Laboratoire de Sciences et Ingéniérie de la Matière Molle (SIMM), UMR CNRS 7615, Ecole Supérieure de Physique et Chimie Industrielles (ESPCI), Paris, France.
J R Soc Interface. 2013 Apr 3;10(83):20130182. doi: 10.1098/rsif.2013.0182. Print 2013 Jun 6.
The shear failure and friction mechanisms of bioinspired adhesives consisting of elastomer arrays of microfibres terminated by mushroom-shaped tips are investigated in contact with a rigid lens. In order to reveal the interplay between the vertical and lateral loading directions, experiments are carried out using a custom friction set-up in which normal stiffness can be made either high or low when compared with the stiffness of the contact between the fibrillar adhesive and the lens. Using in situ contact imaging, the shear failure of the adhesive is found to involve two successive mechanisms: (i) cavitation and peeling at the contact interface between the mushroom-shaped fibre tip endings and the lens; and (ii) side re-adhesion of the fibre's stem to the lens. The extent of these mechanisms and their implications regarding static friction forces is found to depend on the crosstalk between the normal and lateral loading directions that can result in contact instabilities associated with fibre buckling. In addition, the effects of the viscoelastic behaviour of the polyurethane material on the rate dependence of the shear response of the adhesive are accounted for.
研究了由微纤维阵列的弹性体组成的仿生物胶粘剂的剪切失效和摩擦机理，这些微纤维的末端是蘑菇形状的尖端，与刚性透镜接触。为了揭示垂直和水平加载方向之间的相互作用，使用定制的摩擦装置进行了实验，该装置可以使正常刚度与纤维状胶粘剂与透镜之间的接触刚度相比变得更高或更低。通过原位接触成像，发现胶粘剂的剪切失效涉及两个连续的机制：（i）蘑菇状纤维尖端末端与透镜之间的接触界面的空化和剥落；（ii）纤维的茎部重新与透镜的侧方重新粘合。这些机制的程度及其对静摩擦力的影响取决于正常和水平加载方向之间的串扰，这可能导致与纤维屈曲相关的接触不稳定性。此外，还考虑了聚氨酯材料的粘弹性行为对胶粘剂剪切响应的速率依赖性的影响。
