Ying Liu¹, Yufeng Nie², Weiwei Zhang², Lei Wang²

CMES-Computer Modeling in Engineering & Sciences, Vol.55, No.1, pp. 89-110, 2010, DOI:10.3970/cmes.2010.055.089

Abstract In the light of the ideas and treatment technologies about molecular dynamics simulation and bubble meshing, a new approach of node placement for the meshless method called node placement method by bubble simulation (NPBS method), is proposed. Nodes are seen as the centers of the bubbles which can be moved by their interacting forces. Through dynamic simulation, bubbles are placed into a near-optimal configuration, and the centers of bubbles will form a good-quality node distribution in the domain. This process doesn't need updating the mesh connection constantly, i.e., is totally meshfree. Some example results show that the uniform point sets… More >

Z. T. Ma¹, X. Zhang^1,2, P. Huang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.55, No.1, pp. 61-88, 2010, DOI:10.3970/cmes.2010.055.061

Abstract The Material Point Method (MPM) is more expensive in terms of storage than other methods, as MPM makes use of both mesh and particle data. Therefore, it is critical to develop an efficient MPM framework for engineering applications, such as impact and explosive simulations. This paper presents a new architecture for MPM computer code, developed using object-oriented design, which enables MPM analysis of a mass of grains, large deformation, high strain rates and complex material behavior. It is flexible, extendible, and easily modified for a variety of MPM analysis procedures. An MPM scheme combining contact algorithm with USF, USL and… More >

Z. Y. Yan^1,2, J. Zhang¹, W. Ye¹, T.X. Yu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.55, No.1, pp. 33-60, 2010, DOI:10.3970/cmes.2010.055.033

Abstract An 3-D precorrected-FFT accelerated BEM approach for the linear elastic analysis of porous solids with randomly distributed pores of arbitrary shape and size is described in this paper. Both the upper bound and the lower bound of elastic properties of solids with spherical pores are obtained using the developed fast BEM code. Effects of porosity and pore shape on the elastic properties are investigated. The performance of several theoretical models is evaluated by comparing the theoretical predictions with the numerical results. It is found that for porous solids with spherical pores, the performances of the generalized self-consistent method and Mori-Tanaka… More >

Surkay D. Akbarov^1,2,3, Mugan S. Guliev⁴, Ramazan Tekercioglu⁵

CMES-Computer Modeling in Engineering & Sciences, Vol.55, No.1, pp. 1-32, 2010, DOI:10.3970/cmes.2010.055.001

Abstract Dispersion relations of axisymmetric longitudinal wave propagation in a finite pre-strained compound (bi-material) cylinder made from high elastic incompressible materials are investigated within the scope of a piecewise homogeneous body model utilizing three-dimensional linearized theory wave propagation in the initially stressed body. The materials of the inner and outer cylinders are assumed to be neo-Hookean. The numerical results regarding the influence of the initial strains in the inner and outer cylinders on the wave dispersion are presented and discussed. These results are obtained for the case where the material of the inner solid cylinder is stiffer than that of the… More >

Yongchang Cai^1,2, J.K. Paik³, Satya N. Atluri³

CMES-Computer Modeling in Engineering & Sciences, Vol.54, No.3, pp. 335-368, 2009, DOI:10.3970/cmes.2009.054.335

Abstract This paper presents a simple finite element method, based on assumed moments and rotations, for geometrically nonlinear large rotation analyses of space frames consisting of members of arbitrary cross-section. A von Karman type nonlinear theory of deformation is employed in the updated Lagrangian co-rotational reference frame of each beam element, to account for bending, stretching, and torsion of each element. The Reissner variational principle is used in the updated Lagrangian co-rotational reference frame, to derive an explicit expression for the (12x12)symmetrictangent stiffness matrix of the beam element in the co-rotational reference frame. The explicit expression for the finite rotation of… More >

M. Dumbser¹, D.S. Balsara²

CMES-Computer Modeling in Engineering & Sciences, Vol.54, No.3, pp. 301-334, 2009, DOI:10.3970/cmes.2009.054.301

Abstract In this article we use the new, unified framework of high order one-step P_NP_M schemes recently proposed for inviscid hyperbolic conservation laws by Dumbser, Balsara, Toro, and Munz (2008) in order to solve the viscous and resistive magnetohydrodynamics (MHD) equations in two and three space dimensions on unstructured triangular and tetrahedral meshes. The P_NP_M framework uses piecewise polynomials of degree N to represent data in each cell and piecewise polynomials of degree M ≥ N to compute the fluxes and source terms. This new general machinery contains usual high order finite volume schemes (N = 0) and discontinuous Galerkin finite… More >

Arif Amirov¹, Zekeriya Ustaoglu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.54, No.3, pp. 283-300, 2009, DOI:10.3970/cmes.2009.054.283

Abstract We present the solvability of a two space dimensional coefficient inverse problem for a transport-like equation and investigate the approximate solution of this problem with the use of centered difference formulas and a symbolic approximation method. Since this inverse problem is overdetermined, which is the main difficulty in studying of its solvability, it is replaced by a related determined one by using some extension of the class of unknown functions. More >

E. Ferretti¹

CMES-Computer Modeling in Engineering & Sciences, Vol.54, No.3, pp. 253-282, 2009, DOI:10.3970/cmes.2009.054.253

Abstract In this study, the problem of finding the complete trajectory of propagation and the limiting load in plates with internal straight cracks is extended to the non-linear field. In particular, results concerning concrete plates in bi-axial tensile loading are shown. The concrete constitutive law adopted for this purpose is monotonic non-decreasing, as following according to previous studies of the author on monotonic mono-axial loading. The analysis is performed in a discrete form, by means of the Cell Method (CM). The aim of this study is both to test the new concrete constitutive law in biaxial tensile load and to verify… More >

J. Sladek¹, V. Sladek¹, M. Wünsche², Ch. Zhang²

CMES-Computer Modeling in Engineering & Sciences, Vol.54, No.2, pp. 223-252, 2009, DOI:10.3970/cmes.2009.054.223

Abstract A meshless method based on the local Petrov-Galerkin approach is proposed, to solve the interface crack problem between two dissimilar anisotropic elastic solids. Both stationary and transient mechanical and thermal loads are considered for two-dimensional (2-D) problems in this paper. A Heaviside step function as the test functions is applied in the weak-form to derive local integral equations. Nodal points are spread on the analyzed domain, and each node is surrounded by a small circle for simplicity. The spatial variations of the displacements and temperature are approximated by the Moving Least-Squares (MLS) scheme. After performing the spatial integrations, one obtains… More >

Delfim Soares Jr.¹

CMES-Computer Modeling in Engineering & Sciences, Vol.54, No.2, pp. 201-222, 2009, DOI:10.3970/cmes.2009.054.201

Abstract In this work, meshless methods based on the local Petrov-Galerkin approach are employed for the time-domain analysis of interacting fluid and solid systems. For the spatial discretization of the acoustic fluid and elastodynamic solid sub-domains involved in the coupled analyses, MLPG formulations adopting Gaussian weight functions as test functions are considered, as well as the moving least square method is used to approximate the incognita fields. For time discretization, the Houbolt's method is adopted. The fluid-solid coupled analysis is accomplished by an iterative algorithm. In this iterative approach, each sub-domain of the global model is analysed independently (as an uncoupled… More >