C. A. Bronkhorst^1,2, A. R. Ross³, B. L. Hansen¹, E. K. Cerreta², J. F. Bingert²

CMC-Computers, Materials & Continua, Vol.17, No.2, pp. 149-174, 2010, DOI:10.3970/cmc.2010.017.149

Abstract A common sample geometry used to study shear localization is the "tophat": an axi-symmetric sample with an upper "hat" portion and a lower "brim" portion. The gage section lies between the hat and brim. The gage section length is on the order of 0.9 mm with deformation imposed through a Split-Hopkinson Pressure Bar system at maximum top-to-bottom velocity in the range of 10-25 m/sec. Detailed metallographic analysis has been performed on sections of the samples to quantify the topology and deformation state of the material after large deformation shear. These experiments performed with polycrystalline tantalum… More >

T.M. Hatem¹, M.A. Zikry¹

CMC-Computers, Materials & Continua, Vol.17, No.2, pp. 127-148, 2010, DOI:10.3970/cmc.2010.017.127

Abstract A three-dimensional multiple-slip dislocation-density-based crystalline formulation, and specialized finite-element formulations were used to investigate dislocation-density evolution and crack behavior in single-packet lath martensite in high strength martensitic steels. The formulation is based on accounting for variant morphologies and orientations, and initial dislocations-densities that are uniquely inherent to martensitic microstructures. The effects of loading plane with respect to the orientation o the habit plane are investigated. Furthermore, the formulation was used to investigate single-packet microstructure mapped directly from SEM/EBSD images of maraging and ausformed martensitic steel alloys. This analysis underscores that shear pipe effects in martensitic More >

I-L. Chang¹, W.-C. Ding

CMES-Computer Modeling in Engineering & Sciences, Vol.68, No.3, pp. 297-312, 2010, DOI:10.3970/cmes.2010.068.297

Abstract Molecular dynamics method incorporating with parallel computing technique was employed to study the mechanical properties of textured polycrystalline nanofilms with fixed out-of-plane normal direction. The grain size and film thickness effects on both the elastic and plastic properties of the copper nanofilm were examined. It is shown from the simulation that the elastic and plastic properties (i.e., Young’s modulus, Poisson’s ratio, biaxial yield stress, etc) of textured polycrystalline nanofilms depend on the grain size and the film thickness. As the grain size of the nanofilm become larger, the Young’s modulus and biaxial yield stress increase More >

Surkay D. Akbarov^1,2, Nazmiye Yahnioglu³, Ayfer Tekin⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.64, No.2, pp. 147-186, 2010, DOI:10.3970/cmes.2010.064.147

Abstract A three-dimensional buckling delamination problem for the sandwich rectangular plate made from elastic and viscoelastic material is studied. It is supposed that the plate contains interface rectangular cracks (Case 1) and interface rectangular edge-cracks (Case 2) and edge-surfaces of these cracks have initial infinitesimal imperfections. The evolution of these initial imperfections with an external compressive loading acting along the cracks (for a case where the materials of layers of the plate are elastic) or with duration of time (for a case where the materials of layers of the plate are viscoelastic) is investigated within the… More >

E. Tonti, F. Zarantonello¹

CMES-Computer Modeling in Engineering & Sciences, Vol.64, No.1, pp. 37-70, 2010, DOI:10.3970/cmes.2010.064.037

Abstract This paper completes a preceeding paper on the algebraic formulation of elastostatics [Tonti, Zarantonello (2009)]. It shows how to obtain a numerical formulation for elastodynamics by avoiding any process of discretization of differential equations, i.e. PDE-free formulation. To this end, we must analyse in more detail the discretization of time by highlighting the need to introduce a dual subdivision of the time axis, as we did for a space cell complex. The mass matrix obtained with the direct algebraic formulation is diagonal. More >

Z Damian-Noriega¹, PA Lomeli-Mejia², SA Villanueva-Pruneda¹, R Pérez-Moreno¹, JPA Puerta-Huerta¹, E Montes-Estrada¹, GD Alvarez-Miranda¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.14, No.1, pp. 29-36, 2010, DOI:10.3970/icces.2010.014.029

Abstract The sizing of the component parts of a mechanical assembly must first assure its assembly and functionality and then the replacement (interchangeability) of used parts with new parts. For diametral fits (gaps and interferences) the ISO system of limits and fits is used, but for axial gaps the functional dimensioning method is applied to ensure maximum and minimum functional values. For each axial gap, the axial dimensions of the involved parts must be identified. Later, a minimal chain of dimensions is established, defined as the addition and subtraction of vectors parallel to the axis of More >

T. Podoba¹, L. Tomsu¹, K. Vlcek¹, M. Heczko

The International Conference on Computational & Experimental Engineering and Sciences, Vol.15, No.4, pp. 111-122, 2010, DOI:10.3970/icces.2010.015.111

Abstract Surface reconstruction based on chaotic systems or exactly given point clouds is very difficult area. Current algorithms such as Marching Cube or Voronoi Filtering do not use methods based on artificial intelligence. In this paper, we investigate solution of polygonal surface construction based on AI. The main purpose is to generate complex polygonal mesh structures based on strange attractors with fractal structure. Attractors have to be created as 4D objects using quaternion algebra or using methods of AI. Polygonal mesh can have different numbers of polygons because of iterative application of this system. Our main More >

A. Grebennikov¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.15, No.3, pp. 85-90, 2010, DOI:10.3970/icces.2010.015.085

Abstract New General Ray (GR) method for solution of the Dirichlet boundary value problem for the class of elliptic Partial Differential Equations (PDE) is proposed. GR-method consists in application of the Radon transform directly to the PDE and in reduction PDE to assemblage of Ordinary Differential Equations (ODE). The class of the PDE includes the Laplace, Poisson and Helmgoltz equations. GR-method presents the solution of the Dirichlet boundary value problem for this type of equations by explicit analytical formulas that use the direct and inverse Radon transform. Proposed version of GR-method justified theoretically, realized by fast algorithms and More >

B.Cheng¹, R.K.L. Su¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.15, No.3, pp. 75-84, 2010, DOI:10.3970/icces.2010.015.075

Abstract Deep reinforced concrete (RC) coupling beams with low shear span ratios and conventionally reinforced shear stirrups tend to fail in a brittle way with limited ductility and deformability under reversed cyclic loading. Experimental studies have shown that bolting restrained steel plate (BRSP) to existing deep RC coupling beams can enhance the deformability and energy dissipation while maintaining the flexural stiffness, improving the beams' performance during an earthquake. In this study, a nonlinear finite element package ATENA was used to simulate the overall behavior of three previously tested BRSP retrofitted coupling beams. This paper presents the More >

L. Zhang¹, T. Boulet¹, J. Hein¹, M. Arnoult¹, M. Negahban¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.15, No.2, pp. 37-46, 2010, DOI:10.3970/icces.2010.015.037

Abstract The modeling of the response of the human head to blast like loading is of importance for many applications including the study of traumatic brain injury resulting from improvised explosive devices. One key issue in simulating the response of the head is to have models that are characteristic of the response of the head and its components under these conditions. We review different characterization efforts for evaluating the response of the skin, skull, and brain within this window of response and use these results to develop models appropriate for the characterization of each component. We More >