Multi-scale simulations of the contact mechanics of lubricated, rough surfaces

润滑粗糙表面接触力学的多尺度模拟

• 批准号: 340916-2006
• 负责人: Mueser, Martin
• 金额: $ 2.72万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Collaborative Research and Development Grants
• 财政年份: 2008
• 资助国家: 加拿大
• 起止时间: 2008-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=399221
• 关键词: Multi; scale; simulations; contact; mechanics

The applicants at UWO and General Motors of Canada (GM) will carry out collaborative research related to wear in aluminum engines.  Wear limits the life span of mechanical devices with moving parts such as cylinders and pistons in car engines.  Understanding and controlling wear is of obvious economic interest to companies and consumers alike. However, surprisingly little is known about the microscopic origins of wear.  One reason for this deficiency is that the distribution of local pressures in engineering contacts is difficult to predict.  Even highly polished surfaces turn out to be very rugged when looked at with sufficiently high resolution.  To complicate things, it is difficult to assess the behaviour of the lubricant immersed between the moving parts.  For example, it is very difficult to predict whether the lubricant gets squeezed out when two asperities (little bumps) of two opposed surfaces collide or whether it solidifies in response to the immense local pressures in these microscopic points of contact.  Things become even more complicated for modern, fuel-efficient, aluminium-based engines.  Not only are the surfaces rugged, but in order to harden the materials, little silicon crystals are embedded into the aluminium matrix.  These crystalites stick out of the surfaces and supposedly carry most of the load in sliding contacts. Unfortunately, very little is known as yet about the true pressure distribution. Conventional methods to describe contact mechanics break down for these systems.  By combining atomistic computation techniques with more conventional methods, we intend to assess what factors lead to favourable mechanical behavior. More specifically, the simulated stress distribution on a rough Al-Si surface promises to give valuable guidelines as to how one might want to optimize the geometry of surfaces, which lubricant properties are preferential (strong or weak pressure dependence of viscosity) and whether one would want good stick conditions of a lubricant on the aluminum and/or on the silicon-dominated grains.  This information can then be used to design aluminum engines for minimal sliding friction and high wear resistance.

UWO和加拿大通用汽车公司（GM）的申请人将开展与铝发动机磨损相关的合作研究。磨损限制了汽车发动机中气缸和活塞等运动部件的机械设备的寿命。了解和控制磨损对公司和消费者都有明显的经济利益。然而，令人惊讶的是，人们对磨损的微观根源知之甚少。造成这一缺陷的原因之一是，工程接触中局部压力的分布难以预测。即使是高度抛光的表面，当用足够高的分辨率观察时，也会变得非常粗糙。更复杂的是，很难评估浸入运动部件之间的润滑剂的行为。例如，很难预测当两个微凸体两个相对表面的碰撞（小凸起），或者它是否会在这些微观接触点的巨大局部压力下固化。对于现代的省油铝基发动机来说，事情变得更加复杂。不仅表面粗糙，而且为了硬化材料，少量的硅晶体嵌入到铝基体中。2这些晶体伸出表面，应该承担滑动接触中的大部分载荷。不幸的是，我们对真实的压力分布还知之甚少。传统的方法来描述这些系统的接触力学break. By结合原子计算技术与更传统的方法，我们打算评估什么因素导致有利的机械行为。更具体地说，粗糙Al-Si表面上的模拟应力分布有望为如何优化表面几何形状提供有价值的指导，哪些润滑剂性能是优先的（粘度的强或弱压力依赖性）以及是否需要润滑剂在铝和/或硅上的良好粘附条件。这些信息可用于设计铝发动机，以实现最小的滑动摩擦和高耐磨性。