Influence of the surface geometry on the friction in adhesive contacts

接触体在黏着相互作用下的切向加载和运动是接触力学中最不为人所知的现象。与正常的粘接接触相反，即仅仅是接触的接近和脱离，没有普遍的，基于能量的方法来解决这个问题。相反，耗散力起着至关重要的作用。计划项目的主要目标是阐明粘接接触中摩擦力和能量耗散的微观和细观起源。在此基础上，应提出一种对黏着切向接触进行建模和仿真的概念，用数值程序实现并进行实验验证。我们的指导思想是，微观尺度上的粘附是无耗散的，只有由表面化学或地形的微观异质性引起的不稳定性才会导致能量耗散（以及相应的摩擦力）。虽然这个想法在摩擦物理学中并不新鲜（Prandtl-Tomlinson模型），但它尚未明确应用于切向粘接接触。为了实现这一目标，基于已经开发的模拟可逆粘附的方法，对异质接触进行理论研究。这将与系统的粘接切向接触实验研究相结合。对胶粘剂接触中耗散过程的良好的物理理解将引导在实际应用中控制胶粘剂相互作用的方法。特别是，形状、粗糙度、材料非均匀性和其他尚未确定的系统参数的影响将从理论上和实验上进行检验。

Tangential loading and movement of contacting bodies in the presence of adhesive interaction belongs to the least understood phenomena in contact mechanics. In contrast to normal adhesive contact, i.e. the mere approach and detachment of contacts, there is no universal, energy-based approach to this problem. Instead, dissipative forces play a crucial role. The main goal of the planned project is to clarify the microscopic and mesoscopic origin of the frictional forces and of the energy dissipation in an adhesive contact. Based on this, a concept for the modeling and simulation of adhesive tangential contacts should be developed, implemented in a numerical program and validated experimentally. We are guided by the idea that adhesion on the microscale is dissipation-free and that only instabilities - caused by microscopic heterogeneity of surface chemistry or topography - lead to energy dissipation (and corresponding frictional forces). While this idea is not new in friction physics (Prandtl-Tomlinson model), it has not yet been explicitly applied to tangential adhesive contacts. To achieve this goal, theoretical investigations of heterogeneous contacts are to be undertaken, based on the methods already developed to simulate reversible adhesion. This will go hand-in-hand with systematic experimental investigation of the adhesive tangential contact. A well-founded physical understanding of the dissipative processes in adhesive contacts will lead the way to control of adhesive interactions in practical applications. In particular, the influence of the shape, the roughness, the material heterogeneity and other system parameters that have yet to be determined will be examined theoretically and experimentally.