Ligia Munteanu¹, Cornel Brisan², Veturia Chiroiu³, Stefania Donescu⁴

CMC-Computers, Materials & Continua, Vol.31, No.2, pp. 127-146, 2012, DOI:10.3970/cmc.2012.031.127

Abstract A modeling of the compression by using the property of Helmholtz equation to be invariant under geometric transformations is presented in this paper. The versatility of the geometric transformations is illustrated in order to obtain a new interpretation of the compression process. The physical spatial compression leads, most of the times, to new materials with inhomogeneous and anisotropic properties. The compression can be theoretically controlled by the geometric transformations. As an example, new architectures for auxetic materials can be built up by applying the geometric transformations. The new versions are finding their full correspondents in More >

Raghvendra Khedle¹, D.P.Mondal², S.N.Verma¹, Sanjay Panthi²

CMC-Computers, Materials & Continua, Vol.27, No.3, pp. 211-230, 2012, DOI:10.3970/cmc.2011.027.211

Abstract The interface in aluminum cenosphere syntactic foam (ACSF) is modeled using FEM to study its deformation behaviour as a function of interface characteristics such as interface stiffness and thickness. The interface is modeled as a thin layer of object. The effective modulus and stress of ACSF examined when it contain 50% cenosphere by volume. In this study, the shell wall thickness of cenosphere is fixed at 1µm. The width of the interface varies from 0.2% to 0.6% of cenosphere volume fraction. The interface strength and modulus varies in the range of 10 to 50% of the More >

Jin Ma¹, Jay C. Hanan¹, Ranga Komanduri¹, Hongbing Lu²

CMES-Computer Modeling in Engineering & Sciences, Vol.86, No.4, pp. 349-384, 2012, DOI:10.3970/cmes.2012.086.349

Abstract Amorphous metallic foams are an exciting class of materials for an array of high impact absorption applications, the mechanical behavior of which is only beginning to be characterized. To determine mechanical properties, guide processing, and engineer the microstructure for impact absorption, simulation of the mechanical properties is necessary as experimental determination alone can be expensive and time consuming. In this investigation, the material point method (MPM) with C1 continuous shape function is used to simulate the response of a bulk metallic glass (BMG) closed-cell foam (Pd42.5Cu30Ni7.5P20) under compression. The BMG foam was also tested experimentally… More >

Weiwei Gong, Yan Liu, Xiong Zhang, Honglei Ma

CMES-Computer Modeling in Engineering & Sciences, Vol.83, No.5, pp. 527-546, 2012, DOI:10.3970/cmes.2012.083.527

Abstract Owing to its low density and good energy absorption capability, aluminum foam is an excellent protective material for spacecraft against debris impact. However, because of its complicated microstructure, it is very difficult to generate a FEM mesh accounting for the real microstructure of the alluminum foam. On the contrary, it is very easy to model three-dimensional problems with very complicated geometry with meshfree/meshless methods. Furthermore, the material point method has obvious advantages in modeling problems involving extreme large deformation problems like hypervelocity impact problem. In this paper, a three-dimensional material point model accounting for the More >

Hanxing Zhu

The International Conference on Computational & Experimental Engineering and Sciences, Vol.17, No.4, pp. 131-132, 2011, DOI:10.3970/icces.2011.017.131

Abstract This paper aims to study the size-dependent elastic properties of micro- and nano-sized open-celled foams. To simplify the analysis, we use perfect regular body-centered cubic structure (i.e. BCC foam), which has cubic symmetry and only three independent elastic constants. Taking strut bending, twisting and axial compression/stretching as the deformation mechanisms, Zhu, Knott and Mills (JMPS, V45, pp. 319-343, 1997) have obtained closed form results of all the three independent elastic constants (i.e. the Young's modulus E11 , the shear modulus G12 and the Poisson ratio v12 ) as functions of the bending stiffness, the torsional… More >

Yishan Pan, Xiangfeng Lv, Zhonghua Li, XiChun Xiao

The International Conference on Computational & Experimental Engineering and Sciences, Vol.16, No.4, pp. 101-102, 2011, DOI:10.3970/icces.2011.016.101

Abstract Geometry size has a great influence on energy absorption ability of closed-cell foam metals. Study on energy absorption ability of closed-cell Si-Al foam metals considering geometry size by impact experiment method. The results show that the strain and absorbing energy value are decreasing with the geometry size increasing, and also lead to the hole wall rupture or whole instability. The best height-width ratio for cube and cylinder are 1.0~1.5 and 1.0~2.0, respectively. With the increasing of material diameter, the compressive strength increasing quickly, but the strain reduces. It is clearly that height-width ratio 1.0 is More >

Weiwei Gong¹, Xiong Zhang^1,2, Xinming Qiu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.82, No.3&4, pp. 195-214, 2011, DOI:10.32604/cmes.2011.082.195

Abstract Due to its high strength, low weight and strong anti impact capability, aluminum foam has great potential in the fields of transportation, aerospace and building structures as energy absorbing materials. Due to its complicated microstructures, it is desirable to develop an efficient numerical method to study the dynamic response of the aluminum foam under impact loading. In this paper, the material point method (MPM) is extended to the numerical simulation of the dynamic response of the aluminum foam under impact loading by incorporating the Deshpande Fleck's model and a volumetric strain failure model into our More >

B. Madani¹, F. Topin², L. Tadrist²

FDMP-Fluid Dynamics & Materials Processing, Vol.6, No.4, pp. 351-368, 2010, DOI:10.3970/fdmp.2010.006.351

Abstract The present work deals with the hydraulic characterization of two-phase flow with phase change in a channel filled with metallic foam. We provide a general presentation of metallic foams including morphological characteristics, fabrication processes and industrial applications. The experimental facility, which consists of a hydrodynamic loop, the test section, measurement devices, and the data acquisition system, is presented. The Metallic foam sample tested in the present work is manufactured by SCPS (French manufacturer). N-pentane is used as a coolant fluid. The mass velocity values lie between 4 and 49 kg/ m2s, while the heating power More >

H. Altenbach¹, V. A. Eremeyev²

CMC-Computers, Materials & Continua, Vol.9, No.2, pp. 153-178, 2009, DOI:10.3970/cmc.2009.009.153

Abstract Within the framework of the direct approach to the plate theory we consider natural oscillations of plates made of functionally graded materials taking into account both the rotatory inertia and the transverse shear stiffness. It is shown that in some cases the results based on the direct approach differ significantly from the classical estimates. The reason for this is the non-classical computation of the transverse shear stiffness. More >

Mehmet Satar¹, Emin Turhan¹, Hacer Yapicioglu¹, Nejat Narli¹, Fatma Tuncay Ozgunen², Salih Çetiner³

European Cytokine Network, Vol.19, No.1, pp. 37-41, 2008, DOI:10.1684/ecn.2008.0118

Abstract The purpose of this study was to determine cord blood cytokine levels and their relationship with morbidity and mortality in neonates with prolonged, premature rupture of membranes (PPROM). Forty two premature neonates of 29-35 weeks gestational age with PPROM exceeding 24 hours were considered as the PPROM group and simultaneously, 41 premature neonates without PPROM were considered as the control group. All the neonates were admitted to the Neonatology Unit for further evaluation of subsequent complications such as early neonatal sepsis, pneumonia, intraventicular haemorrhage (IVH), respiratory distress syndrome (RDS), necrotizing enterocolitis (NEC) and chronic lung… More >