LABORATORY TESTING OF DISPLACEMENT AND LOAD-INDUCED FRETTING

A conceptually new simulation system for the laboratory investigation of fretting wear is described. Fretting vibrations are generated either directly by oscillating a linear relative displacement device of constant stroke between the contacting bodies or indirectly by oscillating the applied contact load resulting in a cyclic radial expansion of the contact zone. The principles of both actuation mechanisms are outlined in detail, indicating the precision and performance range of the simulation system. A data acquisition and evaluation strategy has been developed for the online characterization of the mechanical contact response. It is based on the measurement of the contact displacement, tangential force and normal load. Typical experimental results obtained under different testing conditions are presented for hard coatings such as TiN and diamond deposited on flat samples and vibrating against corundum counterbody balls.