Figure 1. Diagram of ratchet-like frictional anisotropic systems.

First column, stiff protuberances on a stiff supporting layer. Second column, soft protuberances on a stiff supporting layer. Third column, stiff protuberances on a soft supporting layer. The third (framed) column indicates the system considered in the present study. First row, systems in non-deformed state. Second row, deformation caused by sliding in the direction of the protuberance slope. Third row, deformation caused by sliding in the direction opposite to the protuberance slope.