B.B. Karki¹, R. Kumar¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.3, No.1, pp. 35-42, 2007, DOI:10.3970/icces.2007.003.035

Abstract We report important preliminary results from atomistic simulations of grain boundaries in minerals. The recently developed parallel PCMD (polycrystal molec-ular dynamics) program was used to perform structural optimization. In particular, we have simulated the {310}/[001] symmetric tilt grain boundary of MgO as a function of pressure. The simulation cell containing about 55,000 atoms was used. Visualization of the atomic position-time series data show that the structure changes dramatically on compression from a simple open-structure at zero pressure to a highly dense structure containing high coordination state and a screw-like dislocation at high pressure, consistent with More >

S.P. Xiao¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.3, No.1, pp. 15-20, 2007, DOI:10.3970/icces.2007.003.015

Abstract A bridging domain method for coupling continuum models with molecular models is described. In this method, the continuum and molecular domains are overlapped in a bridging subdomain, where the Hamiltonian is taken to be a linear combination of the continuum and molecular Hamiltonians. We enforce the compatibility in the bridging domain by Lagrange multipliers or by the augmented Lagrangian method. An explicit algorithm for dynamic solutions is developed. In this paper, the bridging domain multiscale method is employed to study nanotube-based composites. More >

M-A Lavoie¹, A. Gakwaya¹, M. Nejad Ensan², D.G. Zimcik²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.2, No.4, pp. 111-118, 2007, DOI:10.3970/icces.2007.002.111

Abstract This paper reviews numerical methods that are currently available to simulate bird strike as well as the theory of the event. It also summarizes important parameters and provides guidelines as to how to set up the analysis and how to evaluate a model. The information provided is based on physical properties and available results regarding a bird and its behaviour upon impact. The simulations have been performed with LS-DYNA 970 but can be done in similar dynamic finite elements analysis codes. More >

T. Uehara¹, M. Fukui², N. Ohno³

The International Conference on Computational & Experimental Engineering and Sciences, Vol.2, No.3, pp. 61-66, 2007, DOI:10.3970/icces.2007.002.061

Abstract Stress evolution during grain growth in microstructure formation process are simulated by using the phase field model. Fundamental equations accounting for the coupling effects among phase transformation, temperature and stress/strain have been formulated based on thermodynamical laws, in which thermal expansion, transformation dilatation, and stress dependency on phase transformation are considered. An elasto-plastic constitutive relationship is applied so as to obtain the residual stresses. Based on these equations, numerical simulations are carried out by the finite element method. Results for two kinds of initial arrangement of nuclei are demonstrated in this paper. One model has More >

J. París¹, M. Casteleiro¹, F. Navarrina¹, I. Colominas¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.2, No.1, pp. 13-20, 2007, DOI:10.3970/icces.2007.002.013

Abstract Topology structural optimization problems have been usually stated in terms of a maximum stiffness (minimum compliance) approach. In this kind of formulations, the aim is to distribute a given amount of material in a certain domain, so that the stiffness of the resulting structure is maximized for a given load case. In addition, no stress or displacement constraints are taken into account. This paper presents a different strategy: a minimum weight Finite Element formulation for optimization of continuum structures subjected to stress constraints. We propose two different approaches to take into account the stress constraints More >

Nishioka T.¹, Fujita N.¹, Fujimoto T.¹, Kogame M.¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.1, No.3, pp. 127-132, 2007, DOI:10.3970/icces.2007.001.127

Abstract In this study, numerical simulations of mixed-mode fracture paths in dynamic fracture phenomenon are carried out by using moving finite element method based on Delaunay automatic mesh generation. In addition, the experiments under same condition was carried out, and the both results were compared. The calculated paths by the simulation agree well with the fracture paths of the experiments. More >

Nishioka T.¹, sugami M.¹, Fujimoto T.¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.1, No.3, pp. 119-126, 2007, DOI:10.3970/icces.2007.001.119

Abstract In this paper, the simulations of fatigue crack propagation and dynamic fracture path prediction are carried out for specimens containing circular holes or inclusions, using the moving finite element method based on Delaunay automatic triangulation. And, we compared the numerical results with the experimental results. More >

Guanbin Song^∗,†,‡, Yang Ju^∗,†,§, Hitoshi Soyama^*, Toshiro Ohashi^¶, Masaaki Sato^¶

Molecular & Cellular Biomechanics, Vol.4, No.4, pp. 201-210, 2007, DOI:10.3970/mcb.2007.004.201

Abstract Mechanical stimulation is critical to both physiological and pathological states of living cells. Although a great deal of research has been done on biological and biochemical regulation of the behavior of bone marrow mesenchymal stem cells (MSCs), the influence of biomechanical factors on their behavior is still not fully documented. In this study, we investigated the modulation of mechanical stretch magnitude, frequency, and duration on the human marrow mesenchymal stem cells (hMSCs) proliferation by an in vitro model system using a mechanical stretch loading apparatus, and optimized the stretch regime for the proliferation of hMSCs.… More >

Nooshin Haghighipour^∗, Mohammad Tafazzoli-Shadpour^∗, Mohammad Ali Shokrgozar^†, Samira Amini^∗, Amir Amanzadeh^†, Mohammad Taghi Khorasani^‡

Molecular & Cellular Biomechanics, Vol.4, No.4, pp. 189-200, 2007, DOI:10.3970/mcb.2007.004.189

Abstract Evaluation of mechanical environment on cellular function is a major field of study in cellular engineering. Endothelial cells lining the entire vascular lumen are subjected to pulsatile blood pressure and flow. Mechanical stresses caused by such forces determine function of arteries and their remodeling. Critical values of mechanical stresses contribute to endothelial damage, plaque formation and atherosclerosis. A device to impose cyclic strain on cultured cells inside an incubator was designed and manufactured operating with different load amplitudes, frequencies, numbers of cycles and ratios of extension to relaxation. Endothelial cells cultured on collagen coated silicon… More >

Donald F. Ward Jr.^*, William A. Williams^*, Nicole E. Schapiro^*, Samuel R. Christy^*, Genevieve L. Weber^*, Megan Salt, Robert F. Klees^*, Adele Boskey^†, George E. Plopper ^∗,‡

Molecular & Cellular Biomechanics, Vol.4, No.4, pp. 177-188, 2007, DOI:10.3970/mcb.2007.004.177

Abstract Focal adhesion kinase (FAK) is a key integrator of integrin-mediated signals from the extracellular matrix to the cytoskeleton and downstream signaling molecules. FAK is activated by phosphorylation at specific tyrosine residues, which then stimulate downstream signaling including the ERK1/2 pathway, leading to a variety of cellular responses. In this study, we examined the effects of FAK point mutations at tyrosine residues (Y397, Y925, Y861, and Y576/7) on osteogenic differentiation of human mesenchymal stem cells exposed to collagen I and cyclic tensile strain. Our results demonstrate that FAK signaling emanating from Y397, Y925, and to a More >