A new pressure sensor array for local normal stress measurement in complex fluids, Journal of Rheology 65, 583 (2021)

– A new pressure sensor array for local normal stress measurement in complex fluids, Journal of Rheology 65, 583 (2021) ;
Gauthier Anaïs, Pruvost Mickaël, Gamache Olivier, Colin Annie,

https://doi.org/10.1122/8.0000249

Résumé :
A new pressure sensor array, positioned on the bottom plate of a standard torsional rheometer is presented. It is built from a unique piezo-capacitive polymeric foam, and consists of twenty-five capacitive pressure sensors (of surface 4.5×4.5 mm2 each) built together in a 5×5 regular array. The sensor array is used to obtain a local mapping of the normal stresses in complex fluids, which dramatically extends the capability of the rheometer. We demonstrate this with three examples. First, the pressure profile is reconstructed in a polymer solution, which enable the simultaneous measurement of the first and the second normal stress differences N1 and N2, with a precision of 2 Pa. In a second part, we show that negative normal stresses can also be detected. Finally, we focus on the normal stress fluctuations that extend both spatially and temporally ina shear-thickening suspension of cornstarch particles. We evidence the presence of local a unique heterogeneity rotating very regularly. In addition to their low-cost and high versatility, the sensors show here their potential to finely characterize the normal stresses in viscosimetric flows.

A new pressure sensor array for local normal stress measurement in complex fluids, preprint, 2020, https://arxiv.org/abs/2010.04474