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 >

W. Li¹ and T. Siegmund¹

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.1, pp. 81-90, 2004, DOI:10.3970/cmes.2004.005.081

Abstract Results of a computational study of the mechanics of indentation induced interface delamination are described for a system consisting of a ductile film on an elastic substrate. Special attention is paid to the properties of the interface between film and substrate, and the influence of the interface properties on the indentation response. Specifically, strong interfaces are considered. The interface is characterized by the use of a cohesive zone model. The finite element method is used to solve the boundary value problem, with the interface behavior incorporated via a cohesive model in a traction-separation formulation. The More >

Y. W. Kwon¹, K. Roach¹

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.1, pp. 63-72, 2004, DOI:10.3970/cmes.2004.005.063

Abstract A micromechanical unit-cell model was developed for 2/2-twill woven fabric composites so that the model could be implemented for the multi-scale micro/macro-mechanical analysis of 2/2-twill composite structures. The unit-cell model can compute effective material properties of a 2/2-twill composite and decompose the effective stresses (strains) of the woven fabric composite into the stresses (strains) of the tows. When this unit-cell module is incorporated into the multi-scale analysis by combining with other modules developed previously, the residual strength and stiffness of a laminated structure made of 2/2-twill woven fabric composites can be predicted along with damage 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 >

Youping Chen¹, James D Lee², Azim Esk,arian¹

CMES-Computer Modeling in Engineering & Sciences, Vol.5, No.1, pp. 35-44, 2004, DOI:10.3970/cmes.2004.005.035

Abstract This paper addresses the need of theories and simulations for material body of mesoscopic and microscopic sizes. An overview of polar theories is presented. The micropolar theory proposed by Eringen is introduced and compared with other polar theories. Constitutive equations of micropolar thermo-visco-elastic solid are derived. Finite element analyses have been performed for a few sample problems with wide range of length scales. Based on the discussion, comparison and computer simulations, the unique feature and applicability of micropolar theory are demonstrated. More >

Chih-Ping Wu¹, Yen-Wei Chi¹

CMC-Computers, Materials & Continua, Vol.1, No.4, pp. 337-352, 2004, DOI:10.3970/cmc.2004.001.337

Abstract Within the framework of the three-dimensional (3D) nonlinear elasticity, a refined asymptotic theory is developed for the nonlinear analysis of laminated circular cylindrical shells. In the present formulation, the basic equations including the nonlinear relations between the finite strains (Green strains) and displacements, the nonlinear equilibrium equations in terms of the Kirchhoff stress components and the generalized Hooke's law for a monoclinic elastic material are considered. After using proper nondimensionalization, asymptotic expansion, successive integration and then bringing the effects of transverse shear deformation into the leading-order level, we obtain recursive sets of the governing equations… More >

Jiayong Tian^1,2, Ulrich Gabbert², Harald Berger², Xianyue Su¹

CMC-Computers, Materials & Continua, Vol.1, No.4, pp. 327-336, 2004, DOI:10.3970/cmc.2004.001.327

Abstract In this paper, we investigate Lamb wave interaction with delamination in an infinite carbon fiber reinforced plastics (CFRP) laminate by a hybrid method. The infinite CFRP laminate is divided into an exterior zone and an interior zone. In the exterior zone, the wave fields are expressed by wave mode expansion. In the interior zone, the wave fields are modeled by the finite element method (FEM). Considering the continuity condition at the boundary between the exterior and interior zones, the global wave fields can be calculated. Lastly, numerical examples show how a delamination in the laminate More >

Youssef F. Rashed¹

CMC-Computers, Materials & Continua, Vol.1, No.4, pp. 319-326, 2004, DOI:10.3970/cmc.2004.001.319

Abstract The present paper develops a new technique for treatment of self-weight for building slabs in the boundary element method (BEM). Due to the use of BEM in the analysis, all defined variables are presented on the slab boundary (mesh is defined only along the slab boundary). Self-weight, however, is usually defined over slab domain, hence domain discretisation is required, which spoils the main advantage of the BEM. In this paper a new method is presented to transform self-weight domain integrals to the boundary for such slabs. The proposed method is based on using the so-called More >

Kunigal N.Shivakumar¹, Shivalingappa Lingaiah², Robert Sadler², Matthew Sharpe²

CMC-Computers, Materials & Continua, Vol.1, No.4, pp. 309-318, 2004, DOI:10.3970/cmc.2004.001.309

Abstract The exfoliation and dispersion of nanoclay (2% by weight) and nanovermiculite (2% by weight) particles in a polymer matrix is analyzed using the Scanning Electron Microscope (SEM) after a low temperature air plasma etch. The plasma etch preferentially removes the polymer to expose the nanoparticles. Both Argon and air have been used as the etching media to study the etching process. SEM analysis illustrate the results of the etching in flat and edge surfaces of both nanoclay (MMT) and nanovermiculite (VMT) filled polymer. Both the MMT and VMT were dispersed using a IKA high shear More >

J. Qiu¹, T. Hayase¹, T. Okutani¹

CMC-Computers, Materials & Continua, Vol.1, No.4, pp. 301-308, 2004, DOI:10.3970/cmc.2004.001.301

Abstract In this study, three types of surface motion of wall motion actuators were proposed and used to control the Tollmien-Schlichting (T-S) wave in the laminar boundary layer of a plate. These three types of motion are standing transverse wave (with out-of-plane displacement), traveling transverse wave (with out-of-plane displacement) and standing longitudinal wave (with in-plane displacement). The length of a wall motion actuator was set to 1, 2 or 3 cycles of waveform. Numerical simulation was performed on the generation of T-S wave and its suppression with the three types of surface motion of the wall More >