7. Rolling Friction
What you'll learn
- The mechanics of frictionless rolling
- The dynamics of tractive rolling and tractive friction
- The dynamics of rolling friction
- Why rolling friction is so much lower than sliding friction
- The effects of surface texture and lubrication on rolling friction
- No prerequisites. However, we recommend viewing Module 4 (Dry Friction) and Module 5 (Lubricated Friction) of the Surface Texture and Tribology Short Course prior to viewing this module.
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.
Who this course is for:
- Scientists, engineers, technicians and students in the fields of automotive, medical device, aerospace, materials, polymers, and others
In 1994, Dr. Cohen established Michigan Metrology to help engineers and scientists solve problems related to “Squeaks, leaks, friction, wear, appearance, adhesion and other issues,” using 3D Surface MicroTexture Measurement and Analysis.
Dr. Cohen is a past Chairman of the STLE-Detroit section and has been active with the ASME B46.1 committee on surface texture since 1988, having served as Chair from 2005-2011. Dr. Cohen is also a Subject Matter Expert for the ISO surface metrology activities.
Dr. Cohen has an undergraduate degree in Physics from the University of Michigan, Dearborn, and graduate degrees in Physics and Optical Sciences from the University of Arizona. Early in his career, Dr. Cohen worked with IBM on optical disk drive development. He later joined WYKO Corporation as Product Manger and later became Vice President, leading the development of 3D surface texture metrology instrumentation.
Dr. Cohen has developed this class over the past 20 years having presented the material at numerous client locations as part of his training and consulting activities. Typically once a year the class is offered to a general audience in the Livonia, MI area.