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Numerical Simulation of the Mechanical Properties of Sintered and Bonded Perforated Hollow Sphere Structures (PHSS)

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Journal of materials Science & Technology 2010年第8期26卷 730-736页

作者： Andreas chsner Seyed Mohammad Hossein Hosseini Markus Merkel Department of Applied Mechanics Technical University of Malaysia Centre for Mass and Mechanical Transport in Engineering materials The University of Newcastle CallaghanNewSouth Wales 2308Australia Department of Mechanical Engineering University of Applied Sciences Aalen

This paper investigated the uniaxial mechanical properties of a new type of hollow sphere structures. For this new type, the sphere shell was perforated by several holes in order to open the inner sphere volume and surface. The mechanical properties, i.e. elastic properties and initial yield stress of perforated hollow sphere structures （PHSS） in a primitive cubic arrangement were numerically evaluated for different hole diameters and different joining techniques of the hollow spheres. The results are compared to classical configurations without perforation.

关键词： Mechanical properties cellular material Porous structure Finite element method

Finite element simulations on the mechanical properties of MHS materials

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Acta Mechanica Sinica 2007年第1期23卷 65-75页

作者： Z. Y. Gao T. X. Yu D. Karagiozova Department of Mechanical Engineering Hong Kong University of Science &Technology Clear Water Bay Kowloon Hong Kong China Institute of Mechanics Bulgarian Academy of Sciences Acad. G. Bonchev Street Block 4 Sofia 1113 Bulgaria

Finite element simulations are carried out to examine the mechanical behavior of the metallic hollow sphere （MHS） material during their large plastic deformation and to estimate the energy absorbing capacity of these materials under uniaxial compression. A simplified model is proposed from experimental observations to describe the connection between the neighboring spheres, which greatly improves the computation efficiency. The effects of the governing physical and geometrical parameters are evaluated; whilst a special attention is paid to the plateau stress, which is directly related to the energy absorbing capacity. Finally, the empirical functions of the relative material density are proposed for the elastic modulus, yield strength and plateau stress for FCC packing arrangement of hollow spheres, showing a good agreement with the experimental results obtained in our previous study.

关键词： cellular material Hollow sphere Large plastic deformation Numerical simulation FEM

Structural modeling of sandwich structures with lightweight cellular cores

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Acta Mechanica Sinica 2007年第5期23卷 545-559页

作者： T.Liu Z.C.Deng T.J.Lu Department of Engineering Mechanics Northwestern Polytechnical UniversityXi'an 710072China MOE Key Laboratory of Strength and Vibration School of AerospaceXi'an Jiaotong UniversityXi'an 710049China

An effective single layered finite element （FE） computational model is proposed to predict the structural behavior of lightweight sandwich panels having two dimensional （2D） prismatic or three dimensional （3D） truss cores. Three different types of cellular core topology are considered： pyramidal truss core （3D）, Kagome truss core （3D） and corrugated core （2D）, representing three kinds of material anisotropy： orthotropic, monoclinic and general anisotropic. A homogenization technique is developed to obtain the homogenized macroscopic stiffness properties of the cellular core. In comparison with the results obtained by using detailed FE model, the single layered computational model can give acceptable predictions for both the static and dynamic behaviors of orthotropic truss core sandwich panels. However, for non-orthotropic 3D truss cores, the predictions are not so well. For both static and dynamic behaviors of a 2D corrugated core sandwich panel, the predictions derived by the single layered computational model is generally acceptable when the size of the unit cell varies within a certain range, with the predictions for moderately strong or strong corrugated cores more accurate than those for weak cores.

关键词： cellular material Sandwich panel Homogenization Finite element

Strain-rate effect on initial crush stress of irregular honeycomb under dynamic loading and its deformation mechanism

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Acta Mechanica Sinica 2018年第1期34卷 117-129页

作者： Peng Wang Zhijun Zheng Shenfei Liao Jilin Yu CAS Key Laboratory of Mechanical Behavior and Design of materials Department of Modern Mechanics University of Science and Technology of China Institute of Systems Engineering China Academy of Engineering Physics Institute of Fluid Physics China Academy of Engineering Physics

The seemingly contradictory understandings of the initial crush stress of cellular materials under dynamic loadings exist in the literature, and a comprehensive analysis of this issue is carried out with using direct information of local stress and strain. Local stress/strain calculation methods are applied to determine the initial crush stresses and the strain rates at initial crush from a cell-based finite element model of irregular honeycomb under dynamic loadings. The initial crush stress under constant-velocity compression is identical to the quasi-static one, but less than the one under direct impact, i.e. the initial crush stresses under different dynamic loadings could be very different even though there is no strain-rate effect of matrix material. A power-law relation between the initial crush stress and the strain rate is explored to describe the strain-rate effect on the initial crush stress of irregular honeycomb when the local strain rate exceeds a critical value, below which there is no strain-rate effect of irregular honeycomb. Deformation mechanisms of the initial crush behavior under dynamic loadings are also *** deformation modes of the initial crush region in the front of plastic compaction wave are different under different dynamic loadings.

关键词： cellular material Constant-velocity compression Direct impact Cross-sectional stress Initial crush stress Strain rate effect

Macrocellular vitreous carbon with the improved mechanical strength

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Frontiers of materials Science 2015年第4期9卷 413-417页

作者： Oleg SMORYGO Alexander MARUKOVICH Vitali MIKUTSKI Andika PRAMONO Powder Metallurgy Institute National Academy of Sciences of Belarus 41 Platonov str. Minsk 220005 Belarus Research Centre for Metallurgy and materials Indonesian Institute of Sciences (LIPI) Kawasan Puspitek 470 Serpong 15314 Banten Indonesia

Vitreous carbons with regular macrocellular structure, open intercon- nected porosity, high specific strength and hydraulic permeability were synthesized by infiltration of the epoxy resin into the sacrificial template made from the carbamide granules. Polyvinylpyrrolidone （PVP） solution in ethanol was used as the template binder. When the resin setting and the template extraction had been performed, the resultant porous material was pyrolysed in the nitrogen flow. Depending on PVP concentration in the template binder, final vitreous carbons had the following properties： bulk density at 0.17-0.22g/cm3; porosity at 85.7%-89.0%; window size at 447-735pm; Darcian permeability coefficient at （0.64-9.5）×10-9m2; non-Darcian permeability coefficient at （0.53-3.36）×10-4 m. High specific strength of above 8×10^3 Pa/（kg.m-3） was attained.

关键词： vitreous carbon cellular material porous material