Papers by Keyword: Poisson's Ratio

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Authors: Jian Han, Xi Tao Gao
Abstract: The tensile mechanical properties of bamboo mat and curtain plywood(for short bamboo plywood)were studied through “electrometric method”. It was proved that in the range of elastic deformation,the Poisson′s ratio and the elastic modulus of the bamboo plywood were not constant. The Poisson′s ratio of the bamboo plywood decreased nonlinearly with the load increase that Poisson′s ratio decreased markedly when the load was less than 1kN,and decreased gently when more than 1kN.The tensile elastic modulus of the bamboo plywood also increased nonlinearly with the load increase that the tensile modulus of elasticity increased drastically when the load was less than 800N,and increased less when exceeded 800N. In the process of loading,the tensile deformation、the tensile stress and strain all increased linearly with the load increase,and the tensile stress and strain both were linearly relevant to tensile deformation.
Authors: Xiao Zhang, Jian Zheng, Wei Peng, Zhi Xu Gu
Abstract: This paper reviews domestic and foreign study result of the calculation method and variation of solid propellant and other viscoelastic material ratio of solid propellant, the viscoelastic material's Poisson's ratio as well as Poisson's ratio's influence on the structure performance of solid propellant.
Authors: Jeong Eun Kim, Wan Shin Park, Seong Ho Cho, Do Gyeum Kim, Jea Myoung Noh
Abstract: Fly ash has been used in the construction of nuclear power plant faced with marine environment. The influence of supplementary fly ash on the mechanical properties of high performance concrete (HPC) has been investigated in this study. Selected test variables were fly ash replacement ratio with four levels (0 %, 10%, 20% and 30%) and curing days (28 days, 56 days and 91 days). This paper outlines an experimental study on compressive strength, splitting tensile strength, modulus of elasticity and Poissons ratio of HPC using ordinary Portland cement and fly ash.
Authors: Fabrice Pierron, Sam A. McDonald, D. Hollis, Philip J. Withers, A. Alderson
Abstract: This paper deals with the use of X-ray tomography and Digital Volume Correlation in order to study the mechanical behaviour of a low density polymeric auxetic foam. First, the metrological performances of the procedure are assessed using rigid body translation. Then, tensile test results are analyzed for two load steps and comments on the deformation process of the foam are given with a specific view to Poisson’s effect.
Authors: Xian Gui Ni, Z. Zhang, Y. Wang, Xiu Xi Wang
Abstract: Three armchair single-walled carbon nanotubes (SWCNTs) (7, 7), (12, 12), (17, 17) and three zigzag SWCNTs (12, 0), (16, 0), (20, 0) are investigated in this paper, using the molecular dynamic (MD) method with the second-generation Tersoff-Brenner (TB) potential. The Poisson’s ratio of these nanotubes under tensile and compressive loading is obtained. The effect of the strain and size on the Poisson’s ratio of nanotubes is analyzed systematically, from the viewpoints of the structure and the averaged atomic potential energy of nanotubes. The results show that the Poisson’s ratio of nanotubes decreases as the strain increases. The Poisson’s ratios of nanotubes of larger chiral angle decrease more quickly. For nanotubes of the same chiral angle, the larger the diameters of nanotubes are, the larger their Poisson’s ratios become. Moreover, the Poisson’s ratios of nanotubes of larger diameter are more approaching.
Authors: V.N. Belomestnykh, E.G. Soboleva
Abstract: Anisotropic and isotropic Poisson’s ratios for cuprum oxide are studied basing on the known experimental values of rigidity constants of Cu2O monocrystals within the temperature interval 4.2...873 K. The Poisson’s ratios of the given crystal are studied under the change of external conditions within the given intervals.
Authors: Yan Ru Li, Hai Bo Jiang, Wan Shan Chen
Abstract: This paper proposed a calculation model of transverse Poisson's ratio of continuous fiber reinforced composite, in which the fibers are centrally arranged in a representative volume element. According to the equivalent strain rule of matrix and fiber in fiber direction, the formula of transverse Poisson's ratio was deduced by mathematical method, which shows that the transverse Poisson's ratio of the composite material is associated with the Poisson's ratios and the elastic modulus of fiber and matrix. It was shown by an example that the transverse Poisson's ratio of composite was less than the weighted average number of the Poisson's ratios of fiber and matrix , even less than the matrix Poisson's ratio in a large range. The minimum value indicates that the fibers obviously resist longitudinal deformation under the transverse force.
Authors: Josep Antonio Benito, Jordi Jorba, Antoni Roca
Authors: Marko Peura, Seppo Andersson, Ari Salmi, Timo Karppinen, Mika Torkkeli, Edward Hæggström, Ritva Serimaa
Abstract: The excellent mechanical properties of wood arise from its cellular and cell wall structure. X-ray scattering, ultrasound, and mechanical testing is combined to study the effects of strain on crystalline cellulose in wood. Results for dry and re-moistened softwood samples are reviewed and new results are presented for native, never-dried samples of Silver birch. When softwood is stretched parallel to the cell axis, the mean microfibril angle diminishes significantly in compression wood, but only slightly in clear wood. The cellulose chains in the crystallites elongate and their distance diminishes. In the never-dried Silver birch samples, axial strain caused the mode of the microfibril angle distribution to slightly decrease from the initial value of 14 degrees to 12 degrees. Unlike in softwood, in never-dried birch crystalline cellulose showed auxetic tensile behaviour. The distance of the chains increased and the X-ray Poisson ratio νca was negative, -0.3 ± 0.2. Dehydration of never-dried Silver birch caused no difference to the microfibril angle distribution.
Authors: Qusai Hatem Jebur, Philip Harrrison, Zao Yang Guo, Gerlind Schubert, Vincent Navez
Abstract: This paper describes uniaxial compression tests on a melt-extruded closed-cell Low-Density Polyethylene (LDPE) foam. The stress-strain response shows the mechanical behaviour of the foam is predominantly transversely isotropic viscoelastic and compressible. Images analysis is used to estimate the Poisson’s ratio under large strains. When the deformation is less than 5 percent, the kinematics and mechanical response of the polymer foam can be well-described by a linear compressible transversely isotropic elastic model. For large strain, a method of manipulating experimental data obtained from testing in the principal and transverse directions (stress vs strain and Poisson’s ratio) in order to estimate the uniaxial compression response of the foam at any arbitrary orientation is proposed. An isotropic compressible hyperfoam model is then used to implement this behaviour in a finite element code.
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