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71.
The mechanical behavior of rock under uniaxial tensile loading is different from that of rock under compressive loads. A micromechanics-based model was proposed for mesoscopic heterogeneous brittle rock undergoing irreversible changes of their microscopic structures due to microcrack growth. The complete stress-strain relation including linear elasticity, nonlinear hardening, rapid stress drop and strain softening was obtained. The influence of all microcracks with different sizes and orientations were introduced into the constitutive relation by using the probability density function describing the distribution of orientations and the probability density function describing the distribution of sizes. The influence of Weibull distribution describing the distribution of orientations and Rayleigh function describing the distribution of sizes on the constitutive relation were researched. Theoretical predictions have shown to be consistent with the experimental results. 相似文献
72.
The behavior of single-degree-of-freedom systems possessing quadratic and cubic nonlinearities subject to parametric excitation is investigated. Both fundamental and principal parametric resonances are considered. A global bifurcation diagram in the excitation amplitude and excitation frequency domain is presented showing different possible stable steady-state solutions (attractors). Fractal basin maps for fundamental and principal parametric resonances when three attractors coexist are presented in color. An enlargement of one region of the map for principal parametric resonance reveals a Cantor-like set of fractal boundaries. For some cases, both periodic and chaotic attractors coexist. 相似文献
73.
架设阶段悬索桥静力问题的随机有限元分析 总被引:5,自引:0,他引:5
架设阶段的悬索桥不仅具有显著的几何非线性行为,而且存在材料特性的变异。本文建立了以增量形式表达的非线性摄动法随机有限元列式,并编制了悬索桥静力分析程序SNAP。针对一座国内在建的悬索桥,计算了该桥在某一施工阶段考虑缆索弹性模量随机性时主梁跨中点位移的变化。结果表明,材料随机性的影响十分明显。 相似文献
74.
Structure of the constitutive relations for hereditarily elastic materials reinforced by hard fibers
R. A. Kayumov I. G. Teregulov 《Journal of Applied Mechanics and Technical Physics》2005,46(3):405-411
The problem of simplifying the nonlinear hereditary elasticity relations is considered for strongly anisotropic materials
such as fiber-reinforced composites. This is done using their property that the material stiffness is high along the reinforcement
and is low in the cross-sectional direction. The material is considered transversally isotropic. The simplification is performed
by analyzing asymptotic representations of creep relations. Relations of various degrees of accuracy for various types of
composites and stress states are obtained.
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Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 3, pp. 120–127, May–June, 2005. 相似文献
75.
A coupled map lattices with convective nonlinearity or, for short, Convective Coupled Map (CCM) is proposed in this paper
to simulate spatiotemporal chaos in fluid flows. It is found that the parameter region of spatiotemporal chaos can be determined
by the maximal Liapunov exponent of its complexity time series. This simple model implies a similar physical mechanism for
turbulence such that the route to spatiotemporal chaos in fluid flows can be envisaged.
The study is supported by “Nonlinear Sciences Project” from the State Science and Technology Commission of China. 相似文献
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79.
This paper deals with the initial boundary value problem for strongly damped semilinear wave equations with logarithmic nonlinearity in a bounded domain . We discuss the existence, uniqueness and polynomial or exponential energy decay estimates of global weak solutions under some appropriate conditions. Moreover, we derive the finite time blow up results of weak solutions, and give the lower and upper bounds for blow-up time by the combination of the concavity method, perturbation energy method and differential–integral inequality technique. 相似文献
80.
Gibbs samplers derived under different parametrizations of the target density can have radically different rates of convergence. In this article, we specify conditions under which reparametrization leaves the convergence rate of a Gibbs chain unchanged. An example illustrates how these results can be exploited in convergence rate analyses. 相似文献