Statistical Analysis of Traction Measurements with Rolling, Sliding, and Spin

摘要

Traction measurements, like any other physical testing, contain variability associated with the test rig, test samples, and data acquisition systems. These natural sources of variation increased when simulating contacts with spin velocity in the most common rolling and sliding test conditions. Averaging the results within one test sequence with spinning, rolling, and sliding velocities did not always reflect the expected results from the entire population of possible measured values. To be confident in the conclusions that were drawn from the traction testing, it was important to repeat the test sequence several times and apply statistics for defining error bands around the expected traction values. To allow for easy application of error bands, simplified equations were curve fit to the data from the numerical routines. By making use of error bands, an easy determination of the test repeatability can be discerned, and quantified comparisons between data sets can be made with a higher degree of confidence.