Low-speed impact characteristics of shear thickening fluids: theoretical prediction model and experimental verification

Abstract

Shear thickening fluids (STFs) are a type of non-Newtonian fluid that disperses particles at the micrometer or nanometer scale into a liquid medium, forming a particle suspension. The viscosity of STF increases with increasing shear rate when the shear rate is above a critical value. During external load impact, STF can absorb substantial impact energy, effectively mitigating shocks and vibrations. This paper focuses on the dynamic characteristics of STFs with different dispersion systems, including cornstarch-water STFs and silica-polyethylene glycol (SiO₂-PEG) STFs under low-speed impact. First, from an energy perspective, this paper established a theoretical model to study the impact properties of STFs considering the viscosity characteristic of STFs. Further, the model is numerically solved using the Runge–Kutta method, and variation of impact displacement, velocity, acceleration, and impact force with time during the impact process can be obtained. Then, the rheological properties of STFs were studied, and viscosity models of different STFs were fitted through experimental results. Finally, impact experiments were carried out with a falling hammer onto STFs to validate the established theoretical model. A good consistency between theoretical model and experiments was achieved. Results in this paper show different impact response mechanisms between cornstarch-water STF and silica-polyethylene glycol STF. The former experiences thickening at the moment of impact, resulting in a quasi-solid state phenomenon that generates a significant reverse impact force to slow down the falling hammer. In the latter, the thickening effect creates viscous resistance on the falling hammer, and a smaller impact force is produced.

Graphical Abstract