Greens function molecular dynamics simulation of sliding, adhesive contacts

滑动、粘合接触的格林函数分子动力学模拟

• 批准号: 192177457
• 负责人: Professor Dr. Martin Müser
• 金额: --
• 依托单位: Leibniz-Institut für Neue Materialien gGmbH (INM)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2010
• 资助国家: 德国
• 起止时间: 2009-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/192177457?language=en
• 关键词: Greens; function; molecular; dynamics; simulation

This proposal evolves around the question: When does adhesion between solid bodies cause friction? From every day experience, we might be tempted to expect a large degree of correlation between these two properties. However, this is scarcely understandable from a microscopic view, since roughness (in the more precise jargon of physics: broken translational invariance) on both solids is a basic requirement for friction to occur. Roughness, however, counteracts adhesion and every surface is microscopically rough. The central goal of this proposal is to identify simple rules for a large class of surfaces that allow us to predict from a few (mainly, but not exclusively microscopic) parameters, if and how strongly (macroscopic) surfaces attract and what amount of adhesion-induced friction between the surfaces is unavoidable.Computer simulations shall be used to answer the just raised questions. They allow one to define all relevant quantities, such as the surface topographies, the elastic properties of the solids and their interactions, with mathematical precision. Since virtually all surfaces bear multi-scale roughness (in fact, they can be considered self-similar or fractal over several decades), the simulations must reflect a multitude of scales as well, which, in turn, necessitates efficient methods. Owing to significant progress in the recent past, criteria could be identified allowing one to predict with relatively simple rules when surfaces are sticky. However, in order to address the questions of 'how sticky?' and 'how much friction does adhesion induce?', the methods have to be much further advanced. Likewise, we see it as critical for a successful execution of the project to improve our understanding of the effect of temperature, waiting times (thermal aging), and the influence of the thickness of solid bodies on adhesion.A purely experimental analysis of the just raised question does not appear sensible at the moment, because it is technically not yet possible or unjustifiable expensive to measure sufficiently large surface topographies with the needed precision. In addition, only simulations allow one to vary all relevant parameters systematically and continuously. Experiments yet remain without any doubt indispensible for the validation of simulations. Colleagues outside the framework of this proposal agreed to conduct them.One goal of this proposal is to apply the newly gained insights and newly developed methods to optimize the geometry of adhesive systems (pick-up devices) of technological relevance. In this context, it might be worth mentioning that -- once all features are coded up -- exploring the effect of a single parameter on the device performance necessitates only one hour of manpower plus one day supercomputer time.

这个提议围绕着一个问题展开：什么时候固体之间的粘附会引起摩擦？从日常经验来看，我们可能会倾向于期望这两种属性之间存在很大程度的相关性。然而，从微观角度来看，这几乎是不可理解的，因为两种固体上的粗糙度（用更精确的物理术语来说：破碎的平移不变性）是发生摩擦的基本条件。然而，粗糙度抵消了附着力，每个表面都是微观粗糙的。本提案的中心目标是确定一大类表面的简单规则，使我们能够从几个（主要但不完全是微观的）参数中预测（宏观的）表面是否和有多强的吸引力，以及表面之间不可避免的粘附引起的摩擦的数量。计算机模拟可以回答刚才提出的问题。它们允许人们以数学精度定义所有相关的量，如表面形貌、固体的弹性特性及其相互作用。由于几乎所有的表面都承受着多尺度的粗糙度（事实上，在几十年的时间里，它们可以被认为是自相似的或分形的），模拟也必须反映大量的尺度，这反过来又需要有效的方法。由于最近取得的重大进展，可以确定标准，使人们能够用相对简单的规则预测表面何时具有粘性。然而，为了解决“粘性有多大？”和“粘附产生多少摩擦？”’，这些方法必须更加先进。同样，我们认为提高我们对温度、等待时间（热老化）的影响以及固体厚度对附着力的影响的理解对于项目的成功执行至关重要。对刚刚提出的问题进行纯粹的实验分析在目前看来是不明智的，因为以所需的精度测量足够大的表面地形在技术上还不可能或不合理地昂贵。此外，只有模拟才能系统地、连续地改变所有相关参数。毫无疑问，实验对于模拟的验证仍然是必不可少的。本提案框架之外的同事同意进行这些测试。本提案的一个目标是应用新获得的见解和新开发的方法来优化与技术相关的粘合剂系统（拾取装置）的几何形状。在这种情况下，值得一提的是，一旦所有功能都编码好，探索单个参数对设备性能的影响只需要一个小时的人力加上一天的超级计算机时间。