论文标题
鉴定非本地连续性晶格样材料
Identification of non-local continua for lattice-like materials
论文作者
论文摘要
该论文的重点是在节点处的晶格样材料的动态均匀化,以获得能量一致的模型,从而提供了对离散系统声学行为的准确描述。晶格的运动方程是根据旨在识别等效非本地连续模型的整体差异和梯度类型的等效非本地连续模型进行转换的,后者是通过标准或增强的持续化获得的。运动差方程的双边z传输与转换后的傅立叶空间中等效连续体的总体差异方程相匹配,后者具有与lagrangian相同的频段结构。首先,结果表明,通过泰勒多项式的内核的近似导致具有非本地本构术语的高阶连续性的差分场方程。从这种方法得出的场方程对应于通过所谓的标准持续化获得的场方程。然而,由于差异问题的差异问题是由于高阶连续体的势能密度的非阳性确定性。通过适当的映射将傅立叶空间中转换后的宏位分位与新的辅助正规化连续宏位移区域中的新辅助宏位置相关联,已经确定了能量一致的等效连续图。具体而言,这里引入的映射在第一个布里远区域的边缘具有零。整体分化的统计方程和相应的差异方程通过增强的持续化重新构建,该持续化的特征是具有能量一致的微分方程。积分分化方程的本构和惯性核在第一个布里渊区的边缘显示出极性奇异性。
The paper is focused on the dynamic homogenization of lattice-like materials with lumped mass at the nodes to obtain energetically consistent models providing accurate descriptions of the acoustic behavior of the discrete system. The equation of motion of the lattice is transformed according to a unitary approach aimed to identify equivalent non-local continuum models of integral-differential and gradient type, the latter obtained through standard or enhanced continualization. The bilateral Z-transform of the difference equation of motion is matched to the governing integral-differential equation of the equivalent continuum in the transformed Fourier space, which has the same frequency band structure as the Lagrangian one. Firstly, it is shown that the approximation of the kernels via Taylor polynomials leads to the differential field equations of higher order continua endowed with non-local constitutive terms. The field equations derived from such approach corresponds to the ones obtained through the so called standard continualization. However, the differential problem turns out to be ill-posed because the non-positive definiteness of the potential energy density of the higher order continuum. Energetically consistent equivalent continua have been identified through a proper mapping correlating the transformed macro-displacements in the Fourier space with a new auxiliary regularizing continuum macro-displacement field in the same space. Specifically, the mapping here introduced has zeros at the edge of the first Brillouin zone. The integral-differential governing equation and the corresponding differential one has been reformulated through an enhanced continualization that is characterized by energetically consistent differential equations. The constitutive and inertial kernels of the integral-differential equation exhibit polar singularities at the edge of the first Brillouin zone.