Topic 7: The Contact Conundrum

Understanding the area of contact between two solids is fundamental to tribology and many books have been written on the subject. At least for smooth elastic surfaces, the ideas of Hertz, that he formulated over a single Christmas holiday in the 19^th Century, have been used ever since as the basis for calculation contact areas. However, the real engineering situation is much more complex, described by Archard as being due to the contact between rough surfaces having “protuberances on protuberances on protuberances”…