John D. Clayton^1,*

CMES-Computer Modeling in Engineering & Sciences, Vol.120, No.2, pp. 333-350, 2019, DOI:10.32604/cmes.2019.06342

Abstract A theory invoking concepts from differential geometry of generalized Finsler space in conjunction with diffuse interface modeling is described and implemented in finite element (FE) simulations of dual-phase polycrystalline ceramic microstructures. Order parameters accounting for fracture and other structural transformations, notably partial dislocation slip, twinning, or phase changes, are dimensionless entries of an internal state vector of generalized pseudo-Finsler space. Ceramics investigated in computations are a boron carbide-titanium diboride (B₄C-TiB₂) composite and a diamond-silicon carbide (C-SiC) composite. Deformation mechanisms-in addition to elasticity and cleavage fracture in grains of any phase-include restricted dislocation glide (TiB₂ phase), deformation twinning (B₄C and β-SiC… More >

J.B. Alford¹, D.C. Simkins¹, R.A. Rembert¹, L. Hoyte, MD²

CMES-Computer Modeling in Engineering & Sciences, Vol.98, No.2, pp. 129-149, 2014, DOI:10.3970/cmes.2014.098.129

Abstract Mechanical deformation of tissues in the female pelvic floor is believed to be central to understanding a number of important aspects of women’s health, particularly pelvic floor dysfunction. A 2008 study of US women reported the prevalence of pelvic floor disorders in the 20 and 39 years range as 9.7% with the prevalence increasing with age until it reaches roughly 50% in the 80 and older age group [Nygaard, Barber, Burgio, and et al (2008)]. Clinical observation indicates a strong correlation between problems such as pelvic organ prolapse/urinary incontinence and vaginal childbirth. It is thought that childbirth parameters like fetal… More >

S,erson L. Gonzaga de Oliveira¹, Jéssica Renata Nogueira¹, João Manuel R. S. Tavares²

CMES-Computer Modeling in Engineering & Sciences, Vol.100, No.1, pp. 31-57, 2014, DOI:10.3970/cmes.2014.100.031

Abstract Triangulations and tetrahedrizations are important geometrical discretization procedures applied to several areas, such as the reconstruction of surfaces and data visualization. Delaunay and Voronoi tessellations are discretization structures of domains with desirable geometrical properties. In this work, a systematic review of algorithms with linear-time behaviour to generate 2D/3D Delaunay and/or Voronoi tessellations is presented. More >

Wen-Hwa Chen^2,3, Ming-Hsiao Lee⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.93, No.2, pp. 149-166, 2013, DOI:10.3970/cmes.2013.093.149

Abstract A novel meshless analysis procedure is established for practical implementation in dealing with three-dimensional structures with complicated geometry. By this procedure, to describe the surface of structure, the Stereo-lithography (STL) geometry technique is first adopted. Nodes are then generated and paved uniformly in the space over the entire structure analyzed. To decide the node distribution inside the structure, a geometry-related treatment scheme with relevant checking mechanisms is developed. Besides, a simple and direct spatial integration scheme is also proposed. By this integration scheme, integration points are evenly distributed in the structure and can be adjusted easily to meet the required… More >

Cheng-Hung Huang¹, Chi-An Chen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.36, No.1, pp. 1-22, 2008, DOI:10.3970/cmes.2008.036.001

Abstract A three-dimensional shape identification problem (or inverse geometry problem) in estimating the unknown irregular shape of internal cavity by using the steepest descent method (SDM) and a general purpose commercial code CFD-RC is examined in this study based on the simulated measured temperature distributions on the outer surface by infrared thermography. The advantage of calling CFD-RC as a subroutine in the present shape identification problem lies in its characteristics of easily-handling the problem considered here since the auto mesh function of CFD-RC enables the handling of this moving boundary problem. \newline Three test cases are performed to test the validity… More >

John L. Volakis¹, Kubilay Sertel¹, Erik Jørgensen², Rick W. Kindt¹

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.5, pp. 463-476, 2004, DOI:10.3970/cmes.2004.005.463

Abstract In this paper we address several topics relating to the development and implementation of volume integral and hybrid finite element methods for electromagnetic modeling. Comparisons of volume integral equation formulations with the finite element-boundary integral method are given in terms of accuracy and computing resources. We also discuss preconditioning and parallelization of the multilevel fast multipole method, and propose higher-order basis functions for curvilinear quadrilaterals and volumetric basis functions for curvilinear hexahedra. The latter have the desirable property of vanishing divergence within the element but non-zero curl. In addition, a new domain decomposition is introduced for solving array problems involving… More >

Ming-Hsiao Lee^1,2, Wen-Hwa Chen^1,3

CMES-Computer Modeling in Engineering & Sciences, Vol.61, No.3, pp. 249-272, 2010, DOI:10.3970/cmes.2010.061.249

Abstract The meshless method has a distinct advantage over other methods in that it requires only nodes without an element mesh which usually induces time-consuming work and inaccuracy when the elements are distorted during the analysis process. However, the element mesh can provide more geometry information for numerical simulation, without the need to judge if the nodes or quadrature points are inside the analysis domain which happens in the meshless method, since the analysis domain is defined by the element's edges or faces and the quadrature points are all inside the elements. Because the analysis model with only nodes for the… More >

M. Marigo^1,2, D. L. Cairns¹, M. Davies¹, M. Cook³,A. Ingram^2,4,5, E. H. Stitt¹

CMES-Computer Modeling in Engineering & Sciences, Vol.59, No.3, pp. 217-238, 2010, DOI:10.3970/cmes.2010.059.217

Abstract In this work the complex motion of the Turbulamixer has been measured by Multiple-Positron Emission Particle Tracking (Multiple PEPT) in order to set-up a DEM numerical model. Positron emitting radioactive tracers were attached to three of the pivot bearings on the shaft of the mixer to enable the rotation and translation of the mixer chamber to be tracked in the PEPT camera. The measured movement was mathematically reconstructed and imported into DEM in order to apply the same movement to the modelled vessel. The three-dimensional motion of particles in a vessel located in the Turbula mixer was then calculated using… More >

Yaoming Zhang¹, Yan Gu¹, Jeng-Tzong Chen²

CMES-Computer Modeling in Engineering & Sciences, Vol.50, No.1, pp. 1-20, 2009, DOI:10.3970/cmes.2009.050.001

Abstract There exist nearly singular integrals for thin walled structures in the boundary element method (BEM). In this paper, an efficient analytical method is developed to deal with the nearly singular integrals in the boundary integral equations (BIEs) for 2-D thin walled structures. The developed method is possible for problems defined in high-order geometry elements when the nearly singular integrals need to be calculated. For the analysis of nearly singular integrals with high-order geometry elements, much fewer boundary elements can be used to achieve higher accuracy. More importantly, computational models of thin walled structures or thin shapes in structures demand a… More >

Y.M. Zhang¹, Y. Gu¹, J.T. Chen²

CMES-Computer Modeling in Engineering & Sciences, Vol.45, No.3, pp. 227-248, 2009, DOI:10.3970/cmes.2009.045.227

Abstract The accurate evaluation of nearly singular integrals is one of the major concerned problems in the boundary element method (BEM). Although the current methods have achieved great progress, it is often possible only for problems defined in the simplest geometrical domains when the nearly singular integrals need to be calculated. However, engineering processes occur mostly in complex geometrical domains, and always, involve nonlinearities of the unknown variables and its derivatives. Therefore, effective methods of dealing with nearly singular integrals for such practical problems are necessary and need to be further investigated. In this paper, a general strategy based on a… More >