E. Ferretti¹

CMES-Computer Modeling in Engineering & Sciences, Vol.9, No.1, pp. 19-48, 2005, DOI:10.3970/cmes.2005.009.019

Abstract In this study nonlocality is discussed with regard to the differential and discrete formulations. Here, nonlocality is found to be a concept attaining not to the description of the material, but to the governing equations. This has made it possible to discuss the opportunity of introducing nonlocality in the constitutive equations, in order to give respectability to strain-softening damage models. When using the differential formulation, a length scale must be introduced into the material description of a strain-softening modeling, particularly when the size-effect is involved. In the opinion of the Author, this need lies in… More >

Igor Karšaj¹, Carlo Sansour², Jurica Sorić¹

CMES-Computer Modeling in Engineering & Sciences, Vol.8, No.1, pp. 45-60, 2005, DOI:10.3970/cmes.2005.008.045

Abstract In this paper, a free energy-based formulation incorporating the effect of kinematic hardening is proposed. The formulation is able to reproduce symmetric expressions for the back stress while incorporating the multiplicative decomposition of the deformation gradient. Kinematic hardening is combined with isotropic hardening where an associative flow rule and von Mises yield criterion are applied. An accurate and trivial wise objective integration algorithm employing the exponential map is developed. In order to ensure a high convergence rate in the global iteration approach, an algorithmic tangent operator is derived. The computational algorithm is implemented and applied More >

S. Deguchi^1,2, T. Ohashi², M. Sato²

Molecular & Cellular Biomechanics, Vol.2, No.3, pp. 125-134, 2005, DOI:10.3970/mcb.2005.002.125

Abstract Actin bundles in vascular endothelial cells (ECs) play a critical role in transmitting intracellular forces between separate focal adhesion sites. However, quantitative descriptions of tension level in single actin bundles in a physiological condition are still poorly studied. Here, we evaluated magnitude of preexisting tension in a single actin bundle of ECs on the basis of measurements of its preexisting stretching strain and tensile properties. Cultured ECs expressing fluorescently-labeled actin were treated with detergents to extract acin bundles. One end of an actin bundle was then dislodged from the substrate by using a microneedle, resulting… More >

B. Amaziane¹, A. Naji², D. Ouazar³, A. H.-D. Cheng⁴

CMC-Computers, Materials & Continua, Vol.2, No.2, pp. 85-96, 2005, DOI:10.3970/cmc.2005.002.085

Abstract In this paper the optimization of groundwater pumping in coastal aquifers under the threat of saltwater intrusion is investigated. The aquifer is inhomogeneous and contains several hydraulic conductivities zones. The aquifer data such as the hydraulic conductivities are uncertain, but with their expected mean and standard deviation values given. A stochastic boundary element method based on the perturbation technique is employed as the simulation tool. The stochastic optimization is handled by the chance-constrained programming. Genetic algorithm is selected as the optimization tool. Numerical examples of deterministic and stochastic problems are provided to demonstrate the feasibility More >

Michihiko Nakagaki¹, Shuji Takashima², Ryosuke Matsumoto¹, Noriyuki Miyazaki²

CMES-Computer Modeling in Engineering & Sciences, Vol.10, No.3, pp. 199-208, 2005, DOI:10.3970/cmes.2005.010.199

Abstract The present paper focuses on the micromechanical phenomena occurring in the polycrystalline metal materials. Correlations between the material hardening and the plastic lattice dislocation were discussed with the presence of the grain boundary. The characteristic distribution of the plastic strain gradient is numerically recognized, and hence the validity of incorporating the strain gradient term in the constitutive law is demonstrated. Also, the modeling of the inclusion interface sliding and debonding was performed on the equivalent inclusion theory to develop the constitutive law for the composite. The sliding model is considered to be effective to model More >

A. Cazzani¹, E. Garusi², A. Tralli³, S.N. Atluri⁴

CMC-Computers, Materials & Continua, Vol.2, No.1, pp. 23-38, 2005, DOI:10.3970/cmc.2005.002.023

Abstract Fibre-reinforced plates and shells are finding an increasing interest in engineering applications. Consequently, efficient and robust computational tools are required for the analysis of such structural models. As a matter of fact, a large amount of laminate finite elements have been developed and incorporated in most commercial codes for structural analysis. \newline In this paper a new laminate hybrid assumed-strain plate element is derived within the framework of the First-order Shear Deformation Theory (i.e. assuming that particles of the plate originally lying along a straight line which is normal to the undeformed middle surface remain… More >

A. Shukla^1,1, A.R. Dunn^2,2, M.A. Moses^3,3, K.J. Van Vliet^4,4

Molecular & Cellular Biomechanics, Vol.1, No.4, pp. 279-290, 2004, DOI:10.3970/mcb.2004.001.279

Abstract Although it is established that endothelial cells can respond to external mechanical cues (e.g., alignment in the direction of fluid shear stress), the extent to which mechanical stress and strain applied via the endothelial cell substrate impact biomolecular and cellular processes is not well-understood. This issue is particularly important in the context of inflammation, vascular remodeling, and cancer progression, as each of these processes occurs concurrently with localized increases in strain and marked changes in molecules secreted by adjacent cells. Here, we systematically vary the level and duration of cyclic tensile strain applied to human… More >

E. Pan¹, X. Jiang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.1, pp. 77-90, 2004, DOI:10.3970/cmes.2004.006.077

Abstract It is of great importance to understand the factors that contribute to the strain and electrical distributions, which are induced by the misfit strain between a buried quantum wire (QWR) and its surrounding matrix. One of the important factors is the shape or geometry of cross section of the QWR. Utilizing a recent exact closed-form solution [Pan (2004)], we study the model system of QWRs with different shapes and calculate both the surface and internal elastic and piezoelectric fields induced by QWRs embedded in semiconductor GaAs substrates by properly setting the size and location of More >

J. H. Kim¹, Y. H. Kim ¹, S. W. Lee²

CMC-Computers, Materials & Continua, Vol.1, No.2, pp. 141-152, 2004, DOI:10.3970/cmc.2004.001.141

Abstract A simple triangular solid shell element formulation is developed for efficient analysis of plates and shells undergoing finite rotations. The kinematics of the present solid shell element formulation is purely vectorial with only three translational degrees of freedom per node. Accordingly, the kinematics of deformation is free of the limitation of small angle increments, and thus the formulation allows large load increments in the analysis of finite rotation. An assumed strain field is carefully selected to alleviate the locking effect without triggering undesirable spurious kinematic modes. In addition, the curved surface of shell structures is More >

V.K. Tewary², D.T. Read²

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.4, pp. 359-372, 2004, DOI:10.3970/cmes.2004.006.359

Abstract An integrated Green's function and molecular dynamics technique is developed for multiscale modeling of a nanostructure in a semi-infinite crystal lattice. The equilibrium configuration of the atoms inside and around the nanostructure is calculated by using molecular dynamics that accounts for nonlinear interatomic forces. The molecular dynamics is coupled with the lattice statics Green's function for a large crystallite containing a million or more atoms. This gives a fully atomistic description of a nanostructure in a large crystallite that includes the effect of nonlinear forces. The lattice statics Green's function is then related to the… More >