The rolling resistance is a force resisting the motion when a body is rolling across a surface. This determines the slip resistance of, e.g., car or truck tires.
Formula and Dependence
The rolling resistance only depends on the coefficient of rolling friction, cR. The rolling resistance depends on material and surface size (R = radius) used for the rubber “wheel”.
FR = cR · FN
cR, the rolling coefficient
FN, the normal Force
d, the distance that FN is altered if the object is moving
How to measure the rolling resistance?
The measurement of the rolling resistance of a tire is performed in a drum tester. A cylinder made of concrete (or any metal) is electrically driven with a constant speed. The test wheel is in contact with the rotating drum and rotates with the speed of the drum. Due to varying rolling resistance properties, different tires will be distinguish during this test by their measured energy consumption.
Dynamic-mechanical analysis (DMA) is a test method which measures the entire energetic loss. This yields results comparable to those of testing entire tires with drum testers.
For these tests, the DMA GABO Eplexor®® can be used.