This paper is devoted to an analytical, numerical, and experimental analysis of adhesive contacts subjected to tangential motion. In particular, it addresses the phenomenon of instable, jerky movement of the boundary of the adhesive contact zone and its dependence on the surface roughness. We argue that the “adhesion instabilities” with instable movements of the contact boundary cause energy dissipation similarly to the elastic instabilities mechanism. This leads to different effective works of adhesion when the contact area expands and contracts. This effect is interpreted in terms of “friction” to the movement of the contact boundary. We consider two main contributions to friction: (a) boundary line contribution and (b) area contribution. In normal and rolling contacts, the only contribution is due to the boundary friction, while in sliding both contributions may be present. The boundary contribution prevails in very small, smooth, and hard contacts (as e.g., diamond-like-carbon (DLC) coatings), while the area contribution is prevailing in large soft contacts. Simulations suggest that the friction due to adhesion instabilities is governed by “Johnson parameter”. Experiments suggest that for soft bodies like rubber, the stresses in the contact area can be characterized by a constant critical value. Experiments were carried out using a setup allowing for observing the contact area with a camera placed under a soft transparent rubber layer. Soft contacts show a great variety of instabilities when sliding with low velocity — depending on the indentation depth and the shape of the contacting bodies. These instabilities can be classified as “microscopic” caused by the roughness or chemical inhomogeneity of the surfaces and “macroscopic” which appear also in smooth contacts. The latter may be related to interface waves which are observed in large contacts or at small indentation depths. Numerical simulations were performed using the Boundary Element Method (BEM).

本文致力于对受到切向运动的粘附接触进行解析、数值和实验分析。特别是，它解决了粘合剂接触区边界不稳定、突然运动的现象及其对表面粗糙度的依赖性。我们认为，与弹性不稳定性机制类似，接触边界不稳定运动的“粘附不稳定性”会导致能量耗散。当接触面积膨胀和收缩时，这会导致不同的有效粘附工作。这种效应被解释为接触边界运动的“摩擦”。我们考虑摩擦的两个主要贡献：（a）边界线贡献和（b）面积贡献。在法向和滚动接触中，唯一的贡献是由于边界摩擦，而在滑动时，两种贡献都可能存在。边界贡献在非常小的、光滑和硬接触（例如类金刚石碳 (DLC) 涂层）中占主导地位，而面积贡献在大的软接触中占主导地位。模拟表明，由于粘附不稳定性引起的摩擦受“约翰逊参数”控制。实验表明，对于像橡胶这样的软体，接触区域的应力可以用一个恒定的临界值来表征。使用允许使用放置在柔软透明橡胶层下的相机观察接触区域的设置进行实验。软接触在低速滑动时表现出各种各样的不稳定性——这取决于压痕深度和接触体的形状。这些不稳定性可以归类为由表面的粗糙度或化学不均匀性引起的“微观”和也出现在光滑接触中的“宏观”。后者可能与在大接触或小压痕深度处观察到的界面波有关。使用边界元法 (BEM) 进行数值模拟。