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细观力学的一个主要研究内容是求复合材料的等效弹性性能.常见的细观力学模型解析公式一般假定基体各向同性且只存在纤维和基体两相材料,实际复合材料的基体和纤维之间往往存在一个横观各向同性的界面相,该三相复合材料的等效性能可由两个两相复合材料性能的组合得到,这就需要求出横观各向同性基体复合材料的等效弹性常数.该文基于两相同心圆柱模型,首先导出了横观各向同性基体内应力与增强纤维内应力之间桥联矩阵的解析公式,与基于数值积分Eshelby张量得到的Mori-Tanaka桥联矩阵相符,再进一步获得了横观各向同性基体复合材料的5个弹性常数显式表达式.文中还给出了扩展的桥联模型显式公式.选用适当的桥联参数,两种模型所得结果十分接近. 相似文献
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在非线性各向同性弹性体张量形式的本构方程基础上,仅考虑温度初值和增值,按照表示定理,补充考虑温度影响的完备项,建立了非线性各向同性弹性材料完备的多项式形式的热应力本构方程和应变能函数.作为应用举例,利用MATLAB软件,将本构方程与现有文献中高温金属材料单向拉伸和压缩情况下弹性阶段的实验数据进行了拟合,结果表明实验值与所提出的理论模型的结果显示了良好的一致性. 相似文献
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本文从横观各向同性体弹性力学位移形式的基本方程出发,考虑板面承受横向荷载,建立了横观各向同性板弯曲的弹性理论.并由此建立了一个在板的每边能满足三个边界条件的弹性改进理论和一种新的厚板理论.文中求得了周边简支多边形板的弹性改进理论解,数值结果与三维弹性理论精确解的结果非常接近.新的厚板理论和以往的中厚板理论的系统比较表明,我们提出的厚板理论最靠近弹性理论的结果. 相似文献
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横观各向同性弹性层点力解 总被引:3,自引:0,他引:3
本文根据弹性层状结构的传递矩阵法思想,由横观各向同性弹性力学基本方程,导出了含应力和位移两类变量的混合方程,利用Fourier变换和文献[7]的位移函数通解,以及计算机代数软件,得到了横观各向同性层的点力解,这个点力解可直接退化到各同性情形的解. 相似文献
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横观各向同性多孔超弹性矩形板的单向拉伸 总被引:2,自引:0,他引:2
利用横观各向同性超弹性材料的广义neo-Hookean应变能函数研究了含有多个微孔的超弹性矩形板在单向拉伸作用下的有限变形和受力分析.给出了含有某种对称性分布的多个微孔的矩形板的变形模式,通过求解该变形模式满足的微分方程,将它用两个参数表示出来.可应用最小势能原理导出变分近似解,从而得到矩形板的变形和应力分布的解析解.分析了板中微孔的增长及微孔边缘应力的分布情况,讨论了板的各向异性程度及微孔的大小和孔间距离的影响,得到了单个、三个及五个微孔板中微孔的增长变形和孔边应力分布的一些基本规律规律,并进行了相互比较. 相似文献
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各向同性张量在构造各向同性弹性固体的本构方程时有着极其重要的作用.基于各向同性Descartes张量的表达式并结合超对称张量的性质,探讨了各向同性Descartes张量各标量之间的关系,进而得出了二到六阶各向同性超对称Descartes张量的一般表达式. 相似文献
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将Dui和Chen于2004年提出的求解对称各向同性张量函数导数的方法推广到一类满足可交换条件的非对称各向同性张量函数情况,此类函数比以往研究的更具一般性.在有3个不同特征根时,由可交换性引进张量函数相对应的标量函数,进而求得此类非对称各向同性张量函数及其导数的不变表示形式.在2或3重特征根时,利用求极限的办法给出此类张量函数及其导数的表示形式. 相似文献
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Z. A. Yanson 《Journal of Mathematical Sciences》1999,96(4):3434-3446
The asymptotics of high-frequency Love waves, which are analogous to transverse surface SH waves, is considered for a special type of anisotropy (transverse isotropy) of elastic media. The wave field is represented as a sum of the space-time (ST) caustic expansion and two additional ST ray series for faster (relative to the transverse surface wave) body waves, decaying exponentially with depth. Near the surface, the coefficients of the ST caustic and ray series, as well as the eikonals of waves, are determined in the form of expansions in a small parameter, which characterizes the proximity of the caustic of the ray field to the surface. With regard for the specific structure of the elasticity tensor of a transversely isotropic medium, the surface is treated as a plane. Interrelations between the parameters of elasticity, which are consistent with the conditions of the positivity of the elastic deformation energy and provide for the origination of the surface waves considered, are obtained.Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 239, 1997, pp. 243–262.This work was supported by the Russian Foundation for Basic Research under grant No. 96-01-00666. 相似文献
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The representation of the displacement gradient of an isotropic elastic body is analyzed. It is shown on the basis of a single controlling inequality and a polar expansion of the Piola tensor that such representation has generally four branches. The mechanical meaning and the nature of that ambiguity is explained. It is established that when the angles of turn of material fibers are not excessively large, only one of the four branches is obtained. Particular cases in which the nature of ambiguity is more complex are investigated. It is noted that in many practical problems the representation of the displacement gradient by the Piola stress tensor is unambiguous.The considered problem is associated with the variational principle of complementary energy in the nonlinear theory of elasticity, where the statistically feasible fields of the asymmetric Piola stress tensor is varied [1], A method was proposed there for expressing the displacement gradient in terms of the Piola stress tensor for an isotropic elastic body. Later the concept of complementary energy and the representation of the strain gradient in terms of the Piola stress tensor were considered in [2, 3]. Examples of the use of the complementary energy concept are given in [2] and the case of an anisotropic body is considered in [3], These investigations disclosed that the considered representation of the strain tensor leads to ambiguity, but the character and nature of the ambiguity were not fully investigated. 相似文献
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By considering continuum interface problems like e.g. the modeling of composites, the possible loss of well posedness of the resulting Boundary Value Problem has to be considered, dependent on the choice of material laws in the bulk and in the interface. In this contribution, the problem is discussed for a bulk material connected to a rigid substrate by an interface layer. The isotropic bulk material is linear elastic while for the interface elasticity and elasticity with damage is investigated. A complex surface acoustic tensor is introduced by applying a decaying surface wave ansatz to the incremental boundary value problem. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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The main propose of this paper is devoted to studying the solvability of the generalized order tensor complementarity problem. We define two problems: the generalized order tensor complementarity problem and the vertical tensor complementarity problem and show that the former is equivalent to the latter. Using the degree theory, we present a comprehensive analysis of existence, uniqueness and stability of the solution set of a given generalized order tensor complementarity problem. 相似文献
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Matrix logarithmic norm is an important quantity, which characterize the stability of linear dynamical systems. We propose the logarithmic norms for tensors and tensor pairs, and extend some classical results from the matrix case. Moreover, the explicit forms of several tensor logarithmic norms and semi‐norms are also derived. Employing the tensor logarithmic norms, we bound the real parts of all the eigenvalues of a complex tensor and study the stability of a class of nonlinear dynamical systems. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
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We derive a representation formula for the topological gradient with respect to arbitrary quadratic yield functionals and anisotropic elastic materials, thus laying the theoretical foundations for topological sensitivity analysis in lightweight design. For compliance, minimization involving general anisotropic materials and ellipsoidal perturbations, we give a closed formula for the topological gradient, enabling topology optimization of integrated designs involving several reinforced materials. If the materials are transversely isotropic and the perturbations are spheriodal, we even obtain an analytical formula. For general anisotropy, recent advances in the computation of Eshelby's tensor enable rapid numerical computation of the topological gradient. Restricting to isotropic materials and spheroidal inclusions, we obtain an analytical formula for minimizing isotropic yield functionals with applications to microscale‐scale sensitivity analysis of fiber reinforced composites or reinforcing analysis of brittle materials. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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黄勇 《数学的实践与认识》2008,38(1):169-176
张量分析是现代数学物理学的基础工具.从广义相对论开始,到规范场论,以至后来的弦理论,这些理论的建立都是因为有了张量分析.张量分析所提供的对曲线坐标系的微分方法,真正实现了非欧几何从概念到演算的革命,而所有这一切都是以张量概念的产生为基础的.因此,着重分析从1841年到1913年张量概念的形成与发展,在原始文献中寻找它的历史线索,并考证″tensor″一词的提出者. 相似文献