Stress Field at a Sliding Frictional Contact: Experiments and Calculations

Using a MEMS-based sensing device, we have measured the normal and tangential stress fields at the base of a rough elastomer layer in contact with a smooth glass cylinder in steady sliding. This geometry allows for a direct comparison between the stress profiles measured along the sliding direction and the predictions of an original exact bidimensional model of friction. The latter assumes Amontons’ friction law, i.e. that the interfacial tangential and normal stress components are proportional, with a pressure-independent dynamic friction coefficient μd, but makes no further assumption on the normal stress field. Discrepancy between the measured and calculated profiles is found to be less than 10% over the range of loads explored. Comparison with a test model, which postulates that the normal stress field is unchanged upon tangential loading, shows that the exact model better captures the experimental profiles at high loads. However, significant deviations not accounted for by either calculations still remain. In that regard, the relevance of two assumptions made in the calculations, namely (i) the smoothness of the interface and (ii) the pressure-independence of μd is briefly discussed.