S. Anup¹, S. M. Sivakumar², G. K. Suraishkumar³

CMES-Computer Modeling in Engineering & Sciences, Vol.18, No.2, pp. 145-154, 2007, DOI:10.3970/cmes.2007.018.145

Abstract Bone is a hierarchical bio-composite, and has a staggered arrangement of soft protein molecules interspaced with hard mineral platelets at the fine ultrastructure level. The investigation into reasons for high fracture toughness of bio-composites such as bone requires consideration of properties at the different levels of hierarchy. In this work, the analysis is done at the continuum level, but the properties used are appropriate to that of the level considered. In this way, the properties at the fine ultrastructure level of bone is considered in the stress distribution analysis of a platelet adjacent to the More >

D.S. Liu^1,2 , C.Y. Chen² , D.Y. Chiou³

CMES-Computer Modeling in Engineering & Sciences, Vol.9, No.2, pp. 179-192, 2005, DOI:10.3970/cmes.2005.009.179

Abstract A three-dimensional heterogeneous infinite element method (HIEM) for modeling inclusions with interphases in composite materials is presented. This special element is formulated based on the conventional finite element method (FEM) using the similarity stiffness property and matrix condensation operations. An HIE-FE coupling scheme is also developed and implemented using the commercial software ABAQUS to conduct the elastostatic analysis. The proposed approach was validated first to study heterogeneous material containing one spherical inclusion. The displacement and stress variations around the inclusion vicinity are verified against conventional FEM. The proposed approach was next applied to analyze the effective More >

Qing-Sheng Yang^1,2, Wilfried Becker³

CMES-Computer Modeling in Engineering & Sciences, Vol.6, No.4, pp. 319-332, 2004, DOI:10.3970/cmes.2004.006.319

Abstract The present paper focuses on the comparative investigation of different homogenization methods for fiber composites, void solids and rigid inclusion media. The effective properties of multi-phase media are calculated by three methods, i.e. direct average method of stress and strain, direct average method of strain energy and two-scale expansion method. A comprehensive comparison, in principle and numerically, of these methods is emphasized. It is obvious that the two direct average methods are identical in principle and therefore they give the same numerical results. It is shown that the two-scale expansion method is the same as More >

Changyu Hwang¹, Philippe H. Geubelle²

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.4, pp. 45-56, 2000, DOI:10.3970/cmes.2000.001.497

Abstract This paper presents the formulation and numerical implementation of a spectral scheme specially developed to simulate dynamic fracture events in unidirectional and cross-ply fiber-reinforced composites. The formulation is based on the spectral representation of the transversely isotropic elastodynamic relations between the traction stresses along the fracture plane and the resulting displacements. Example problems involving stationary or dynamically propagating cracks in fiber-reinforced composites are investigated and compared with reference solutions available in the literature and/or experimental observations. More >

N. D. Ngo, K. K. Tamma¹

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.3, pp. 57-72, 2000, DOI:10.3970/cmes.2000.001.359

Abstract In the process modeling via Resin Transfer Molding (RTM) for thick composite sections, multi-layer preforms with varying thermophysical characteristics across the different layers, or for geometrically complex mold geometries with varying thicknesses, the assumption of a thin shell-like geometry is no longer valid. The flow in the through thickness direction is no longer negligible and current practices of treating the continuously moving flow front as two-dimensional and the temperature and cure as three-dimensional are not representative of the underlying physics. In view of these considerations, in the present study, the focus is on the non-isothermal… More >

J.C. Michel¹, H. Moulinec, P. Suquet

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.2, pp. 79-88, 2000, DOI:10.3970/cmes.2000.001.239

Abstract An iterative numerical method based on Fast Fourier Transforms has been proposed by \cite{MOU98} to investigate the effective properties of periodic composites. This iterative method is based on the exact expression of the Green function for a linear elastic, homogeneous reference material. When dealing with linear phases, the number of iterations required to reach convergence is proportional to the contrast between the phases properties, and convergence is therefore not ensured in the case of composites with infinite contrast (those containing voids or rigid inclusions or highly nonlinear materials). It is proposed in this study to… More >

V. Carvelli², G. Maier², A. Taliercio²

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.2, pp. 19-30, 2000, DOI:10.3970/cmes.2000.001.179

Abstract Homogenization of periodic fiber-reinforced ductile composite materials is performed as for the material strength, i.e. the carrying capacity with respect to macroscopic (average) stresses. Rigid-plastic limit analysis is formulated by the kinematic theorem applied to the representative volume with periodicity boundary conditions and von Mises yield criterion. The iterative procedure adopted for the numerical solution of the minimization problem is comparatively discussed on the basis of applications to various ductile heterogeneous media. More >

Qiuren Ou^1,2,*, Peijun Ji², Jun Xiao¹, Ling Wu²

FDMP-Fluid Dynamics & Materials Processing, Vol.15, No.1, pp. 27-37, 2019, DOI:10.32604/fdmp.2019.04787

Abstract The properties of resin transfer molding (RTM) cyanate ester and its T800 grade carbon fiber composites were studied with the rheometer, differential scanning calorimetry (DSC), FT-IR, dynamic mechanical analyzer (DMA), thermal gravimetric analysis (TGA), mechanical property testing, and scanning electron microscopy (SEM). The results showed that the temperature of cyanate ester suitable for RTM process was 70℃. Curing process of the resin was 130℃/2 h+160℃/2 h+200℃/2 h+220℃/4 h. Glass transition temperature and heat decomposition temperature of the cured resin are 289℃ and 415℃, respectively. Mechanical properties of T800/RTM cyanate composites are 13.5% higher than that More >

Wenqi Zhang¹, Yunqing Gu^1,*, Jiegang Mou¹

FDMP-Fluid Dynamics & Materials Processing, Vol.14, No.4, pp. 243-258, 2018, DOI:10.32604/fdmp.2018.03836

Abstract It is of great significance for the production of micro robots and new sensors to develop actuators with “muscle” properties. As a kind of electroactive polymers (EAPs), IPMC (ionic polymer-metal composite) can exhibit significant deformation for very low electrical excitation. These composites, known as the “artificial muscle”, can be regarded as intelligent bionic materials. With regard to the mechanism of deformation of IPMC, a large number of experimental studies have proved that the variety of electrodes and water contents relating to IPMC have great influence on its electro-mechanical and mechanical properties. Recent research results about… More >

Munther Issa K,ah¹, Jean-Luc Meunier²

FDMP-Fluid Dynamics & Materials Processing, Vol.5, No.2, pp. 123-136, 2009, DOI:10.3970/fdmp.2009.005.123

Abstract Multi walled carbon nanotubes (MWCNTs) were synthesized on different graphite types covered with thin layer of nickel catalyst by catalytic chemical vapour deposition using acetylene as hydrocarbon source. The produced carbon nanotubes were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and transmission electron microscopy (TEM). The shape, quantity and diameter of the MWCNTs are shown to be affected by the type of the graphite substrate, the growth temperature and the hydrocarbon source flow rate. The diameters of the produced MWCNTs were ranged between 43 and 80 nm for pyrolytic (PYROID) and polycrystalline More >