Friction is a complex subject that we have broken up into multiple modules in this course. Understanding friction is critical in wide-ranging applications, from automotive and aerospace, to rock climbing and curling. In many cases we try to minimize friction (to improve engine performance, for example), but in other cases a high degree of friction is essential (in brake systems, for example). The concepts have been studied since antiquity, and we continue to invest effort and resources into understand and control friction today.

In this module we start by looking at the mechanisms of dry, rolling friction. We then look at tractive rolling and tractive friction, which are critical to getting a vehicle moving and stopping it without sliding. We then move on to rolling friction, which occurs once a wheel or bearing is finally in motion.

The relationship between surface texture (surface roughness), lubrication, and rolling friction is still being studied today, and we go into detail about how texture is (and isn't) responsible for rolling friction. We show why "smooth" is generally better in instances of dry rolling, but how the relationship between texture and rolling friction can be far more complex in lubricated applications.

We encourage you to also view the modules on Dry Friction and Lubricated Friction for a more complete view of the subject matter.

This is Module 7 of the Surface Texture and Tribology Short Course. The full course is available on udemy, or you can select the individual course modules of interest to you. Enter "surface roughness texture tribology" in the udemy search bar to browse the full course and modules.