E.J. Sapountzakis¹, A.E. Kampitsis²

CMES-Computer Modeling in Engineering & Sciences, Vol.87, No.2, pp. 97-126, 2012, DOI:10.3970/cmes.2012.087.097

Abstract In this paper a Boundary Element Method (BEM) is developed for the inelastic analysis of beams of arbitrarily shaped constant cross section having at least one axis of symmetry, resting on nonlinear inelastic foundation. The beam is subjected to arbitrarily distributed or concentrated vertical cyclic loading along its length, while its edges are subjected to the most general boundary conditions. A displacement based formulation is developed and inelastic redistribution is modelled through a distributed plasticity model exploiting material constitutive laws and numerical integration over the cross sections. An incremental - iterative solution strategy is adopted to resolve both the plastic… More >

V. Mallardo¹, M.H. Aliabadi²

CMES-Computer Modeling in Engineering & Sciences, Vol.87, No.2, pp. 77-96, 2012, DOI:10.3970/cmes.2012.087.077

Abstract The present paper intends to couple the Fast Multipole Method (FMM) with the Boundary Element Method (BEM) in the 2D scalar wave propagation. The procedure is aimed at speeding the computation of the integrals involved in the governing Boundary Integral Equations (BIEs) on the basis of the distance between source point and integration element. There are three main contributions. First, the approach is of adaptive type in order to reduce the number of floating-point operations. Second, most integrals are evaluated analytically: the diagonal and off-diagonal terms of the H and G matrices by consolidated techniques, whereas the moment Mk by… More >

Kentaro Doi^1,2, Ikumi Onishi¹, Satoyuki Kawano^1,3

CMES-Computer Modeling in Engineering & Sciences, Vol.77, No.2, pp. 113-136, 2011, DOI:10.3970/cmes.2011.077.113

Abstract Hydrogen technologies are currently one of the most actively researched topics. A lot of researches have tied to enhance their energy conversion efficiencies. In the present study, numerical analyses have been carried out focusing on hydrogen-storage carbon materials which are expected to realize high gravimetric and volumetric capacities. In particular, dissociative adsorption processes of H₂ molecules above graphene surfaces have been investigated by ab initio molecular dynamics. The present results indicate that a steric graphene surface plays an important role in enhancing the charge transfer which induces dissociation of H₂ and adsorption of H atoms on the surface. The dissociation… More >

W. A. El-Askary^1,2, S. A. Wilson², A. Hegab²

CMES-Computer Modeling in Engineering & Sciences, Vol.76, No.3&4, pp. 235-266, 2011, DOI:10.3970/cmes.2011.076.235

Abstract In the present work, a complete simulation of reactive flow in the combustion chamber of a rocket motor equipped with convergent-divergent nozzle has been introduced. The model describes the combustion process inside the combustion chamber considering a steady premixed reactant gas injected through side porous walls of the combustion chamber. The products flow through a convergent-divergent nozzle with adiabatic impermeable walls. The reactants are treated as two-dimensional, multi-components, turbulent compressible flow. The local properties of the mixture are calculated and updated during the solution process. At the boundary of the combustion chamber, a constant mass flux and predefined properties are… More >

B.Y. Tian¹, B. Tie¹, D. Aubry¹, X.Y. Su²

CMES-Computer Modeling in Engineering & Sciences, Vol.76, No.3&4, pp. 217-234, 2011, DOI:10.3970/cmes.2011.076.217

Abstract The present work is devoted to a theoretical analysis and numerical modeling of elastic wave propagation firstly in a one-dimensional periodic elastic rod structure and then in two-dimensional periodic elastic beam structures by using Bloch wave theorem. The dispersion relation between Bloch wave vectors and eigen frequencies is obtained and its dependency upon the micro-structural characteristics of the periodic cellular structure is analyzed. Thanks to the Bloch wave transforms, only the primitive cell is considered theoretically or numerically and the phenomena of frequency band-gaps and the diffracted waves caused by the periodic cells are modeled and analyzed. More >

Şahin Emrah Amrahov¹, Iman N. Askerzade¹

CMES-Computer Modeling in Engineering & Sciences, Vol.76, No.3&4, pp. 207-216, 2011, DOI:10.3970/cmes.2011.076.207

Abstract We consider a fuzzy linear system with crisp coefficient matrix and with an arbitrary fuzzy number in parametric form on the right-hand side. It is known that the well-known existence and uniqueness theorem of a strong fuzzy solution is equivalent to the following: The coefficient matrix is the product of a permutation matrix and a diagonal matrix. This means that this theorem can be applicable only for a special form of linear systems, namely, only when the system consists of equations, each of which has exactly one variable. We prove an existence and uniqueness theorem, which can be use on… More >

Yun Chen¹, Junzhi Cui², Yufeng Nie¹, Yiqiang Li¹

CMES-Computer Modeling in Engineering & Sciences, Vol.76, No.3&4, pp. 189-206, 2011, DOI:10.3970/cmes.2011.076.189

Abstract This paper presents a new numerical algorithm for thermal-mechanical coupled analysis of polycrystalline aggregates based on the plastic slip theory inside crystals and the frictional contact on their interfaces. It involves the mechanics and heat conduction behaviors caused by both force loads and temperature changing within crystal and contact interfaces between crystals. Firstly, the constitutive relationship inside single crystal, and the moment equations and energy equations are derived by means of rate-dependent plastic deformation theory and the formulation of elastic-plastic tangent modulus depended on temperature. Secondly, the contact conditions with friction, including frictional heat generation and heat transfer across the… More >

Qin Lou¹, Zhaoli Guo^1,2, Chuguang Zheng¹

CMES-Computer Modeling in Engineering & Sciences, Vol.76, No.3&4, pp. 175-188, 2011, DOI:10.3970/cmes.2011.076.175

Abstract Due to the mesoscopic and kinetic nature, the lattice Boltzmann equation (LBE) method has become an efficient and powerful tool for modeling and simulating interfacial dynamics of multi-phase flows. In this work we discuss several fundamental properties of two-phase LBE models. Particularly, the effects of force discretization, spurious currents in the vicinity of interfaces, and checkerboard effects with the underlying lattices, are investigated. More >

J. A. Ferreira¹, P. de Oliveira², P. M. da Silva³

CMES-Computer Modeling in Engineering & Sciences, Vol.76, No.3&4, pp. 163-174, 2011, DOI:10.3970/cmes.2011.076.163

Abstract In two previous papers the authors presented mathematical models that simulate the mass of drug delivered, in vitro Ferreira, Oliveira, Silva, Carreira, Gil and Murta (2010) and in vivo Ferreira, Oliveira, Silva and Murta (2011), from a therapeutic contact lens. In the present paper the time it takes to reach an equilibrium state is studied. A closed formula based on the concept of effective time is derived and the influence of the parameters of the model is analyzed. More >

Ziya Aktas¹, Semih Cetin²

CMES-Computer Modeling in Engineering & Sciences, Vol.76, No.2, pp. 133-162, 2011, DOI:10.3970/cmes.2011.076.133

Abstract The knowledge society has been developed and shaped by amazing improvements during the last two decades. On that development and improvement, social sciences such as psychology or anthropology have also had significant impact as much as real sciences like medicine or engineering, in particular, Information Technology or Information and Communications Technology. The new trends and explosion of knowledge due to Internet and Web technologies have radically changed the way we structure business and its main building block, i.e. "knowledge". Though information/knowledge system development efforts have been regarded formerly as mere information technology activities, now we have been experiencing alternative ways… More >