Deformation, rolling and sliding of particles and particle aggregates

点击翻译按钮获取中文摘要

Particulate systems under external forces, like mechanical load, exhibit reorganization processes on various length and times scales. This project aims at relating macroscopic processes to the motion of single particles. A combination of confocal microscopy and high resolution mechanical testing (like nano indentation and scanning force microscopy) opens the possibility to study the three-dimensional motion of fine particles (diameter larger than 1 µm) under know applied forces with a high spatial and temporal resolution in real systems. We have developed measurement and image analysis techniques to a level that allows an automatic tracking of the translation and rotation of the particles under mechanical load (e.g. shear). With measurements on large particulate systems we aim at identifying and understanding the relevant processes. Thereby we intend to cover a broad range of shear rate, particle shapes, and particle interactions. The results shall be compared to contact mechanics simulations and experiments on real (macroscopic) systems. In parallel we plan to measure the capillary forces between smooth and rough particles. In particular we aim at understanding the dependency of the capillary force on the size and shape of the capillary bridge. In this case also the thickness and viscosity of the liquid film, as well as the velocity of the particle motion shall be varied. We plan to compare the results with energy based Surface-Evolver and molecular dynamics simulations.