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61.
Upper-bound estimates and supposedly exact numerical results are obtained for the limit loads associated with cylindrical cells containing voids and subjected to boundary conditions that are consistent with post-localization kinematics in porous plastic solids. When supplemented with evolution equations for the microstructural variables, the results can be used in the modeling of void coalescence by internal necking in ductile materials. 相似文献
62.
Compression fracture in carbon fiber reinforced plastics (CFRP) involves multiple physical mechanisms operating at multiple scales ranging from angströms to cms and beyond. First, at the macro/meso-scale, combined effects of modal imperfections, transverse shear/normal deformation along with the non-linear hypo-elastic transverse shear (GTT) material property on the emergence of interlaminar shear crippling type instability modes, related to the localization (onset of deformation softening), delocalization (onset of deformation hardening) and propagation of mode II compression fracture/damage, in thick imperfect cross-ply very long cylindrical shells under applied hydrostatic pressure, are investigated. The primary accomplishment is the (hitherto unavailable) computation of the layer-wise mode II stress intensity factor, energy release rate and kink crack band-width, under hydrostatic compression, from a non-linear finite element analysis (FEA), using Maxwell’s construction and Griffith׳s energy balance approach. Numerical results include the effects of hypoelastic (GTT only) material property, on localization and delocalization leading to compression fracture.At the micro-scale, a novel three-dimensional eigenfunction expansion technique, based in part on separation of the cylinder length-variable and partly utilizing a modified Frobenius type series expansion in conjunction with an affine transformation to compute the local stress singularity, in the vicinity of a kinked-fiber/matrix trimaterial junction front. Such computed stress singularities represent a measure of the degree of inherent flaw sensitivity of unidirectional CFRP under compression. Finally, dislocation glide in graphite crystallites plays a dominant role in kink band nucleation and propagation at the nano-meter scale. 相似文献
63.
F. Schmidt 《International Journal of Non》2010,45(9):866-875
This paper deals with energy transfer from initial one degree of freedom system including non-smooth terms of friction (Saint-Venant) type to an auxiliary mass via an adapted non-linear coupling. We describe design of auxiliary degree of freedom and non-linear smooth coupling to the initial one degree of freedom system. First the auxiliary system is designed as if the initial one degree of freedom system was simply elastic. Then we study numerically the transfer for the non-smooth system in the cases of free transient oscillations or forced oscillations under periodic external forcing. Efficiency of energy pumping is discussed. 相似文献
64.
采用De Giorgi迭代技巧,给出m-拉普拉斯型抛物方程解的局部化新证明,并得到一些先验估计。 相似文献
65.
YUAN Hongjun 《数学年刊B辑(英文版)》2001,22(3):361-380
61. IntroductionAs well knoWn, the solutionS of semilinear Parabolic equations at = An -- ac, 0 < q < 1have the ISS (the thetantaneous shrinking of the support) ~erty (see 11--5]).Such PrOPerty is d~d as follows.Defiallion 1.1. A hoction u E La(Q) is sold to haw the ISS p~rty, ijjor augr > 0, there hots a POsiboe n~ber R = R(T) such thatu(z, t) = 0for a. e. (z,t) e (R" \ Ba) x (T, co), tDhere AN is the N-dimensional Euclidean space,and Q = AN X (0, co).UP to the preseDt, there… 相似文献
66.
Viktor Hlukhyy Nataliya Chumalo Vasyl' Zaremba Thomas F Fässler Prof. Dr. 《无机化学与普通化学杂志》2008,634(8):1249-1255
The intermetallic germanides CaNiGe and MgCoGe have been synthesized from the elements in sealed tantalum tubes in a high‐frequency furnace. The compounds were investigated by X‐ray diffractions both on powders and single crystals: CeFeSi structure type, P4/nmm, a = 4.19341(3), c = 6.6264(1) Å, wR2 = 0.030, 124 F2 values, 10 variable parameters for CaNiGe and a = 3.8960(4), b = 6.1929(11) Å, wR2 = 0.048, 104 F2 values, 10 variable parameters for MgCoGe. In CaNiGe and MgCoGe the transition metal and germanium atoms build [TGe] layers (T = Ni, Co), which are separated by the calcium and magnesium atoms, respectively. The crystal structures of CaNiGe and MgCoGe as well as chemical bonding in CaNiGe and CaNi2Ge2 are discussed in terms of LMTO bond structure calculation and analysis using the Electron Localization Function (ELF). The Ge–Ge bond formation in polyanionic network of CaNi2Ge2 can formally be regarded as oxidative coupling product of layers of CaNiGe. 相似文献
67.
A periodic array of atomic sites, described within a tight binding formalism is shown to be capable of trapping electronic states as it grows in size and gets stubbed by an ‘atom’ or an ‘atomic’ clusters from a side in a deterministic way. We prescribe a method based on a real space renormalization group method, that unravels a subtle correlation between the positions of the side coupled atoms and the energy eigenvalues for which the incoming particle finally gets trapped. We discuss how, in such conditions, the periodic backbone gets transformed into an array of infinite quantum wells in the thermodynamic limit. We present a case here, where the wells have a hierarchically distribution of widths, hosting standing wave solutions in the thermodynamic limit. 相似文献
68.
X.Q. Huang R.W. Peng F. Qiu S.S. Jiang A. Hu 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,23(3):275-281
We study in this paper, with the context of a tight-binding on-side model, the electronic properties of one-dimensional random
lattices with correlated impurities. We show that, when symmetrical impurities
are inserted in a host chain of site energy and a constant hopping interaction V, diffusion will occur even when is random. We provide analytic expressions for the transmittance and confirm the theoretical results by a great deal of numerical
calculations. When = V, we find that the mean-square displacement (MSD) follows the law
m
2
∝t
β with β = 2.0 for = constant and β = 1.0 for = = random, respectively.
Received 15 January 2001 and Received in final form 30 April 2001 相似文献
69.
70.
Karl Lorensen 《代数通讯》2013,41(12):4345-4364