V.A. Buryachenko^1,2, T.L. Jackson^2,3, G. Amadio³

CMES-Computer Modeling in Engineering & Sciences, Vol.85, No.5, pp. 379-416, 2012, DOI:10.3970/cmes.2012.085.379

Abstract We consider a composite medium, which consists of a homogeneous matrix containing a statistically homogeneous set of multimodal spherical inclusions. This model is used to represent the morphology of heterogeneous solid propellants (HSP) that are widely used in the rocket industry. The Lubachevsky-Stillinger algorithm is used to generate morphological models of HSP with large polydisperse packs of spherical inclusions. We modify the algorithm by proposing a random shaking procedure that leads to the stabilization of a statistical distribution of the simulated structure that is homogeneous, highly mixed, and protocol independent (in sense that the statistical More >

Kun Luan¹, Baozhong Sun¹, Bohong Gu^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.79, No.1, pp. 31-62, 2011, DOI:10.3970/cmes.2011.079.031

Abstract This paper reports finite element multi-scale simulations of ballistic impact damage of three-dimensional angle-interlock woven composite (3DAWC) penetrated under a hemispherical rigid projectile. A multi-scale geometrical model of the 3DAWC was established for the numerical simulation. The multi-scale geometrical model of the 3DAWC consists two parts: one is the microstructure model and another is the continuum model. The microstructure model has the same microstructure with that of the 3DAWC composite panel, including the fiber tows' diameter, fiber tow configuration and fiber volume fraction. The continuum model has the same mechanical properties with the 3DAWC. The… More >

J. Cugnoni¹, M. Galli²

CMES-Computer Modeling in Engineering & Sciences, Vol.66, No.2, pp. 165-186, 2010, DOI:10.3970/cmes.2010.066.165

Abstract With the progress of miniaturization, in many modern applications the characteristic dimensions of the physical volume occupied by particle-reinforced composites are getting comparable with the reinforcement size and many of those composite materials undergo plastic deformations. In both experimental and modelling contexts, it is therefore very important to know whether, and up to which characteristic size, the description of the composites in terms of effective, homogenized properties is sufficiently accurate to represent their response in the actual geometry. Herein, the case of particle-reinforced composites with elastoviscoplastic matrix materials and polyhedral randomly arranged linear elastic reinforcement… More >

Yang Yang¹, Anil Misra²

CMES-Computer Modeling in Engineering & Sciences, Vol.64, No.1, pp. 1-36, 2010, DOI:10.3970/cmes.2010.064.001

Abstract Gradient theories have found wide applications in modeling of strain softening phenomena. This paper presents a higher order stress-strain theory to describe the damage behavior of strain softening materials. In contrast to most conventional gradient approaches for damage modeling, the present higher order theory considers strain gradients and their conjugate higher-order stress such that stable numerical solutions may be achieved. We have described the derivation of the required constitutive relationships, the governing equations and its weak form for this higher-order theory. The constitutive coefficients were obtained from a granular media approach such that the internal More >

A. Papacharalampopoulos², G. F. Karlis², A. Charalambopoulos³, D. Polyzos⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.58, No.1, pp. 45-74, 2010, DOI:10.3970/cmes.2010.058.045

Abstract A Boundary Element Method (BEM) for solving two (2D) and three dimensional (3D) dynamic problems in materials with microstructural effects is presented. The analysis is performed in the frequency domain and in the context of Mindlin's Form II gradient elastic theory. The fundamental solution of the differential equation of motion is explicitly derived for both 2D and 3D problems. The integral representation of the problem, consisting of two boundary integral equations, one for displacements and the other for its normal derivative is exploited for the proposed BEM formulation. The global boundary of the analyzed domain More >

H.K. Mebatsion^1,2, P. Verboven¹, P. T. Jancsók¹, Q.T. Ho¹, B.E. Verlinden³, B.M. Nicolaï^1,3

CMES-Computer Modeling in Engineering & Sciences, Vol.29, No.3, pp. 137-150, 2008, DOI:10.3970/cmes.2008.029.137

Abstract Transport processes of gas and moisture are among the most important physiological processes in plant tissue. Microscale transport models based on Navier-Stokes equations provide insight into such processes at the microscopic scale. Due to microscopic complexity, numerical solutions based on the finite element or finite volume methods are mandatory. Therefore, a 3D geometric model of the tissue is essential. In this article, a novel algorithm for geometric reconstruction of 2D slices of synchrotron tomographic images is presented. The boundaries of 2D cells on individual slices were digitized to establish a set of boundary coordinates and… More >

B. Yang^1,2, S.-C. Wong³, S. Qu³

CMES-Computer Modeling in Engineering & Sciences, Vol.24, No.2&3, pp. 81-94, 2008, DOI:10.3970/cmes.2008.024.081

Abstract In the modeling of overall property of composites, the effect of particle interaction has been either numerically taken into account within a (representative) volume element of a small number of particles or neglected/ignored in order for efficient solution to a large system of particles. In this study, we apply the point-defect Green's function (GF) to take into account the effect of particle interaction. It is applicable to small volume fractions of particles (within 10 %). The high efficiency of the method enables a simulation of a large system of particles with generally elastic anisotropy, arbitrary… More >

K. Yashiro¹, Y. Nakashima¹, Y. Tomita¹

CMES-Computer Modeling in Engineering & Sciences, Vol.11, No.2, pp. 73-80, 2006, DOI:10.3970/cmes.2006.011.073

Abstract A simple back force model is proposed for a dislocation cutting into γ' precipitate, taking the work formaking and recovering an anti-phase boundary (APB) into account. The first dislocation, or a leading partial of a superdislocation, is acted upon by a back force whose magnitude is equal to the APB energy. The second dislocation, or a trailing partial of a superdislocation, is attracted by the APB with a force of the same magnitude. The model is encoded in the 3D discrete dislocation dynamics (DDD) code and applied to the cutting behavior of dislocations at a… More >

H. Payer¹, T. Haschke¹, R. Reichardt¹, G. Li², K. Graf^2,3, W. Wiechert^1,3

FDMP-Fluid Dynamics & Materials Processing, Vol.4, No.2, pp. 61-76, 2008, DOI:10.3970/fdmp.2008.004.061

Abstract Microstructured surfaces are of steadily increasing importance in a large variety of technological applications. For the purpose of quality assurance, e.g. during variation studies of experimental parameters or for comparison with results from simulations, the surface geometry must be precisely measured and described in terms of geometric parameters. An analysis tool for regularly structured surfaces is presented that performs a highly automated evaluation of surface scanning data and derives geometric quality control parameters. To demonstrate the power of the analysis tool it is exemplarily applied for the investigation of microcraters emerging after the evaporation of… 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 >