Yang Yang¹, Anil Misra²

CMES-Computer Modeling in Engineering & Sciences, Vol.64, No.1, pp. 1-36, 2010, DOI:10.3970/cmes.2010.064.001

Abstract Gradient theories have found wide applications in modeling of strain softening phenomena. This paper presents a higher order stress-strain theory to describe the damage behavior of strain softening materials. In contrast to most conventional gradient approaches for damage modeling, the present higher order theory considers strain gradients and their conjugate higher-order stress such that stable numerical solutions may be achieved. We have described the derivation of the required constitutive relationships, the governing equations and its weak form for this higher-order theory. The constitutive coefficients were obtained from a granular media approach such that the internal More >

Hideki Fujii¹, Shinobu Yoshimura¹, Kazuya Seki¹

CMES-Computer Modeling in Engineering & Sciences, Vol.63, No.3, pp. 265-282, 2010, DOI:10.3970/cmes.2010.063.265

Abstract Traffic system is a typical complex system emerged through interactions among a large number of traffic actors such as car drivers, pedestrians and others. We model each actor as an intelligent agent that can judge and act by itself autonomously, and develop a traffic simulator named MATES, which is based on an intelligent multi-agent model. In this simulator, microscopic behaviors of the traffic actors cause macroscopic traffic phenomena through their interaction. In this research, we newly develop a coordinative behavior model among multiple cars, and implement it to MATES to enhance the reproducibility of traffic More >

V. Sladek¹, J. Sladek¹, Ch. Zhang²

CMES-Computer Modeling in Engineering & Sciences, Vol.63, No.3, pp. 243-264, 2010, DOI:10.3970/cmes.2010.063.243

Abstract The paper deals with diminishing the prolongation of the computational time due to procedural evaluation of the shape functions and their derivatives in weak formulations implemented with meshless approximations. The proposed numerical techniques are applied to problems of stationary heat conduction in functionally graded media. Besides the investigation of the computational efficiency also the accuracy and convergence study are performed in numerical tests. More >

Kazuhiko Suga^1,2, Takahiko Ito¹

CMES-Computer Modeling in Engineering & Sciences, Vol.63, No.3, pp. 223-242, 2010, DOI:10.3970/cmes.2010.063.223

Abstract Flow passages in micro/nano-electro-mechanical systems (MEMS/ -NEMS) usually have complicated geometries. The present study thus discusses on the latest lattice Boltzmann methods (LBMs) for micro/nano fluidics to evaluate their applicability to micro/nano-flows in complex geometries. Since the flow regime is the continuum to the slip and transitional regime with a moderate Knudsen number (Kn), the LBMs presently focused on feature the wall boundary treatment and the relaxation-time for modeling such flow regimes. The discussed micro flow (µ-flow) LBMs are based on the Bhatnagar-Gross-Krook (BGK) model and the multiple relaxation-time (MRT) model. The presently chosen µ-flow… More >

Binxin Yang¹, Jie Ouyang¹, Tao Jiang¹, Chuntai Liu²

CMES-Computer Modeling in Engineering & Sciences, Vol.63, No.3, pp. 191-222, 2010, DOI:10.3970/cmes.2010.063.191

Abstract A gas-solid-liquid three-phase model is proposed for fiber reinforced composites mold filling process. The fluid flow is described in Eulerian coordinate while the dynamics of fibers is described in Langrangian coordinate. The interaction of fluid flow and fibers are enclosed in the model. The influence of fluid flow on fibers is described by the resultant forces imposed on fibers and the influence of fibers on fluid flow is described by the momentum exchange source term in the model. A finite volume method coupled with a level set method for viscoelastic-Newtonian fluid flow is used to More >

Yue-Ting Zhou¹, Xing Li², De-Hao Yu³, Kang Yong Lee^1,4

CMES-Computer Modeling in Engineering & Sciences, Vol.63, No.2, pp. 163-190, 2010, DOI:10.3970/cmes.2010.063.163

Abstract In this paper, a coupled crack/contact model is established for the composite material with arbitrary periodic cracks indented by periodic punches. The contact of crack faces is considered. Frictional forces are modeled to arise between the punch foundation and the composite material boundary. Kolosov-Muskhelisvili complex potentials with Hilbert kernels are constructed, which satisfy the continuity conditions of stress and displacement along the interface identically. The considered problem is reduced to a system of singular integral equations of first and second kind with Hilbert kernels. Bounded functions are defined so that singular integral equations of Hilbert More >

Y. Inoue¹, R. Kobayashi¹, S. Ogata¹, T. Gotoh¹

CMES-Computer Modeling in Engineering & Sciences, Vol.63, No.2, pp. 137-162, 2010, DOI:10.3970/cmes.2010.063.137

Abstract Vibration of a single graphene and a pair of graphenes at micro meter scale induced by air flow is numerically simulated and examined by using a hybrid computational method starting from a microscopic level of description for the graphene. In order to bridge a huge gap in spatial and time scales in their motions, the carbon atoms of the graphene are represented by a small number of coarse grained particles, the fluid motion is described by the lattice Boltzmann equation and the momentum exchange at the boundary is treated by the time averaged immersed boundary… More >

A.N.M. Imroz Choudhury¹, Michael D. Steffen¹, James E. Guilkey², Steven G.Parker³

CMES-Computer Modeling in Engineering & Sciences, Vol.63, No.2, pp. 117-136, 2010, DOI:10.3970/cmes.2010.063.117

Abstract We present a physically based method for visualizing deformation in particle simulations, such as those describing structural mechanics simulations. The method uses the deformation gradient tensor to transform carefully chosen glyphs representing each particle. The visualization approximates how simulated objects responding to applied forces might look in reality, allowing for a better understanding of material deformation, an important indicator of, for example, material failure. It can also help highlight possible errors and numerical deficiencies in the simulation itself, suggesting how simulations might be changed to yield more accurate results. More >

J.H. Tian^1,2, X. Han², S.Y. Long², G.Y. Sun², Y. Cao¹, G.Q. Xie³

CMES-Computer Modeling in Engineering & Sciences, Vol.63, No.2, pp. 101-116, 2010, DOI:10.3970/cmes.2010.063.101

Abstract A transient heat conduction analysis of the functionally graded material (FGM) plates has been investigated based on the hybrid numerical method (HNM). HNM combines the layer element method with the method of Fourier transforms and proves to be efficient and reliable. The FGM plates are infinite large and the material properties vary continuously through thickness. The transient heat source acted on the FGM plates. The temperature distribution of the FGM plates is obtained in different time and different position. Some useful results for transient heat conduction are shown in figures. Applications of HNM to transient More >

Alex Ferguson¹, Matthew R. Smith², J.-S. Wu³

CMES-Computer Modeling in Engineering & Sciences, Vol.63, No.1, pp. 79-100, 2010, DOI:10.3970/cmes.2010.063.079

Abstract A novel approach for the use of multiple continuous uniform distributions for reconstruction of the Maxwell-Boltzmann equilibrium probability distribution function is used for the solution of one and two dimensional Euler equations. The Uniform distribution Equilibrium Flux Method (UEFM) is a kinetic-theory based flux solver which calculates true directional, volume to volume fluxes based on integration (over velocity space and physical space) of a sum of uniform probability distribution functions working to approximate the equilibrium distribution function. The resulting flux expressions contain only the Heaviside unit step function and do not require the evaluation of More >