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

摘要

Traction measurements, like any other physical testing, contain variabilityrnassociated with the test rig, test samples and data acquisition systems. These naturalrnsources of variation were increased when simulating contacts with spin velocity includedrnto the most common rolling and sliding test conditions. Averaging the results within onerntest sequence with spinning, rolling and sliding velocities did not always reflect thernexpected results from the entire population of possible measured values. To be confidentrnin the conclusions that were drawn from the traction testing, it was important to repeat therntest sequence several times and apply statistics for defining error bands around thernexpected traction values. To allow for easy application of error bands, simplifiedrnequations have been curve fit to the data from the numerical routines. By making use ofrnerror bands, an easy determination of the test repeatability can be discerned, andrnquantified comparisons between data sets can be made with a higher degree ofrnconfidence.