An Experimental Investigation of Elastic Plastic Contact and Friction of a Sphere on Flat

An experimental investigation is presented to evaluate recently published models for the contact and sliding inception of a deformable sphere loaded against a smooth rigid flat. The effects of the normal load on the contact area, junction growth, and the static friction force in the elastic-plastic contact regime are presented. Very good correlation is found between the predicted and measured contact area. A dramatic decrease of the static friction coefficient with increasing normal loading is observed, similar to the trend predicted by the model. The quantitative agreement is, however, less satisfying. Some possible reasons for the poor agreement are pointed out.