Regensburg 2010 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 75: Nanotribology II

O 75.3: Vortrag

Donnerstag, 25. März 2010, 15:30–15:45, H36

Friction Induced Deformation of Microstructured Rubber Surfaces — •Katrin Brörmann and Roland Bennewitz — INM - Leibniz-Institut für Neue Materialien, Saarbrücken

In an attempt to bridge the gap between macroscopic and microscopic friction measurements, R. Bennewitz et al. [1] introduced a method to analyse friction by means of optical diffraction. In the experiment, a microstructured sample is dragged over a glass surface, resulting in a deformation of the sample due to friction. While sliding, a diffraction pattern of the surface structure is recorded and the strain across the contact, i.e. the average distance between the asperities, is extracted. Simultaneously, the force in normal and lateral direction is measured. PDMS samples with different periodically structured surfaces were used, representing a simple model of multi-asperity contacts.

In a second experiment, the deformation of the sample was observed in real space using an optical microscope. The movement and deformation of the surface structure was tracked and the local trajectories of specific sites on the patterned surface were recorded.

Results of both experiments indicate three phases in the deformation process: first shearing, then the transition from static to kinetic friction and last stick-slip motion. Furthermore, a 2D Poisson’s ratio of the structure can be determined. Details on the phases will be presented and briefly compared to a recent theoretical model.

[1] R. Bennewitz et al., J. Phys.: Condens. Matter 20 (2008) 015004