Li Shan, Ning Cui, Ming Cheng, Kaixin Liu

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.4, pp. 353-384, 2012, DOI:10.3970/cmes.2012.083.353

Abstract In the present paper, a combined scheme of discrete element method (DEM) and meshless method for numerical simulation of impact problems is proposed. Based on the basic principle of continuum mechanics, an axisymmetric DEM framework is established for modeling the elastoplastic behavior of solid materials. Failure criteria are introduced to model the transformation from a continuum to a discontinuum. The friction force between contact elements is also considered after the failure appears. So our scheme can calculate not only the behavior of continuum and discontinuum, but also the transformation process from a continuum to a discontinuum. In addition, a meshless… More >

Kazuhiko Kakuda¹, Shunsuke Obara¹, Jun Toyotani¹, Mitsuhiko Meguro¹, Masakazu Furuichi¹

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.1, pp. 57-72, 2012, DOI:10.3970/cmes.2012.083.057

Abstract The application of a particle method to incompressible viscous fluid flow problem and its physics-based computer graphics are presented. The method is based on the MPS (Moving Particle Semi-implicit) scheme using logarithmic weighting function to stabilize the spurious oscillatory solutions for the pressure fields which are governed by Poisson equation. The physics-based computer graphics consist of the POV-Ray (Persistence of Vision Raytracer) rendering using marching cubes algorithm as polygonization. The standard MPS scheme is widely utilized as a particle strategy for the free surface flow, the problem of moving boundary, multi-physics/multi-scale ones, and so forth. Numerical results demonstrate the workability… More >

L. Novotný¹, M. Tsunori²

CMES-Computer Modeling in Engineering & Sciences, Vol.82, No.3&4, pp. 253-264, 2011, DOI:10.32604/cmes.2011.082.253

Abstract The welding simulation is carried out by an uncoupled thermal and mechanical analysis or by a coupled thermo-mechanical analysis. For weld-induced distortion and residual stress simulation, nonlinear mechanical analysis is required. Nonlinearities are caused by both nonlinear behaviour of the material and geometrical nonlinearity. Usually, the element birth technique is used to incorporate the filler material in the model. The ideal straight geometry may be altered by imperfections to enable buckling behaviour. Real component shapes contain various imperfections (e.g. geometrical, material). The finite element mesh may contain geometrical imperfections too. When a simple weld model is used, the mode of… More >

Qiang Li¹, Jie Ouyang¹, Guorong Wu¹, Xiaoyang Xu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.82, No.3&4, pp. 215-232, 2011, DOI:10.32604/cmes.2011.082.215

Abstract The governing equations of two-phase flows including gas and polymer melt are presented, which are solved using finite volume and domain extension methods with SIMPLEC technology. The melt filling and primary gas penetration in gas-assisted injection molding (GAIM) process are simulated, where the Cross-viscosity model is employed to describe the melt rheological behavior, and the CLSVOF(coupled Level Set and Volume of fluid) method is employed to capture the moving interfaces. In order to test and verify the coupled methods, melt filling in a rectangular plate with an insert is simulated, and the numerical results are in good agreement with those… More >

C.-D. Tran¹, D.-A. An-Vo¹, N. Mai-Duy¹, T. Tran-Cong¹

CMES-Computer Modeling in Engineering & Sciences, Vol.82, No.2, pp. 137-162, 2011, DOI:10.32604/cmes.2011.082.137

Abstract This paper presents a numerical approach for macro-micro multi-scale modelling of visco-elastic fluid flows based on the Integrated Radial Basis Function Networks (IRBFNs) and the Stochastic Simulation Technique (SST). The extra stress is calculated using the Brownian configuration fields (BCFs) technique while the velocity field is locally approximated at a set of collocation points using 1D-IRBFNs. In this approach, the stress is decoupled from the velocity field and computed from the molecular configuration directly without the need for a closed form rheological constitutive equation. The equations governing the macro flow field are discretised using a meshless collocation method where the… More >

Jorge Daniel Riera¹, Letícia Fleck Fadel Miguel², Ignacio Iturrioz³

CMES-Computer Modeling in Engineering & Sciences, Vol.82, No.2, pp. 113-136, 2011, DOI:10.32604/cmes.2011.082.113

Abstract In the truss-like Discrete Element Method (DEM), masses are considered lumped at nodal points and interconnected by means of uni-dimensional elements with arbitrary constitutive relations. In previous studies of the tensile fracture behavior of concrete cubic samples, it was verified that numerical predictions of fracture of non-homogeneous materials using DEM models are feasible and yield results that are consistent with the experimental evidence so far available. Applications that demand the use of large elements, in which extensive cracking within the elements of the model may be expected, require the consideration of the increase with size of the fractured area, in… More >

V.G. Yakhno¹, H.Çerdik Yaslan²

CMES-Computer Modeling in Engineering & Sciences, Vol.81, No.3&4, pp. 295-310, 2011, DOI:10.3970/cmes.2011.081.295

Abstract The time-dependent differential equations of elasticity for 3D quasicrystals are considered in the paper. These equations are written in the form of a vector partial differential equation of the second order with symmetric matrix coefficients. The Green's function is defined for this vector partial differential equation. A new method of the numerical computation of values of the Green's function is proposed. This method is based on the Fourier transformation and some matrix computations. Computational experiments confirm the robustness of our method for the computation of the time-dependent Green's function in icosahedral quasicrystals. More >

V.G.Yakhno¹, T.M. Yakhno²

CMES-Computer Modeling in Engineering & Sciences, Vol.80, No.3&4, pp. 233-250, 2011, DOI:10.3970/cmes.2011.080.233

Abstract The time-dependent Maxwell's equations in non-dispersive homogeneous bi-anisotropic materials are considered in the paper. These equations are written as a symmetric hyperbolic system. A new method of the computation of the electric and magnetic fields arising from electric current is suggested in the paper. This method consists of the following. The Maxwell's equations are written in terms of the Fourier transform with respect to the space variables. The Fourier image of the obtained system is a system of ordinary differential equations whose coefficients depend on the 3D Fourier parameter. The formula for the solution of the obtained system is derived… More >

K.S. Kim¹, B.H. Lee², M.H. Kim¹, J.C. Park³

CMES-Computer Modeling in Engineering & Sciences, Vol.79, No.3&4, pp. 201-222, 2011, DOI:10.3970/cmes.2011.079.201

Abstract The coupling and interactions between vessel motion and inner-tank sloshing are investigated by a potential-CFD (Computational Fluid Dynamics) hybrid method in time domain. Potential-theory-based 3D diffraction/radiation panel program is used to obtain the hydrodynamic coefficients and wave forces for the simulation of vessel motion in time domain. The liquid sloshing in tanks is simulated in time domain by using the improved Moving Particle Simulation (PNU-MPS) method and it is validated through comparison against sloshing experiments. The calculated sloshing tank forces and moments are applied to the vessel-motion simulation as excitation forces and moments. The updated ship motion, which is influenced… More >

M.A. Argenta¹, A.P. Gebert², E.S. Filho³, B.A. Felizari⁴, M.B. Hecke⁵

CMES-Computer Modeling in Engineering & Sciences, Vol.79, No.3&4, pp. 159-182, 2011, DOI:10.3970/cmes.2011.079.159

Abstract Various methods in the literature proposesequations to calculate the stiffness as a function of density of bone tissue such as apparent density and ash density among others[Helgason, Perilli, Schileo, Taddei, Brynjolfsson and Viceconti, 2008]. Other ones present a value of an equivalent elasticity modulus, obtained by statistical adjustments of curves generated through mechanical compression tests over various specimens[Chevalier, Pahr, Allmer, Charlebois and Zysset, 2007; Cuppone, Seedhom, Berry and Ostell, 2004]. Bone tissue is a material withdifferent behaviors according to the scale of observation. It has a complex composite hierarchical structure, which is responsible for assign optimal mechanical properties. Its characteristics,… More >