EXPERIMENTAL IDENTIFICATION OF ELASTIC, DAMPING AND ADHESION FORCES IN COLLISION OF SPHERICAL SLIDERS WITH STATIONARY MAGNETIC DISKS

摘要

This paper deals with the experimental identification of elastic, damping and adhesion forces in the dynamic collision of a spherical slider with a stationary magnetic disk. We used rough Al_2O_3TiC and smooth glass spherical sliders with a radius of 1mm, and magnetic disks with four different lubricant film thicknesses of 0, 1, 2, and 3 nm. We found that the Al_2O_3TiC slider shows ordinary approach and rebound processes, whereas the glass slider showed a velocity drop at the end of the rebound process when the lubricant thickness was 1, 2 and 3 nm. We identified the elastic force factors in the approaching and rebound processes, based on the Herztian contact theory, and the damping force factors based on a damping force model that is proportional to slider velocity and penetration depth (contact area). From the drop in velocity when the slider and disk separated, we found that the dynamic adhesion force is almost equal to the static pull-off force, except for with a 3nm lubricant thickness. The dynamic adhesion force with 3 nm lubricant thickness is significantly higher probably because of squeeze damping effect.