G. Haasemann¹, M. Kästner², V. Ulbricht³

CMES-Computer Modeling in Engineering & Sciences, Vol.42, No.1, pp. 35-58, 2009, DOI:10.3970/cmes.2009.042.035

Abstract The purpose of this paper is the presentation of a new efficient modelling strategy based on the combination of Binary Model and Extended Finite Element Method (X-FEM). It is applied to represent the internal architecture of textile reinforced composites where the resin-saturated fabric is characterised by a complex geometry. Homogenisation methods are used to compute the effective elastic material properties. Thereby, the discrete formulation of periodic boundary conditions is adapted regarding additional degrees of freedom used by finite elements which are based on the X-FEM. Finally, the results in terms of effective material properties reveal More >

S.H. Pyo¹, H.K. Lee^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.40, No.3, pp. 271-306, 2009, DOI:10.3970/cmes.2009.040.271

Abstract This paper presents a micromechanical approach for predicting the elastic and multi-level damage response of aligned and randomly oriented whisker-/ short fiber-reinforced composites. Based on a combination of Eshelby's micromechanics and the evolutionary imperfect interface approach, the effective elastic moduli of the composites are derived explicitly. The modified Eshelby's tensor for spheroidal inclusions with slightly weakened interface [Qu (1993b)] is extended in the present study to model whiskers or short fibers having mild or severe imperfect interfaces. Aligned and random orientations of spheroidal reinforcements are considered. A multi-level damage model in accordance with the Weibull's 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 >

Yang Pu¹, Xiang Zhihai¹, Hu Xiasong², Li Guorong², Zhu Haili², Mao XiaoqinCen², Zhangzhi^1,3

CMC-Computers, Materials & Continua, Vol.10, No.2, pp. 117-138, 2009, DOI:10.3970/cmc.2009.010.117

Abstract This paper studies the influence of root reinforcement on shallow soil protection by using Finite Element (FE) method. Taking the root-soil composite as a periodic material, the homogenization method is used to construct a Representative Volume Element (RVE) that consists of roots and soil. This RVE is discretized by a two-dimensional (2-D) FE mesh, while special formulation is established so that this model is capable of describing three-dimensional (3-D) deformations when the strain is invariant along the fiber axis. The important effect of debonding on the interface between the fiber and the matrix is also More >

K.K. Kratmann^1,3, M.P.F. Sutcliffe², L.T. Lilleheden³, O.T. Thomsen¹, R. Pyrz¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.7, No.1, pp. 7-12, 2008, DOI:10.3970/icces.2008.007.007

Abstract This paper concerns the quantification of fibre misalignment in unidirectional carbon fibre reinforced polymer composites (UD CFRP). The motivation for determining the fibre misalignment is described and existing applicable methods are presented. The concept of a newly developed image analysis procedure is described and the test procedures used to verify the robustness and precision of the method are presented along with selected results. More >

Mijia Yang¹, Qiao Pizhong²

The International Conference on Computational & Experimental Engineering and Sciences, Vol.6, No.3, pp. 157-168, 2008, DOI:10.3970/icces.2008.006.157

Abstract A new fatigue model suitable for polymer matrix composites is proposed, based on dimensional analysis of testing and material variables involved in a fatigue test. The new model has a good physical and theoretical foundation based on progressive damage, and unifies all the material and testing parameters into one general equation. Especially, the model can be simplified to the Goodman relation or Gerber relation when capturing the effect of mean stresses. The model suggested can be used to substitute the classical S-N curves and reduce the testing number by 50{\%} required by ASTM standards. A More >

M.V.Hosur¹, M. M. Islam, S. Jeelani

The International Conference on Computational & Experimental Engineering and Sciences, Vol.6, No.1, pp. 81-90, 2008, DOI:10.3970/icces.2008.006.081

Abstract In this paper, low-velocity impact response of braided composites is presented. Three types of braided fabrics were used. They were:$\pm$45, 0/$\pm$45, and 0/$\pm$60. Laminates with 7 layers of$\pm$45 and 4 layers of 0/$\pm$45, and 0/$\pm$60 were fabricated by vacuum assisted resin infusion molding process to get an average thickness ranging from 2.25 to 2.4 mm. Samples of size 10$\times$ 10 cm were then cut from the panels and impacted at 10, 20 and 30 J. Impact parameters like peak load and absorbed energy were calculated and normalized for thickness. All the samples were then subjected More >

A.N. Guz¹, J.J.Rushchitsky¹, I.A.Guz²

CMES-Computer Modeling in Engineering & Sciences, Vol.26, No.3, pp. 139-156, 2008, DOI:10.3970/cmes.2008.026.139

Abstract The basic approach is offered for problems of nanocomposites and their mechanical properties, which includes a short review of modern problems in nanomechanics of materials. The fibrous carbon-polymer composites with carbon or graphite microfibers or carbon nanotubes are especially discussed. The basic model of the linear or nonlinear elastically deforming micro- and nanocomposites is considered. Within the framework of this model, the comparative computer modeling is performed. The modeling permits to observe the features in prediction of values of basic mechanical constants. These results are utilized on next step of modeling -- studying the peculiarities More >

M. Patrício¹, R. Mattheij², G. de With³

CMES-Computer Modeling in Engineering & Sciences, Vol.38, No.2, pp. 89-118, 2008, DOI:10.3970/cmes.2008.038.089

Abstract The behaviour of composite materials with periodically distributed constituents is considered. Mathematically, this can be described by a boundary value problem with highly oscillatory coefficient functions. An algorithm is proposed to handle the case when the underlying periodicity is locally disturbed. This procedure is constructed using fundamental concepts from homogenisation theory and domain decomposition techniques. Applications to layered materials are considered. More >

D. H. Pahr¹, H.J. Böhm¹

CMES-Computer Modeling in Engineering & Sciences, Vol.34, No.2, pp. 117-136, 2008, DOI:10.3970/cmes.2008.034.117

Abstract The combination of heterogeneous volume elements and numerical analysis schemes such as the Finite Element method provides a powerful and well proven tool for studying the mechanical behavior of composite materials. Periodicity boundary conditions (PBC), homogeneous displacement boundary conditions (KUBC) and homogeneous traction boundary conditions (SUBC) have been widely used in such studies. Recently Pahr and Zysset (2008) proposed a special set of mixed uniform boundary conditions (MUBC) for evaluating the macroscopic elasticity tensor of human trabecular bone. These boundary conditions are not restricted to periodic phase geometries, but were found to give the same… More >