Jin-Ho Roh¹, In Lee²

CMES-Computer Modeling in Engineering & Sciences, Vol.26, No.1, pp. 13-30, 2008, DOI:10.3970/cmes.2008.026.013

Abstract A methodology to maintain the configuration of inflated membrane structures using shape memory alloy (SMA) film actuator is numerically investigated. The two- dimensional incremental formulation of the SMA constitutive model is developed. New parameters related to the thermodynamic energy equation are introduced to describe more general behaviors of the SMA film. With numerical algorithm of wrinkling and SMAs, the interactions between the inflated membrane structure and the SMA film are investigated by using a finite element program. The effectiveness of SMA film to control the configuration of an inflated membrane structure is examined. To demonstrate More >

Tienfuan Kerh^1,2, J.S. Lai¹, D. Gunaratnam², R. Saunders²

CMES-Computer Modeling in Engineering & Sciences, Vol.26, No.1, pp. 1-12, 2008, DOI:10.3970/cmes.2008.026.001

Abstract Taiwan frequently suffers from strong ground motion, and the current building code is essentially based on two seismic zones, A and B. The design value of horizontal acceleration for zone A is 0.33g, and the value for zone B is 0.23g. To check the suitability of these values, a series of actual earthquake records are considered for evaluating peak ground acceleration (PGA) for each of the zones by using neural network models. The input parameters are magnitude, epicenter distance, and focal depth for each of the checking stations, and the peak ground acceleration is calculated… More >

G. Kosec¹, B. Šarler¹

CMES-Computer Modeling in Engineering & Sciences, Vol.25, No.3, pp. 197-208, 2008, DOI:10.3970/cmes.2008.025.197

Abstract This paper explores the application of the mesh-free Local Radial Basis Function Collocation Method (LRBFCM) in solution of coupled heat transfer and fluid flow problems in Darcy porous media. The involved temperature, velocity and pressure fields are represented on overlapping sub-domains through collocation by using multiquadrics Radial Basis Functions (RBF). The involved first and second derivatives of the fields are calculated from the respective derivatives of the RBF's. The energy and momentum equations are solved through explicit time stepping. The pressure-velocity coupling is calculated iteratively, with pressure correction, predicted from the local continuity equation violation.… More >

L.K. Keppas¹, G.I. Giannopoulos¹, N.K. Anifantis¹

CMES-Computer Modeling in Engineering & Sciences, Vol.25, No.3, pp. 181-196, 2008, DOI:10.3970/cmes.2008.025.181

Abstract In the present paper a boundary element procedure is formulated to treat two-dimensional time dependent thermo-elastic contact problems incorporating thermal resistance along the contacting surfaces. The existence of pressure-dependent thermal contact leads to coupling of temperature and stress fields. Therefore, the inherent non-linearity of the problem demands simultaneous treating of both thermal and mechanical boundary integral equations while iterative procedures are introduced to ensure equilibrium of mechanical and thermal contact conditions at each step of the process. The transient behavior of interfacial cracks in bimaterial solids when undergo thermal shock in the presence of partial More >

A. Sellier¹

CMES-Computer Modeling in Engineering & Sciences, Vol.25, No.3, pp. 165-180, 2008, DOI:10.3970/cmes.2008.025.165

Abstract The slow viscous and either imposed or gravity-driven migration of a solid arbitrarily-shaped particle suspended in a Newtonian liquid bounded by a spherical cavity is calculated using two different boundary element approaches. Each advocated method appeals to a few boundary-integral equations and, by contrast with previous works, also holds for non-spherical particles. The first procedure puts usual free-space Stokeslets on both the cavity and particle surfaces whilst the second one solely spreads specific Stokeslets obtained elsewhere in Oseen (1927) on the particle's boundary. Each approach receives a numerical implementation which is found to be in More >

Wenzhong Tang¹, Suresh G. Advani¹

CMES-Computer Modeling in Engineering & Sciences, Vol.25, No.3, pp. 149-164, 2008, DOI:10.3970/cmes.2008.025.149

Abstract In this paper, a method for studying nanotube dynamics in simple shear flow was developed. A nanotube was described as a flexible fiber with a sphere-chain model. The forces on the nanotube were obtained by molecular dynamics simulations. The motion of the nanotube in simple shear flow was tracked by the flexible fiber dynamics method [Tang and Advani (2005)]. The viscosity of dilute nanotube suspensions was calculated based on the nanotube dynamics, and the effects of the aspect ratio and initial curvature of the nanotube on suspension viscosity are explored and discussed. More >

C. Moulinec¹, R. Issa², J.-C. Marongiu³, D. Violeau⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.25, No.3, pp. 133-148, 2008, DOI:10.3970/cmes.2008.025.133

Abstract The gridless Smoothed Particle Hydrodynamics (SPH) numerical method is preferably used in Computational Fluid Dynamics (CFD) to simulate complex flows with one or several convoluted free surfaces. This type of flows requires distorted meshes with classical Eulerian mesh-based methods or very fine meshes with Volume of Fluid method. Few 3-D SPH simulations have been carried out to our knowlegde so far, mainly due to prohibitive computational investment since the number of particles required in 3-D is usually too large to be handled by a single processor. In this paper, a parallel 3-D SPH code is More >

Atsuya Oishi¹, Shinobu Yoshimura²

CMES-Computer Modeling in Engineering & Sciences, Vol.25, No.2, pp. 115-132, 2008, DOI:10.3970/cmes.2008.025.115

Abstract This paper describes the finite element analyses of dynamic problems using graphics hardware. The graphics hardware, known as GPU that is an acronym of Graphics Processing Unit, was first developed only for processing 3D computer graphics. However it has obtained both flexible programmability using a high-level shader programming language such as OpenGL Shading Language (GLSL), and has also obtained fast numerical processing ability of over 160 GFLOPS that is much faster than CPU. In this paper, GPU is utilized for the finite element analyses of dynamic problems. Two different computational tasks in the dynamic finite More >

Y.Y. Shan¹, C. Shu^1,2, Z.L. Lu³

CMES-Computer Modeling in Engineering & Sciences, Vol.25, No.2, pp. 99-114, 2008, DOI:10.3970/cmes.2008.025.099

Abstract The local multiquadric-based differential quadrature (MQ-DQ) method proposed by [Shu, Ding, and Yeo (2003)] is a natural mesh-free approach for derivative approximation, which is easy to be implemented to solve problems with curved boundary. Previously, it has been well tested for the two-dimensional (2D) case. In this work, this mesh-free method was extended to simulate fluid flow problems with curved boundary in three-dimensional (3D) space. The main concern of this work is to numerically study the performance of the 3D local MQ-DQ method and demonstrate its capability and flexibility for simulation of 3D incompressible fluid More >

J.R. Jimenez-Octavio¹, O. Lopez-Garcia², E. Pilo¹, A. Carnicero²

CMES-Computer Modeling in Engineering & Sciences, Vol.25, No.2, pp. 81-98, 2008, DOI:10.3970/cmes.2008.025.081

Abstract This paper presents a multidisciplinary design and optimization method of power transmission lines. This optimization method solves both mechanical and electrical problems by a new strongly coupled method that also optimizes the potential designs using a genetic algorithm. A multi-objective function is formulated to simplify a constrained typical optimization problem into an unconstrained one. The scope of this work is the sizing and configuration optimization problem with fixed topology. The method is applied to a railway overhead transmission line. The genetic algorithm is applied to mechanical, electrical and electromechanical optimization problems obtaining good results. Finally, More >