J. C. Páscoa¹, A. C. Mendes¹, L. M. C. Gato², R. Elder³

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.6, pp. 537-546, 2004, DOI:10.3970/cmes.2004.006.537

Abstract The paper presents an aerodynamic design method for turbomachinery cascades of blades. The prescribed conditions are the aerodynamic blade load and the blade thickness distributions. An iterative procedure was implemented, based on the solution of the Euler equations, to seek the blade geometry that provides the specified design conditions. A central finite-volume explicit time-marching scheme is used to solve the Euler equations in two-dimensional flow. The numerical scheme uses an adaptive nonlinear artificial dissipation term based on the limiter theory. Starting with the results from the flow analysis through an initially guessed cascade geometry, the More >

De Xie¹, Anthony M. Waas^1,2, Khaled W. Shahwan³, Jessica A. Schroeder⁴, Raymond G. Boeman⁵

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.6, pp. 515-524, 2004, DOI:10.3970/cmes.2004.006.515

Abstract A numerical method based on the virtual crack closure technique (VCCT) [Rybicki and Kanninen (1977)] and in conjunction with the finite element (FE) method is presented to compute strain energy release rates for cracks that kink. The method partitions the strain energy release rate and provides an efficient means to compute values of the mode I (G_I) and mode II (G_II) energy release rate at the tip of a kinking crack. The solution procedure is shown to be computationally efficient and operationally simple, involving only the nodal forces and displacements near the crack tip. Example problems More >

S. N. Atluri¹, Z. D. Han¹, A. M. Rajendran²

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.6, pp. 491-514, 2004, DOI:10.3970/cmes.2004.006.491

Abstract The Meshless Finite Volume Method (MFVM) is developed for solving elasto-static problems, through a new Meshless Local Petrov-Galerkin (MLPG) ``Mixed'' approach. In this MLPG mixed approach, both the strains as well as displacements are interpolated, at randomly distributed points in the domain, through local meshless interpolation schemes such as the moving least squares(MLS) or radial basis functions(RBF). The nodal values of strains are expressed in terms of the independently interpolated nodal values of displacements, by simply enforcing the strain-displacement relationships directly by collocation at the nodal points. The MLPG local weak form is then written… More >

E. Ferretti ¹

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.5, pp. 453-476, 2004, DOI:10.3970/cmes.2004.006.453

Abstract The Cell Method (CM) code with automatic remeshing for crack propagation analysis [Ferretti (2003)] is here used for modeling the pullout test. Particular emphasis is given to the analysis in the Mohr-Coulomb plane, since previous numerical models were not decisive in describing failure mechanism in pullout tests. The interpretations of experimental and analytical studies vary widely, and none of the existing explanations offer a complete description of the progressive failure of the concrete medium [Yener (1994)]. Nor do most existing interpretations appear to be totally compatible with the experimental evidence. Analysis of the failure mechanism… More >

S. Callsen¹, O. von Estorff¹, O. Zaleski²

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.5, pp. 421-430, 2004, DOI:10.3970/cmes.2004.006.421

Abstract In standard boundary element formulations, singular integrals need to be solved as soon as the considered sources coincide with the collocation points at the boundary. Using a desingularized boundary element approach, the sources are distributed on a surface outside the acoustic domain which means that they are never located at the boundary. Consequently, all the resulting kernels are nonsingular which reduces the complexity of the numerical treatment of the boundary integral equations considerably. In the current contribution a desingularized formulation is given for both, the direct and the indirect boundary element method used to solve More >

Z. D. Han¹, S. N. Atluri¹

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.2, pp. 169-188, 2004, DOI:10.3970/cmes.2004.006.169

Abstract Three different truly Meshless Local Petrov-Galerkin (MLPG) methods are developed for solving 3D elasto-static problems. Using the general MLPG concept, these methods are derived through the local weak forms of the equilibrium equations, by using different test functions, namely, the Heaviside function, the Dirac delta function, and the fundamental solutions. The one with the use of the fundamental solutions is based on the local unsymmetric weak form (LUSWF), which is equivalent to the local boundary integral equations (LBIE) of the elasto-statics. Simple formulations are derived for the LBIEs in which only weakly-singular integrals are included More >

Z.Y. Qian¹, Z.D. Han¹, S.N. Atluri¹

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.1, pp. 115-122, 2004, DOI:10.3970/cmes.2004.006.115

Abstract This article has no abstract. More >

N. Mai-Duy¹, T. Tran-Cong²

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.1, pp. 59-76, 2004, DOI:10.3970/cmes.2004.006.059

Abstract This paper presents a new domain decomposition technique based on the use of Boundary Integral Equations (BIEs) for the analysis of viscous flow problems. The domain of interest is divided into a number of non-overlapping subdomains and an iterative procedure is then employed to update the boundary conditions at interfaces. The new feature in the present work is that at each iteration, the relevant two subdomains, together containing a particular interface, are assumed to satisfy the governing BI equations which they do at the end of a convergent iterative process. Hence the boundary conditions on More >

Ch,ra S. Yerramalli¹, Anthony M. Waas²

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.1, pp. 1-16, 2004, DOI:10.3970/cmes.2004.006.001

Abstract Results from a 3D finite element based study of the compression response of unidirectional fiber reinforced polymer matrix composites (FRPC) are presented in this paper. The micromechanics based study was used to simulate the compressive response of glass and carbon fiber reinforced polymer matrix composites, with a view to understanding the effect of fiber diameter on compression strength. Results from the modeling and simulation indicate the presence of a complex three dimensional stress state in the matrix of the FRPC. Results from the simulation highlight the role of fiber diameter on the compressive response of More >

Wan-Sul Lee, Kie-Chan Kwon, Bong-Kyu Kim, Ji-Hyon Cho, Sung-Kie Youn¹

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.3, pp. 279-286, 2004, DOI:10.3970/cmes.2004.005.279

Abstract A numerical approach for eigenvalue analysis of the electrostatically tunable micro-mechanical actuators is presented. An efficient algorithm for calculating the natural frequency shifting in the micro-mechanical actuators due to applied DC turning voltage is proposed. In the calculations of the coupled field problem, the three-dimensional FEM/BEM approaches and iterative staggered algorithm are employed. The numerical examples for actually fabricated actuators are presented and the numerical analysis results are compared with experimental data. More >