Simulation of Dissipation in Solids

主要研究者姓名，机构：Adnan Akay，Carnegie Mellon大学提案编号提案标题：固体中耗散的模拟项目摘要本项目涉及固体中耗散的建模和模拟。虽然常见的耗散形式如内阻尼和接触阻尼在动力学中具有非常重要的作用，但耗散仍然被视为一种物理现象，没有基于第一原理的描述。 固体中的耗散通常描述动能转化为热，例如，声波通过固体激发其原子并提高其能级。在假设原子处于热平衡状态下，原子振荡所增加的动能定义了固体的热容。 固体中耗散的模拟涉及到一个三维晶格的振荡器，这些振荡器代表用弹簧相互连接的原子。弹簧代表原子间非线性势产生的位移相关力。 具体的研究任务，以实现这一目标开始与一维阵列的非线性连接的振荡器调查数值的不可逆性和均分的条件。然后，模拟将扩展到非理想晶格，包括杂质来描述真实的固体，以研究它们在波数（和频率）转换中的作用。这项工作的一个重要方面将是确定下限的大小的模拟，以正确地描述耗散在固体和确定手段，以量化固体的耗散特性。拟议中的调查也将有助于澄清模糊阻尼固有的理论要求，把它们放在一个更基本的立足点，关于能量均分和不可逆吸收的能量。

PI's Name, Institution : Adnan Akay, Carnegie Mellon UniversityProposal NumberProposal Title: Simulation of Dissipation in SolidsProject Abstract This project concerns modeling and simulating dissipation in solids. Although common forms of dissipation such as internal damping and contact damping have a very important role in dynamics, dissipation is still treated as an empiricalphenomenon without a description based on first principles. Dissipation in solids often describes conversion of kinetic energy to heat as in, for example, a sound wave passing through a solid exciting its atoms, and raising their energy level. The increased kinetic energy of the oscillations of atoms define the heat capacity of a solid with the assumption that they are inthermal equilibrium. Simulation of dissipation in a solid involves a 3-D lattice of oscillators that represent atoms connected to each other with springs. Springs represent displacement-dependent forces thatresult from the nonlinear potential between the atoms. The specific research tasks to accomplish this goal begin with a one-dimensional array of nonlinearly connected oscillators to investigate numerically the conditions of irreversibility and equipartitioning. The simulations will then be extended to nonideal lattices that include impurities to describe real solids to investigate their role in wavenumber (and frequency)conversion. An important aspect of this effort will be to determine the lower limit of the size of simulations to correctlydescribe dissipation in a solid and determine means to quantify dissipation characteristics of solids. The proposed investigation will also help clarify the theoretical requirements inherent in fuzzy damping by putting them on a more fundamental footing regarding energy equipartition and irreversible absorption of energy.