In-situ characterization of three dimensional worn surface under sliding-rolling contact

Rolling bearing performance often degrades due to extra wear introduced by sliding-rolling contacts. Thus, it is vital to monitor the evolution of such wear process through investigating the worn surface. Compared with traditional two-dimensional (2-D) methods, three-dimensional (3-D) measurements of worn surfaces can provide more information. Due to the lack of in-situ 3-D measurement techniques and the scale-dependency of characterization parameters, it remains a challenge to examine the wear evolution of sliding-rolling contact using 3-D surface topography features. A characterization framework is here developed for inspecting worn surface topography variations under sliding-rolling contact, by combing 3-D surface reconstruction and computed fractal dimension. The worn surface is firstly imaged by an in-situ microscope. Next, a virtual 3-D surface is obtained from 2-D images via topography reconstruction. Then, the fractal dimension of worn surfaces is calculated to characterize the wear state with 3-D root-mean-square. A wear test is carried out on a roller-ring test rig to verify the proposed method. Results indicate that the proposed 3-D characterization performance is comparable to laser scanning confocal microscopy (LSCM) and allows rapid description of the wear process.