F. J. Bellomo¹, S. Oller², F. Armero³, L. G. Nallim¹

CMES-Computer Modeling in Engineering & Sciences, Vol.80, No.1, pp. 1-22, 2011, DOI:10.3970/cmes.2011.080.001

Abstract Some of the key factors that regulate growth and remodeling of tissues are fundamentally mechanical. However, it is important to take into account the role of biological availability to generate new tissue together with the stresses and strains in the processes of natural or pathological growth. In this sense, the model presented in this work is oriented to describe growth of vascular tissue under "stress driven growth" considering biological availability of the organism. The general theoretical framework is given by a kinematic formulation in large strain combined with the thermodynamic basis of open systems. The… More >

W.L. Yang¹, Y.F. Nie², Y.T. Wu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.79, No.3&4, pp. 261-270, 2011, DOI:10.3970/cmes.2011.079.261

Abstract Up to now, some methods have been proposed to impose essential boundary conditions (EBCs) in meshless methods to solve partial differential equations system. Based on the theory analysis about moving least square (MLS) approximation and numerical experimentation results, a very simple method to impose EBCs in element-free Galerkin methods, which is the same easy as in finite element methods, is posed here. Compared with Lagrange multiplier method, the new method is simple and gives better results at the distributed nodes. The new method dues to a view point, different from normal understanding, that taking generalized More >

Durgesh Vikram¹, Sanjay Mittal², Partha Chakroborty¹

CMES-Computer Modeling in Engineering & Sciences, Vol.79, No.3&4, pp. 237-260, 2011, DOI:10.3970/cmes.2011.079.237

Abstract A stabilized finite element formulation is presented to solve the governing equations for traffic flow. The flow is assumed to be one-dimensional. Both, PW-type (Payne-Whitham) 2-equation models and the LWR-type (Lighthill-Whitham-Richards) 1-equation models are considered. The SUPG (Streamline-Upwind/Petrov-Galerkin) and shock capturing stabilizations are utilized. These stabilizations are sufficient for the 1-equation models. However, an additional stabilization is necessary for the 2-equation models. For the first time, such a stabilization is proposed. It arises from the coupling between the two equations and is termed as IEPG (Inter-Equation/Petrov-Galerkin) stabilization. Two behavioral models are studied: Greenshields' (GS) and Greenberg's… More >

N. Mai-Duy¹, T. Tran-Cong¹, N. Phan-Thien²

CMES-Computer Modeling in Engineering & Sciences, Vol.79, No.3&4, pp. 223-236, 2011, DOI:10.3970/cmes.2011.079.223

Abstract This paper presents a new numerical technique for solving the evolution equations in molecular dynamics (MD). The variation of the MD system is represented by radial-basis-function (RBF) equations which are constructed using integrated multiquadric basis functions and point collocation. The proposed technique requires the evaluation of forces once per time step. Several examples are given to demonstrate the attractiveness of the present implementation. 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… More >

I. Pérez¹, R. Roselló¹, C. Recarey¹, M. Cerrolaza²

CMES-Computer Modeling in Engineering & Sciences, Vol.79, No.3&4, pp. 183-200, 2011, DOI:10.3970/cmes.2011.079.183

Abstract Modeling the geometry and behavior of human bones is of the most concern when dealing with bone remodelling (external and internal) and poroelastic analysis. Complex geometries are frequently found in the human skeleton as well as orthotropic behavior of bone tissue. Spongy bone has a completely different constitution as compared with compact bone, which adds another relevant consideration if we want to get reliable results in biomechanical analysis. The modeling of both compact and spongy human-bone tissue is carried out by using packaging-particle methods. The methods generate circles (2D domains) and spheres (3D domains) in 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 More >

Lianhua Ma¹, Bernard F. Rolfe², Qingsheng Yang^1,3, Chunhui Yang^2,3

CMES-Computer Modeling in Engineering & Sciences, Vol.79, No.2, pp. 131-158, 2011, DOI:10.3970/cmes.2011.079.131

Abstract For fluid-filled closed cell composites widely distributed in nature, the configuration evolution and effective elastic properties are investigated using a micromechanical model and a multiscale homogenization theory, in which the effect of initial fluid pressure is considered. Based on the configuration evolution of the composite, we present a novel micromechanics model to examine the interactions between the initial fluid pressure and the macroscopic elasticity of the material. In this model, the initial fluid pressure of the closed cells and the corresponding configuration can be produced by applying an eigenstrain at the introduced fictitious stress-free configuration,… More >

C. A. Bustamante¹, W. F. Florez¹, H. Power², M. Giraldo¹, A. F. Hill¹

CMES-Computer Modeling in Engineering & Sciences, Vol.79, No.2, pp. 103-130, 2011, DOI:10.3970/cmes.2011.079.103

Abstract The two-dimensional Navier Stokes system of equations for incompressible flows is solved in the velocity vorticity formulation by means of the Control Volume-Radial Basis Function (CV-RBF) method. This method is an improvement to the Control Volume Method (CVM) based on the use of Radial Basis Function (RBF) Hermite interpolation instead of the classical polynomial functions. The main advantages of the CV-RBF method are the approximation order, the meshless nature of the interpolation scheme and the presence of the PDE operator in the interpolation. Besides, the vorticity boundary values are computed in terms of the values More >

Yoshihiro OCHIAI¹

CMES-Computer Modeling in Engineering & Sciences, Vol.79, No.2, pp. 83-102, 2011, DOI:10.3970/cmes.2011.079.083

Abstract In general, internal cells are required to solve unsteady thermo-elasto -plastic problems using a conventional boundary element method (BEM). However, in this case, the merit of BEM, which is the easy preparation of data, is lost. The conventional multiple-reciprocity boundary element method (MRBEM) cannot be used to solve thermo-elastoplastic problems, because the distribution of initial stress cannot be determined analytically. In this paper, it is shown that two-dimensional unsteady thermo-elastoplastic problems can be solved without the use of internal cells by using the triple-reciprocity BEM and a thin plate spline. The initial stress formulation is More >