P. Raghavan¹, S. Ghosh²

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.2, pp. 151-170, 2004, DOI:10.3970/cmes.2004.005.151

Abstract This paper presents an adaptive multi-level computational model that combines a conventional displacement based finite element model with a microstructural Voronoi cell finite element model for multi-scale analysis of composite structures with non-uniform microstructural heterogeneities as obtained from optical or scanning electron micrographs. Three levels of hierarchy, with different resolutions, are introduced in this model to overcome shortcomings posed by modeling and discretization errors. Among the three levels are: (a) level-0 of pure macroscopic analysis; (b) level-1 of macro-micro coupled modeling, used for signaling the switch over from macroscopic analyses to pure microscopic analyses; and More >

Spandan Maiti¹, Philippe H. Geubelle¹

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.2, pp. 91-102, 2004, DOI:10.3970/cmes.2004.005.091

Abstract The dynamic propagation and branching of a mode I crack in polycrystalline brittle materials like ceramics are investigated numerically using a 2-D explicit grain-based cohesive/volumetric finite element scheme. The granular microstructure of the ceramics is taken into account and the crack is restricted to propagate along the grain boundaries. Special emphasis is placed on studying the effect of grain size and cohesive parameters on the crack branching instability. More >

Peter W. Chung¹, Raju R. Namburu², Brian J. Henz³

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.1, pp. 45-62, 2004, DOI:10.3970/cmes.2004.005.045

Abstract A method is developed based on an additive modification to the first Lagrangian elasticity tensor to make the finite element method for hyperelasticity viable at the atomic length scale in the context of lattice statics. Through the definition of an overlap region, the close-ranged atomic interaction energies are consistently summed over the boundary of each finite element. These energies are subsequently used to additively modify the conventional material property tensor that comes from the second derivative of the stored energy function. The summation over element boundaries, as opposed to atom clusters, allows the mesh and More >

N. Chandra¹ and C. Shet

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.1, pp. 21-34, 2004, DOI:10.3970/cmes.2004.005.021

Abstract Cohesive Zone Models (CZMs)\ are increasingly being used to simulate fracture and fragmentation processes in metallic, polymeric, ceramic materials and composites thereof. Instead of an infinitely sharp crack envisaged in linear elastic fracture mechanics, CZM assumes the presence of a fracture process zone where the energy is transferred from external work both in the forward and the wake regions of the propagating crack. In this paper, some of the mechanistic and computational issues in the application of CZM \ to model failure and fracture in real materials are discussed. In specific we address the issue More >

S. Ghosh ¹

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.1, pp. 1-4, 2004, DOI:10.3970/cmes.2004.005.001

Abstract This article has no abstract. More >

Jin Fa Lee¹, Robert Lee², Fernando Teixeira³

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.5, pp. 423-434, 2004, DOI:10.3970/cmes.2004.005.423

Abstract This paper presents the application of a p-type Multiplicative Schwarz Method (pMUS) for solving three dimensional waveguide discontinuity with arbitrary shapes. The major ingredients of current approach are: a hierarchical curl-conforming basis functions that incorporates an in-exact Helmholtz decomposition; and, treating each polynomial space (or basis functions group) as an abstract grid/domain in the Schwarz method. Various numerical examples are studied using the proposed approach. The performance has been compared to currently available commercial software and demonstrated superior performance in terms of accuracy as well as efficiency. 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 >

F. Auricchio¹, L. Petrini², R. Pietrabissa³, E. Sacco⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.3&4, pp. 365-380, 2003, DOI:10.3970/cmes.2003.004.365

Abstract Since 80’s many devices were developed to exploit the unique blend of mechanical and biocompatibility properties of shape memory alloys in orthodontic applications. It results in a high clinical effectiveness, but also in a spreading of technical knowledge on the properties of the single appliances. The goal of the present contribution is to contrast this sense of bewilderness and to prepare the basis for a simulationtool able to support the orthodontist choice. In particular a finite-element beam with a one-dimensional constitutive law, able to describe the SMA super elasticity and shape memory effect, is presented: More >

I. J. Rao¹, J.D. Humphrey², K.R. Rajagopal³

CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.3&4, pp. 439-456, 2003, DOI:10.3970/cmes.2003.004.439

Abstract Recent discoveries in molecular and cell biology reveal that many cell types sense and respond (via altered gene expression) to changes in their mechanical environment. Such mechanotransduction mechanisms are responsible for many changes in structure and function, including the growth and remodeling process. To understand better, and ultimately to use (e.g., in tissue engineering), biological growth and remodeling, there is a need for mathematical models that have predictive and not just descriptive capability. In contrast to prior models based on reaction-diffusion equations or the concept of volumetric growth, we examine here a newly proposed constrained More >

K.J. Fischer^1,2, J.A. Bastidas³, H.J. Pfaeffle², J.D. Towers²

CMES-Computer Modeling in Engineering & Sciences, Vol.4, No.3&4, pp. 397-404, 2003, DOI:10.3970/cmes.2003.004.397

Abstract The two bones of the forearm, the radius and the ulna, have been shown to bear different proportions of the overall forearm load at the wrist and the elbow. This biomechanical data suggests load transfer between the bones occurs through the soft tissues of the forearm. Load transfer from radius to ulna through passive soft tissues such as the interosseous ligament (IOL) has been experimentally measured. Ex vivo studies of the forearm, however, cannot account for the effect of internal loads generated by the muscles and, in some cases, external forces acting directly on the… More >