M.C. Ho Ba Tho¹

CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.3&4, pp. 489-496, 2003, DOI:10.3970/cmes.2003.004.489

Abstract The objective of the paper is to address the methodology developed to model bone and joints with individualised geometric and material properties from medical image data. An atlas of mechanical properties of human bone has been investigated demonstrating individual differences. From these data, predictive relationships have been established between mechanical properties and quantitative data derived from measurements on medical images. Subsequently, geometric and numerical models of bones with individualised geometrical and mechanical properties have been developed from the same source of image data. The advantages of this modelling technique are its ability to study the More >

Amitesh Maiti¹

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.5, pp. 589-600, 2002, DOI:10.3970/cmes.2002.003.589

Abstract Atomistic modeling and simulations are becoming increasingly important in the design of new devices at the nanoscale. In particular, theoretical modeling of carbon nanotubes have provided useful insight and guidance to many experimental efforts. To this end, we report simulation results on the electronic, structural and transport properties for two different applications of carbon nanotube-based devices: (1) effect of adsorbates on field emission; and (2) effect of mechanical deformation on the electronic transport. The reported simulations are based on First Principles Density Functional Theory (DFT), classical molecular mechanics, and tight-binding transport based on the recursive More >

K. Garikipati¹

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.2, pp. 175-184, 2002, DOI:10.3970/cmes.2002.003.175

Abstract The embedding of micromechanical models in the macromechanical formulation of continuum solid mechanics can be treated by a variational multiscale method. A scale separation is introduced on the displacement field into coarse and fine scale components. The fine scale displacement is governed by the desired micromechanical model. Working within the variational framework, the fine scale displacement field is eliminated by expressing it in terms of the coarse scale displacement and the remaining fields in the problem. The resulting macromechanical formulation is posed solely in terms of the coarse scale displacements, but is influenced by the More >

Z. Zhong¹, Y. Dai^1,2, C. C. Mei³, P. Tong^1,4

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.1, pp. 77-86, 2002, DOI:10.3970/cmes.2002.003.077

Abstract In this paper we reexamine the sheet-flow model proposed by Fung and Sobin (1969) for blood flow in capillaries in the pulmonary alveoli from micromechanical point of view. The pulmonary alveolar capillary is assumed to be two parallel membranes connected by periodic tissue posts. Blood is spread out into the very thin layer or sheet between the two membranes. The pulmonary alveolar sheet thus has a microstructure of hexagonal cells. A two-scale theory of homogenization is used to establish the canonical equations for the unit cell. The microscale solution is obtained by means of finite… More >

P. H. Wen¹, M. H. Aliabadi¹, A. Young²

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.1, pp. 1-10, 2002, DOI:10.3970/cmes.2002.003.001

Abstract In this paper, applications of the boundary element method to damaged and undamaged aircraft curved panels with mechanical repairs are presented. The effects of fastened repairs are replaced by uniform distribution forces in the area of cross-section of the rivet and can be determined from the compatibility condition of displacements. A coupled boundary integral formulation of a shear deformable plate and two dimensional plane stress elasticity is used to determine the bending and membrane forces on the rivets. Domain integrals in each integral equation are determined using the dual reciprocity method. The stress intensity factors More >

Selden B. Crary¹, Peter Cousseau², David Armstrong¹, David M. Woodcock³, Eva H. Mok¹, Olivier Dubochet⁴, Philippe Lerch⁴, Philippe Renaud²

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 127-140, 2000, DOI:10.3970/cmes.2000.001.127

Abstract We present a new and unique software capability for finding statistical optimal designs of deterministic experiments on continuous cuboidal regions. The objective function for the design optimization is the minimization of the expected integrated mean squared error of prediction of the metamodel that will be found, subsequent to the running of the computer simulations, using the best linear unbiased predictor (BLUP). The assumed response-model function includes an unknown, stochastic term, Z. We prove that this criterion, which we name I_Z-optimality, is equivalent to I-optimality for non-deterministic experiments, in the limit of zero correlations among the Z's for More >

Wenjing Ye¹, Subrata Mukherjee²

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 111-120, 2000, DOI:10.3970/cmes.2000.001.111

Abstract Polynomial driving-force comb drives are designed using numerical simulation. The electrode shapes are obtained using the indirect boundary element method. Variable gap comb drives that produce combinations of linear, quadratic, and cubic driving-force profiles are synthesized. This inverse problem is solved by an optimization procedure. Sensitivity analysis is carried out by the direct differentiation approach (DDA) in order to compute design sensitivity coefficients (DSCs) of force profiles with respect to parameters that define the shapes of the fingers of a comb drive. The DSCs are then used to drive iterative optimization procedures. Designs of variable More >

S. Taschini¹, J. Müller², A. Greiner², M. Emmenegger¹, H. Baltes¹, J.G. Korvink²

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 31-44, 2000, DOI:10.3970/cmes.2000.001.031

Abstract We present three techniques to accurately model the thermomechanical response of microsystem components: a new, accurate and stable Kirchhoff-Love multi-layered plate model implemented as an Argyris finite element, a model for the amplitude fluctuations of vibrational modes in micro-mechanical structures within a gaseous environment, and the consistent refinement of a finite element mesh in order to maximize the computational accuracy for a given mesh size. We have implemented these techniques in our in-house MEMS finite element program and accompanying Monte Carlo simulator. We demonstrate our approach to dynamic modeling by computing the thermomechanical response of More >