular integrals. The present formulation is implemented in a general purpose, multi-region system, and examples are presented to demonstrate the accuracy and versatility of the method. 相似文献
2.
This study deals with the domain decomposition method and particular integrals for multi-region inelastic transient dynamic
analysis. The particular integral formulation for single-region inelastic transient dynamic analysis is obtained by eliminating
the acceleration volume integral and treating the initial stress term by volume cell. The Houbolt time integration scheme
is used for the time- marching process. The Newton-Raphson algorithm for plastic multiplier is used to solve the system equation.
In order to extend to multi-region problems, the domain decomposition method is examined. The domain of the original problem
is subdivided into subregions. The interface boundary conditions are updated by using the iterative coupling employing Schwarz
algorithm. Numerical results of two example problems are given to demonstrate the validity and accuracy of the present formulation. 相似文献
3.
G. Y. Yu 《Computational Mechanics》2002,29(3):191-198
This paper presents a symmetric collocation BEM (SCBEM)/FEM coupling procedure applicable to 2-D time domain structural–acoustic
interaction problems. The use of symmetry for BEM not only saves memory storage but also enables the employment of efficient
symmetric equation solvers, especially for BEM/FEM coupling procedure. Compared with symmetric Galerkin BEM (SGBEM) where
double boundary integration should be carried out, SCBEM can reduce significantly the computing cost. Two numerical examples
are included to illustrate the effectiveness and accuracy of the proposed method.
Received: 2 November 2001 / Accepted: 27 May 2002 相似文献
4.
F. C. Araújo W. J. Mansur L. K. Nishikava 《Engineering Analysis with Boundary Elements》1999,23(10):825-833
A time-marching process similar to the well-known Wilson θ-method is used in order to develop an algorithm for carrying out the 3D time domain analyses with the boundary element method (BEM). The scheme described here, when incorporated to existing BE algorithms, can improve substancially the stability of the tractions time responses for both: bounded and unbounded domain applications. In order to conclude in fact that the proposed time-marching scheme makes possible to broaden the choice of the time step length, the BE time domain response for a classical example is discussed. For this analysis linear time interpolation functions for displacements and tractions are employed. In addition, to the basic idea of the θ time-marching scheme presented here an analysis of stability by numerical experimentation and computational aspects of the time domain BEM algorithm are other topics discussed. 相似文献
5.
Like the finite element method (FEM), the symmetric Galerkin boundary element method (SGBEM) can produce symmetric system
matrices. While widely developed for two dimensional problems, the 3D-applications of the SGBEM are very rare. This paper
deals with the regularization of the singular integrals in the case of 3D elastostatic problems. It is shown that the integration
formulas can be extended to curved elements. In contrast to other techniques, the Kelvin fundamental solutions are used with
no need to introduce the new kernel functions. The accuracy of the developed integration formulas is verified on a problem
with known analytical solution.
Received 6 November 2000 相似文献
6.
This paper presents a rate-independent elastoplastic constitutive model for (nearly) incompressible biological fiber-reinforced
composite materials. The constitutive framework, based on multisurface plasticity, is suitable for describing the mechanical
behavior of biological fiber-reinforced composites in finite elastic and plastic strain domains. A key point of the constitutive
model is the use of slip systems, which determine the strongly anisotropic elastic and plastic behavior of biological fiber-reinforced
composites. The multiplicative decomposition of the deformation gradient into elastic and plastic parts allows the introduction
of an anisotropic Helmholtz free-energy function for determining the anisotropic response. We use the unconditionally stable
backward-Euler method to integrate the flow rule and employ the commonly used elastic predictor/plastic corrector concept
to update the plastic variables. This choice is expressed as an Eulerian vector update the Newton's type, which leads to a
numerically stable and efficient material model. By means of a representative numerical simulations the performance of the
proposed constitutive framework is investigated in detail.
Received: 12 December 2001 / Accepted: 14 June 2002
Financial support for this research was provided by the Austrian Science Foundation under START-Award Y74-TEC. This support
is gratefully acknowledged. 相似文献
7.
A general algorithm of the distance transformation type is presented in this paper for the accurate numerical evaluation
of nearly singular boundary integrals encountered in elasticity, which, next to the singular ones, has long been an issue
of major concern in computational mechanics with boundary element methods. The distance transformation is realized by making
use of the distance functions, defined in the local intrinsic coordinate systems, which plays the role of damping-out the
near singularity of integrands resulting from the very small distance between the source and the integration points. By taking
advantage of the divergence-free property of the integrals with the nearly hypersingular kernels in the 3D case, a technique
of geometric conversion over the auxiliary cone surfaces of the boundary element is designed, which is suitable also for the
numerical evaluation of the hypersingular boundary integrals. The effects of the distance transformations are studied and
compared numerically for different orders in the 2D case and in the different local systems in the 3D case using quadratic
boundary elements. It is shown that the proposed algorithm works very well, by using standard Gaussian quadrature formulae,
for both the 2D and 3D elastic problems.
Received: 20 November 2001 / Accepted: 4 June 2002
The work was supported by the Science Foundation of Shanghai Municipal Commission of Education. 相似文献
8.
This paper presents a variational multiscale residual-based stabilized finite element method for the incompressible Navier–Stokes
equations. Structure of the stabilization terms is derived based on the two level scale separation furnished by the variational
multiscale framework. A significant feature of the new method is that the fine scales are solved in a direct nonlinear fashion,
and a definition of the stabilization tensor τ is derived via the solution of the fine-scale problem. A computationally economic procedure is proposed to evaluate the advection
part of the stabilization tensor. The new method circumvents the Babuska–Brezzi (inf–sup) condition and yields a stable formulation
for high Reynolds number flows. A family of equal-order pressure-velocity elements comprising 4-and 10-node tetrahedral elements
and 8- and 27-node hexahedral elements is developed. Convergence rates are reported and accuracy properties of the method
are presented via the lid-driven cavity flow problem. 相似文献