Indentation versus Rolling: Dependence of Adhesion on Contact Geometry for Biomimetic Structures.
Indentation versus Rolling: Dependence of Adhesion on Contact Geometry for Biomimetic Structures.
复制标题
压痕与滚动：仿生结构的粘附力对接触几何形状的依赖性。
作者：
N. Moyle;Zhenping He;Haibin Wu;C. Hui;A. Jagota
已经开发了许多由弹性体材料制成的仿生结构，以产生诸如粘附、静摩擦和滑动摩擦的性能的增强。作为一种性质，人们期望用单位面积的能量来表示粘附力，该能量通常对裂纹前缘处的剪切应力和法向应力的组合敏感，但在其他方面仅取决于在界面处相遇的两种弹性材料。更具体地说，人们会期望通过压痕（一种流行且方便的技术）测量的粘附力可以用于预测更实际重要的滚动几何形状中的粘附滞后。以前，具有膜终止的纤维状几何形状的结构在与刚性球体的压痕期间通过裂纹捕获机制表现出粘附力的显著增强。大致各向同性的结构，如纤维状的几何形状显示出很强的相关性之间的粘合增强压痕与粘合滞后滚动。然而，各向异性结构，例如膜终止的脊通道几何形状，令人惊讶地显示出通过压痕与滚动测量的粘附力之间的显着差异。我们研究这个实验和理论上，首先比较的各向异性的脊通道结构的粘附力的大致各向同性的纤维状结构在压痕与刚性球，其中只有各向同性的结构显示出粘附力增强。其次，我们研究更详细的异常各向异性膜终止的脊通道结构在压痕与刚性球与滚动，以显示为什么这些结构显示出显着的粘附力增强滚动的情况下，没有粘附力增强压痕。
Numerous biomimetic structures made from elastomeric materials have been developed to produce enhancement in properties such as adhesion, static friction, and sliding friction. As a property, one expects adhesion to be represented by an energy per unit area that is usually sensitive to the combination of shear and normal stresses at the crack front but is otherwise dependent only on the two elastic materials that meet at the interface. More specifically, one would expect that adhesion measured by indentation (a popular and convenient technique) could be used to predict adhesion hysteresis in the more practically important rolling geometry. Previously, a structure with a film-terminated fibrillar geometry exhibited dramatic enhancement of adhesion by a crack-trapping mechanism during indentation with a rigid sphere. Roughly isotropic structures such as the fibrillar geometry show a strong correlation between adhesion enhancement in indentation versus adhesion hysteresis in rolling. However, anisotropic structures, such as a film-terminated ridge-channel geometry, surprisingly show a dramatic divergence between adhesion measured by indentation versus rolling. We study this experimentally and theoretically, first comparing the adhesion of the anisotropic ridge-channel structure to the roughly isotropic fibrillar structure during indentation with a rigid sphere, where only the isotropic structure shows adhesion enhancement. Second, we examine in more detail the anomalous anisotropic film-terminated ridge-channel structure during indentation with a rigid sphere versus rolling to show why these structures show a dramatic adhesion enhancement for the rolling case and no adhesion enhancement for indentation.