A systematic characterization of the motion and friction of a linear bearing with rolling elements used for nanopositioning reveals an explicit distinction of static and rolling friction. The effects

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Most friction models for automatic control are targeted for the macro world, and are of questionable value for the motion control of the high precision positioing stages. We published a paper recently in Technishes Messen (TM) on a study of the friction behavior in the moving range of micrometers. It provides info for the development of friction models targeted for the motion control in high precision engineering.

The following is the abstract, and the full paper can be downloaded from http://www.atypon-link.com/OLD/doi/abs/10.1524/teme.2006.73.9.500

ABSTRACT Most friction models for automatic control are targeted for the macro world, and are of questionable value for the motion control of the nanopositioning and nanomeasuring machine (NPM) system. We present the frictional behaviour of some selected materials, coatings, lubricants, and bearings tested under running conditions similar to a NPM system. Continuous change of surface properties results in various friction characteristics, which substantiate the further development of tribological coatings, particularly for vacuum applications. We emphasize the system engineering approach in developing friction models, which combines fundamental knowledge of surface science, materials science, and its applications in design, construction and automatic control.

We published this paper in APL on a study of the deformation near interfaces. It provides insight in the strain localization at the interface and its influence on the deformation in bulk metals. 

Abstract An optical full-field strain mapping technique has been used to provide direct evidence for the existence of a highly localized strain at the interface of stacked Nb/Nb bilayers during the compression tests loaded normal to the interface. No such strain localization is found in the bulk Nb away from the interface. The strain localization at the interfaces is due to a high void fraction resulting from the rough surfaces of Nb in contact, which prevents the extension of deformation bands in bulk Nb crossing the interface, while no distinguished feature from the stress-strain curve is detected.