Institut fuer Werkstoffphysik und Werkstofftechnologie, Technische Universitaet Hamburg-Harburg, Hamburg Institut für Werkstoffforschung, Werkstoffmechanik, Helmholtz-Zentrum Geesthacht, Geesthacht
The phenomenon of surface stress – the presence of forces at solid surfaces that tend to compress or expand the underlying bulk tangentially to the surface plane – is typically discussed with attention to the planar single crystal surface. Yet, more often than not, surfaces in experiment exhibit corrugation or faceting. In some instances step edges accommodate curvature or misorientation relative to a low-index orientation. In others, growth phenomena create islands with inclined boundaries. Furthermore, surface stresses act on internal interfaces in materials. The microstructure will then typically contain curved interfaces which assume various orientations, covering the full 3D orientation space. Thus, the surface topology affects the impact of the surface stress on the materials behaviour and the experimental observations. Mechanics provides local balance equations for stress at a curved segment of surface. Yet, investigating capillary forces acting on real materials surfaces with a complex geometry typically requires statements for averages that depend on suitable statistical variables, linking the geometry to the mechanics. The talk advertises examples where these problems are relevant and where solutions from surface mechanics can be compared to experiment.