共查询到20条相似文献,搜索用时 375 毫秒
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考虑地基-结构-散粒体相互作用时贮仓结构的静、动力研究[Ⅱ]--有限元分析 总被引:1,自引:0,他引:1
对贮仓结构的静、动力问题进行了系统的分析计算:考虑到地基—结构—散粒体间的相互作用,引入新的计算模式,对不同地基上的贮仓结构模型进行了系统的有限元静、动力分析计算,并与作者所完成的试验结果进行了比较。结果表明,所提出的计算模式及有限元计算模型是正确的。 相似文献
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以筒仓模型结构为例,考虑到散粒体-结构-地基的相互作用,对弹性地基上筒仓内的散粒体的不同计算模型进行了多种工况、系统的有限元动力分析计算。通过与筒仓模型动力实验结果进行了比较,得出结论:在对地基施以水平激励时,弹性地基上筒仓的动力响应大于刚性地基上筒仓的动力响应,散粒体与仓壁的相对运动对筒仓结构有减振作用。 相似文献
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本文提出了弹性-粘弹性复合结构动力特性和动力响应的数值计算方法。为了给动力特性分析提供初值,定义了复合结构的“对偶保守结构”概念。用“对偶保守结构”的实模态参数确定复特征值初值,逐个迭代计算复合结构的复模态参数,同时还给出了两种数值方法计算复合结构的时域响应,可适应于一般载荷的响应计算,最后给出了部分计算与实验结果,并进行了比较,结果令人满意。 相似文献
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本文应用边界单元法对基础振动的动力响应进行了数值求解。结构的弹性动力微分方程在通过Laplace积分变换后,可以得到弹性动力的基本边界积分方程。然后在变换空间内划分边界单元进行数值求解。最后通过Laplace的数值逆变换求得时间域内的动力响应值。文中对刚性的动力基础,在简谐荷载的作用下,对于不同频率、不同压缩层厚度和基础埋深等动力响应进行了计算与探讨。 相似文献
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随机结构动力分析的递归聚食缩算法 总被引:2,自引:0,他引:2
首先介绍一种新型的随机结构动力分析方法,扩阶系统方法,然后建议了用于扩阶系统动力分析的递归聚缩算法,在不降低计算精度的条件下,递归聚缩算法可以大幅度地提高随机结构动力反应分析的速度,使关于扩阶系统动力分析的计算速度接近于相应的确定性结构系统的计算速度,从而,为随机结构分析的扩阶系统方法进入到实用了阶段铺平了道路。 相似文献
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首先介绍了一种新型的随机结构动力分析方法:扩阶系统方法,然后建议了用于扩阶系统动力分析的速归聚缩算法.在不降低计算精度的条件下,递归聚缩算法可以大幅度地提高随机结构动力反应分析的速度,使关于扩阶系统动力分析的计算速度接近于相应的确定性结构系统的计算速度.从而,为随机结构分析的扩阶系统方法进入到实用阶段铺平了道路. 相似文献
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《International Journal of Solids and Structures》2005,42(2):455-476
The present work addresses the problem of calculation of the macroscopic effective elastic properties of composites containing transversely isotropic phases. As a first step, the contribution of a single inhomogeneity to the effective elastic properties is quantified. Relevant stiffness and compliance contribution tensors are derived for spheroidal inhomogeneities. The limiting cases of spherical, penny-shaped and cylindrical shapes are discussed in detail. The property contribution tensors are used to derive the effective elastic moduli of composite materials formed by transversely isotropic phases in two approximations: non-interaction approximation and effective field method. The results are compared with elastic moduli of quasi-random composites. 相似文献
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The calculation of the effective elastic moduli of inhomogeneous solids, which connect the stresses and strains averaged for the material, is accompanied by certain mathematical difficulties owing to correlation relationships of arbitrary orders. Neglect of correlation relationships leads to average elastic moduli, where averaging according to Voigt and Reuss establishes boundaries containing the effective elastic moduli [1]. Approximate values of the latter can be found by taking into account the correlation relationships of the second order in both calculation schemes [2, 3]. Another method of evaluating the true moduli consists of narrowing the boundaries of Voigt and Reuss on the basis of model representations [4-6]. The approximate effective elastic moduli for a series of polycrystals with various common-angle values are presented in [7]. An analysis of the effect of the correlation relationships between the grains of a mechanical mixture of isotropic components on the effective elastic moduli is carried out in [8], although in all the papers just mentioned the use of correlative corrections to narrow the range of elastic moduli is not investigated. Below it is shown that the calculation of the correlation corrections in the second approximation allows the range for the effective moduli to be narrowed. 相似文献
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采用弹性理论研究了拉压不同弹性模量薄板上圆孔的孔边应力集中问题.采用广义虎克定律推导出了拉压不同弹性模量薄板上圆孔边的应力平衡方程,并联合利用应力函数及边界条件得到了拉压不同弹性模量薄板上圆孔边的应力表达式.算例分析表明,当薄板材料的拉压弹性模量相差较大时,采用经典弹性理论研究薄板上圆孔的孔边应力是不合适的,当经典弹性理论与拉压不同弹性模量弹性理论的计算结果间的差别超过工程允许误差5%时,应该采用拉压不同弹性模量弹性理论进行计算. 相似文献
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N. Kamiya 《基于设计的结构力学与机械力学》2013,41(3):317-329
Abstract Some composite materials and high-polymers are known to behave differently in simple tension and compression under static loads. The present paper is concerned with a method of analysis of the bending of bimodulus elastic plates employing Ambartsumyan-Khachatryan's model for isotropic bimodulus materials. This problem may be reduced to the conventional problem of minimizing the potential energy of the plate as a whole. A simply supported thin square plate subjected to lateral load is analyzed numerically by a simplex method. Results of the calculation show that the effect of the difference between the tensile and compressive elastic moduli on the deformation of the plate may be substantial 相似文献
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In this work we consider a cylindrical structure composed of a nonlinear core (inhomogeneity) surrounded by a different nonlinear shell (matrix). We elaborate a technique for determining its linear elastic moduli (second order elastic constants) and the nonlinear elastic moduli, which are called Landau coefficients (third order elastic constants). Firstly, we develop a nonlinear perturbation method which is able to turn the initial nonlinear elastic problem into a couple of linear problems. Then, we prove that only the solution of the first linear problem is necessary to calculate the linear and nonlinear effective properties of the heterogeneous structure. The following step consists in the exact solution of such a linear problem by means of the complex elastic potentials. As result we obtain the exact closed forms for the linear and nonlinear effective elastic moduli, which are valid for any volume fraction of the core embedded in the external shell. 相似文献
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Israel Cohen 《Journal of the mechanics and physics of solids》2004,52(9):2167-2183
Recently, Cohen and Bergman (Phys. Rev. B 68 (2003a) 24104) applied the method of elastostatic resonances to the three-dimensional problem of nonoverlapping spherical isotropic inclusions arranged in a cubic array in order to calculate the effective elastic moduli. The leading order in this systematic perturbation expansion, which is related to the Clausius-Mossotti approximation of electrostatics, was obtained in the form of simple algebraic expressions for the elastic moduli. Explicit expressions were derived for the case of a simple cubic array of spheres, and comparison was made with some accurate results. Here, we present explicit expressions for the effective elastic moduli of base-centered and face-centered cubic arrays as well, and make a comparison with other estimates and with accurate numerical results. The simple algebraic expressions provide accurate results at low volume fractions of the inclusions and are good estimates at moderate volume fractions even when the contrast is high. 相似文献
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《Wave Motion》2015
The self-consistent method of averaging elastic moduli to define the effective medium of a polycrystal is used to investigate the dynamic problem of wave propagation. An alternative covariance tensor describing the elastic moduli fluctuations of the polycrystal containing self-consistent elastic properties is derived and found to be significantly smaller than the covariance tensor formed through traditional Voigt averaging. Attenuation curves are generated using the self-consistent elastic moduli and covariance tensors and these results are compared with previous Voigt-averaged estimates. The second-order polycrystalline dispersion relation for the self-consistent scheme is found for cases of low and high crystallite anisotropy. The attenuation coefficients and dispersion relations derived through the self-consistent scheme are considerably different than previous estimates. Experimentally measured longitudinal attenuation coefficients support the use of the self-consistent scheme for estimation of attenuation. 相似文献
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David L. Clements 《Journal of Elasticity》2011,103(2):137-152
This paper employs a displacement based method to examine an antiplane crack problem for an inhomogeneous elastic material
in which the elastic moduli vary continuously with the spatial coordinates. Expressions for the crack tip stress intensity
factors and the crack displacement are obtained in terms of Chebyshev polynomials. Numerical results are obtained for some
particular inhomogeneous elastic materials. 相似文献
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《International Journal of Solids and Structures》2005,42(2):393-408
The problem to determine the effective elastic moduli and velocities of elastic wave propagation in transversely isotropic solid containing aligned spheroidal inhomogeneities (solid grains, vugs and micro-cracks) has been solved using the self-consistent scheme known as effective medium approximation (EMA). Since a solution of so-called one-particle problem is a base for each self-consistent method, we solved this problem as a first step for spheroidal inhomogeneity in a transversely isotropic medium. In contrast to the known solution of this problem by Lin and Mura we obtained the expressions for the strain field inside inclusion in the explicit form (without quadratures). The obtained solution was used then in the symmetric variant of the EMA where each component of the system was considered as spheroid with its own aspect ratio. This approach was applied to simulate the properties of the rocks containing isolated pores and micro-cracks. For connected fluid-filled pores we used the anisotropic variant of the Gassmann theory. The results of the calculations, obtained for the effective elastic moduli, have been compared with the experimental data and theoretical simulations of the other authors. Unlike many other rock mechanics theories, EMA approximation gives correct elastic moduli values even in the nondilute concentration of inhomogeneities. The comparison of the experimental data for oriented crack system with the EMA predictions indicates their good correspondence. 相似文献
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《应用数学和力学(英文版)》2017,(1)
Reservoir porous rocks usually consist of more than two types of matrix materials,forming a randomly heterogeneous material.The determination of the bulk modulus of such a medium is critical to the elastic wave dispersion and attenuation.The elastic moduli for a simple matrix-inclusion model are theoretically analyzed.Most of the efforts assume a uniform inclusion concentration throughout the whole single-material matrix.However,the assumption is too strict in real-world rocks.A model is developed to estimate the moduli of a heterogeneous bimaterial skeleton,i.e.,the host matrix and the patchy matrix.The elastic moduli,density,and permeability of the patchy matrix differ from those of the surrounding host matrix material.Both the matrices contain dispersed particle inclusions with different concentrations.By setting the elastic constant and density of the particles to be zero,a double-porosity medium is obtained.The bulk moduli for the whole system are derived with a multi-level effective modulus method based on Hashin's work.The proposed model improves the elastic modulus calculation of reservoir rocks,and is used to predict the kerogen content based on the wave velocity measured in laboratory.The results show pretty good consistency between the inversed total organic carbon and the measured total organic carbon for two sets of rock samples. 相似文献