Dear All, I am looking for a method to calculate the friction stresses created in 1 mm thick, fully supported, slide of soda-lime silica glass. In this experiment a 1/4" ball bearing of various metals is being translated over the glass surface under a constant load of 2000g. The glass slide is then being tested to evaluate the breaking force in order to ascertain if the metal damaged the glass surface. In a further experiment I have evaluated the static coefficient of friction between the 1/4" ball bearing and the glass. What I am interested in is to evaluate the friction stresses as these are related to the creation of damage on the glass surface.