Self-regulating performance and flow-field activation mechanism of a sepiolite enhanced shear thickening fluid damper

Shear thickening fluid (STF) has emerged as a promising material for adaptive vibration control, yet remains constrained by insufficient thickening intensity and thermal instability. To address these issues, we developed a sepiolite-enhanced STF (Sep-STF) by incorporating fibrous nanoparticles. Through multi-scale characterization, this study elucidates the critical links between microstructure, rheology, and macroscopic damping performance. Rheological measurements reveal that 3 wt. % Sep-STF maintains stable peak viscosity from 20 to 80 °C, overcoming the thermal degradation observed in pristine STF. Microscopic analyses confirm that sepiolite nanofibers form hydrogen-bonded networks with SiO2 particles, reinforcing shear-induced clustering and suppressing high-temperature rheological decay. Under dynamic loading, the Sep-STF damper achieves its highest adjustable stiffness (Kδ = 18.54) and maximum equivalent damping coefficient (Ceff = 669.06 N s/m) at 20 °C and 10 mm amplitude. Additionally, integrated COMSOL Multiphysics simulations and analytical models based on a parallel-plate flow theory quantitatively correlate damping force with fluid rheology, channel gap, and piston velocity. This work provides a robust theoretical–experimental foundation for developing next-generation passive intelligent dampers with real-time, parameter-driven performance capabilities.