Giacomo Landi¹, Surya R. Kalidindi²

CMC-Computers, Materials & Continua, Vol.16, No.3, pp. 273-294, 2010, DOI:10.3970/cmc.2010.016.273

Abstract In this paper, we present a computationally efficient multi-scale framework for predicting the local fields in the representative volume element of a multiphase material system subjected to thermo-mechanical loading conditions. This framework for localization relationships is a natural extension of our recent work on two-phase composites subjected to purely mechanical loading. In this novel approach, the localization relationships take on a simple structure expressed as a series sum, where each term in the series is a convolution product of local structure and the governing physics expressed in the form of influence coefficients. Another salient feature More >

Dustin D. Gerrard¹, David T. Fullwood¹, Denise M. Halverson², Stephen R. Niezgoda³

CMC-Computers, Materials & Continua, Vol.15, No.2, pp. 129-152, 2010, DOI:10.3970/cmc.2010.015.129

Abstract The effective properties of composite materials are often strongly related to the connectivity of the material components. Many structure metrics, and related homogenization theories, do not effectively account for this connectivity. In this paper, relationships between the topology, represented via homology theory, and the effective elastic response of composite plates is investigated. The study is presented in the context of popular structure metrics such as percolation theory and correlation functions. More >

M.V. Menshykova¹, I.A. Guz, O.V. Menshykov

CMES-Computer Modeling in Engineering & Sciences, Vol.51, No.3, pp. 239-260, 2009, DOI:10.3970/cmes.2009.051.239

Abstract The present work is devoted to the investigation of the internal instability in laminated materials. The paper is concerned with the development of a unified computational procedure for numerical realisation of the method as applied to various constitutive equations of the layers, different loading schemes (uniaxial or biaxial loading) and different precritical conditions (large or small precritical deformations). It contains many examples of critical stresses/strains calculations for particular composites as well as analysis of different buckling modes. More >

D.T. Fullwood¹, S.R. Kalidindi², B.L. Adams¹, S. Ahmadi¹

CMC-Computers, Materials & Continua, Vol.9, No.1, pp. 25-40, 2009, DOI:10.3970/cmc.2009.009.025

Abstract Localization relations arise naturally in the formulation of multi-scale models. They facilitate statistical analysis of local phenomena that may contribute to failure related properties. The computational burden of dealing with such relations is high and recent work has focused on spectral methods to provide more efficient models. Issues with the inherent integrations in the framework have led to a tendency towards calibration-based approaches. In this paper a discrete Fourier transform framework is introduced, leading to an extremely efficient basis for the localization relations. Previous issues with the Green's function integrals are resolved, and the method More >

C.M. Hefferan¹, S.F. Li¹, J. Lind¹, U. Lienert², A.D. Rollett³, P. Wynblatt³, R.M. Suter^1,3

CMC-Computers, Materials & Continua, Vol.14, No.3, pp. 209-220, 2009, DOI:10.3970/cmc.2009.014.209

Abstract We have measured and reconstructed via forward modeling a small volume of microstructure of high purity, well annealed nickel using high energy x-ray diffraction microscopy (HEDM). Statistical distributions characterizing grain orientations, intra-granular misorientations, and nearest neighbor grain misorientations are extracted. Results are consistent with recent electron backscatter diffraction measurements. Peaks in the grain neighbor misorientation angle distribution at 60 degrees (∑3) and 39 degrees (∑9) have resolution limited widths of ≈ 0.14 degree FWHM. The analysis demonstrates that HEDM can recover grain and grain boundary statistics comparable to OIM volume measurements; more extensive data sets More >

S.Ahmadi¹, B.L.Adams¹ , D.T.Fullwood¹

CMC-Computers, Materials & Continua, Vol.14, No.2, pp. 141-170, 2009, DOI:10.3970/cmc.2009.014.141

Abstract In this paper, a model is introduced to examine the evolution of the microstructure function under plastic deformations. This model is based upon a double continuity relationship that conserves both material particles in the mass space and orientations in the orientation space. An Eulerian description of the motion of material particles and orientations is considered, and continuity relations are derived for both spaces. To show how the proposed model works, two different case studies are provided. In the mass space, the continuity relation is used to examine the evolution of the microstructure function of a More >

Xiaohua Hu¹, Gordana A. Cingara¹, David S. Wilkinson¹, Mukesh Jain², PeidongWu², Raja K. Mishra³

CMC-Computers, Materials & Continua, Vol.14, No.2, pp. 99-124, 2009, DOI:10.3970/cmc.2009.014.099

Abstract This work aims to understand the texture distribution in the localized necking band formed during uni-axial tension of AA5754 using an edge-constrained, plane strain post-necking FE model. The model domain is a long cross section of the band. Initial grain structure is mapped into the mesh from EBSD data using a modified Voroni-cell interpolation and considering pre-straining prior to localized necking. The material points in grains are assumed to exhibit isotropic elastoplastic behavior but have a relative strength in terms of Taylor factors which are updated by a Taylor-Bishop-Hill model. The predicted textures and gradients More >

Stephen R. Niezgoda¹, Surya R. Kalidindi^1,2

CMC-Computers, Materials & Continua, Vol.14, No.2, pp. 79-98, 2009, DOI:10.3970/cmc.2009.014.079

Abstract The generalized Hough transform is a common technique for feature detection in image processing. In this paper, we develop a size invariant Hough framework for the detection of arbitrary shapes in three dimensional digital microstructure datasets. The Hough transform is efficiently implemented via kernel convolution with complex Hough filters, where shape is captured in the magnitude of the filter and scale in the complex phase. In this paper, we further generalize the concept of a Hough filter by encoding other parameters of interest (e.g. orientation of plate or fiber constituents) in the complex phase, broadening More >

K. G. Wang¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.5, No.3, pp. 179-186, 2008, DOI:10.3970/icces.2008.005.179

Abstract Microstructural modeling is very important because it can provide a critical link between properties, mesoscopic length scale, and atomistic scale (multiscale modeling). There exist a couple of models and simulations to study microstructural evolution. It will be important and useful to discover unified model equations hidden in microstructure evolution. In this paper, I will derive the unified model equations for microstructure evolution. The governing equations in Lifshitz-Slyozov-Wagner theory and diffusion screening theory that modeled microstructural evolution are derived with some approximations from the unified model equations. The governing equations in multiparticle diffusion simulation and phase-field More >

H. T. Wang, G. Hall, S. Y. Yu, Z. H. Yao

CMES-Computer Modeling in Engineering & Sciences, Vol.37, No.2, pp. 153-174, 2008, DOI:10.3970/cmes.2008.037.153

Abstract Graphite materials are widely used in gas-cooled nuclear reactors as both moderators and reflectors. The graphite properties change when the microstructure damage occurs due to the in-core radiation and oxidation, thereby having a strong impact on the service life of graphite. In this paper, the X-ray tomography and the boundary element method (BEM) are introduced to the microstructure modeling and numerical simulations of both the mechanical and thermal property changes of nuclear graphite due to radiolytic oxidation. The model is established by the three-dimensional X-ray scan on the isotropic nuclear graphite Gilsocarbon, which is used… More >