Normal rheological behavior and theoretical modeling of sepiolite shear thickening fluid

Recently, the majority of studies on shear thickening fluid (STF) have considered shear rheology and viscosity, while the normal force has been neglected. Notably, investigation of the normal force is essential for elucidating the shear-thickening mechanism and expanding the practical applications of STF. Hence, in this study, a rotating rheometer was used to examine the variation in the normal force on sepiolite shear thickening fluid (Sep-STF) under different loading rates since Sep-STF exhibited a high shear-thickening performance in a prior study. The results show that the normal load-bearing capacity and energy absorption ability of Sep-STF exceeded those of pure STF. Specifically, the energy absorption capacity of Sep-STF increases by an impressive 857.40% compared with pure STF under a loading rate of 60 μm/s. An extrusion flow model derived from a piecewise power-law viscosity function coupled with the Navier boundary slip condition was proposed to analyze the velocity field and shear stress gradient distributions of Sep-STF. The normal force results obtained from this model were consistent with experimental data. Therefore, this study provides a platform allowing researchers to investigate more high-precision vibration-damping devices.