L. Gao¹, K. Liu^1,2, Y. Liu³

CMES-Computer Modeling in Engineering & Sciences, Vol.12, No.3, pp. 181-196, 2006, DOI:10.3970/cmes.2006.012.181

Abstract A new numerical algorithm based on the Meshless Local Petrov-Galerkin approach is presented for analyzing the dynamic fracture problems in elastic media. To simplify the treatment of essential boundary condition, a novel modified Moving Least Square (MLS) procedure is proposed by introducing Lagrange multiplier into MLS procedure, which can perform both MLS approximation and interpolation in one approximation domain. The compact spline function is used as the test function in the local form of elasto-dynamic equations. For the feature of stress wave propagation, the coupled second-order ODEs respect to the time are solved by the… More >

S. Yoshimura ¹

CMES-Computer Modeling in Engineering & Sciences, Vol.11, No.1, pp. 17-26, 2006, DOI:10.3970/cmes.2006.011.017

Abstract This paper describes a development of an advanced traffic simulator based on a multi-agent approach which is named MATES (Multi-Agent based Traffic and Environment Simulator). City traffic phenomena are essentially regarded as complex systems consisting of a number of human beings. Each element creating traffic phenomena such as car (driver), traffic signal, pedestrian and others is modeled as an intelligent agent that possesses its own logic of behavior and preference. The environment surrounding each agent consists of other cars, road network, traffic signals, pedestrian and others. Interaction among numerous agents simulates nonlinear behaviors of city More >

S. Straface¹, S. Troisi, V. Gagliardi

CMC-Computers, Materials & Continua, Vol.3, No.3, pp. 155-166, 2006, DOI:10.3970/cmc.2006.003.155

Abstract The present work shows an alternative to the classical methods to solve the Richards' Equation (RE), used to model flow in unsaturated porous media. This alternative is named Cell Method (CM). The CM is based on a preliminary reformulation of the mathematical model in a partially discrete form, which preserves as much as possible the physical and geometrical content of the original problem, and is made possible by the existence and properties of a common mathematical structure of field theories. The goal is to maintain the focus, both in the modelling and discretization steps, on… More >

Hamid Sharifi¹ and Augustin Gakwaya¹

CMC-Computers, Materials & Continua, Vol.3, No.2, pp. 77-96, 2006, DOI:10.3970/cmc.2006.003.077

Abstract In this paper, an object-oriented modeling of solid material constitutive behavior using the UML notation is presented. Material properties are first classified into large and small deformation kinematical models. In the small deformation package, we keep classes such as Elastic, ElastoPlastic, ViscoElastic and ViscoPlastic. In the large deformation package, we store classes such as ElastoPlastic, HyperElastic, HyperPlastic, HyperViscoElastic, HyperViscoPlastic and so on. The hierarchical structure, the association relationships as well as key attributes and methods of these classes are presented. We used a C++ implementation of the above model for developing HyperElastic, HyperElastoPlastic and Contact More >

CHEN FENG*, CHEN XIANG-MING**, CHEN ZHI*, JIANG HAN-LIANG*, PAN XIAO-PING*, HU ZHONG-RONG*, LIU RONG-HUA*, CHEN XIAO-MING*

BIOCELL, Vol.29, No.3, pp. 253-259, 2005, DOI:10.32604/biocell.2005.29.253

Abstract We want to construct a yeast expression system for thymosin α1 (Tα1) to make the orally administered Tα1 preparation possible. The whole Tα1 DNA fragment was obtained by PCR. After being digested with restriction enzymes, it was cloned into pYES2 vector. Sequencing was performed to identify the recombinant. The sequence of Tα1 in recombinant coincided with the original one reported in Genbank. When pYES2-Tα1 plasmid was transformed into yeast, galactose instead of glucose was used to induce Tα1 expression. Western blot was performed to identify the quality of the expressed Tα1. Dried yeast containing pYEST2-Tα1… More >

S. N. Atluri¹

Structural Durability & Health Monitoring, Vol.1, No.1, pp. 1-20, 2005, DOI:10.3970/sdhm.2005.001.001

Abstract The solution of three-dimensional cracks (arbitrary surfaces of discontinuity) in solids and structures is considered. The BEM, developed based on the symmetric Galerkin BIEs, is used for obtaining the fracture solutions at the arbitrary crack-front. The finite element method is used to model the uncracked global (built-up) structure for obtaining the stresses in an otherwise uncracked body. The solution for the cracked structural component is obtained in an iteration procedure, which alternates between FEM solution for the uncracked body, and the SGBEM solution for the crack in the local finite-sized subdomain. In addition, some crack… More >

Chein-Shan Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.3, pp. 231-258, 2005, DOI:10.3970/cmes.2005.008.231

Abstract Using a group-theoretical approach in the Minkowski space we explore kinematic hardening rules from a viewpoint of the Poincaré group. The resultant models possess two intrinsic times q₀^a and q₀^b; the first q₀^a controls the on/off switch of plasticity, and the second q₀^b controls the pace of back stress during plastic deformation. We find that some existent kinematic hardening rules, including the modifications from the Armstrong-Frederick kinematic hardening rule, can be categorized into type I, type II and type III, which correspond respectively to q₀^b = 0, q₀^b = q₀^a and q₀^b ≠ q₀^a. Based More >

V. Sladek¹, J. Sladek¹, M. Tanaka²

CMES-Computer Modeling in Engineering & Sciences, Vol.7, No.1, pp. 69-84, 2005, DOI:10.3970/cmes.2005.007.069

Abstract An efficient numerical method is proposed for 2-d potential problems in anisotropic media with continuously variable material coefficients. The method is based on the local integral equations (utilizing a fundamental solution) and meshfree approximation of field variable. A lot of numerical experiments are carried out in order to study the numerical stability, accuracy, convergence and efficiency of several approaches utilizing various interpolations. More >

Yaxin Song¹, D. Michael McFarland¹, Lawrence A. Bergman¹, Alexander F. Vakakis²

CMES-Computer Modeling in Engineering & Sciences, Vol.10, No.2, pp. 153-170, 2005, DOI:10.3970/cmes.2005.010.153

Abstract A general interface element is developed for dynamic response analysis of structures with jointed interfaces, which can account for damping due to both impact and friction. Contact effects are included through a segment-to-segment contact model which considers the stick-slip-slap behavior at every point along the joint interface. A nonlinear friction law is adopted at the interface to describe microscopic relative motion due to the deformation of the asperities on the interface. Numerical examples demonstrate that the general joint interface element is capable of accounting for both friction and impact damping in jointed interfaces, as well More >

Zhenyu Xue¹, Ashkan Vaziri¹, John W. Hutchinson¹

CMES-Computer Modeling in Engineering & Sciences, Vol.10, No.1, pp. 79-96, 2005, DOI:10.3970/cmes.2005.010.079

Abstract A constitutive model for the elastic-plastic behavior of plastically compressible orthotropic materials is proposed based on an ellipsoidal yield surface with evolving ellipticity to accommodate non-uniform hardening or softening associated with stressing in different directions. The model incorporates rate-dependence arising from material rate-dependence and micro-inertial effects. The basic inputs are the stress-strain responses under the six fundamental stress histories in the orthotropic axes. Special limits of the model include classical isotropic hardening theory, the Hill model for incompressible orthotropic solids, and the Deshpande-Fleck model for highly porous isotropic foam metals. A primary motivation is application… More >