Probing viscoelasticity of dilatant fluid by solid projectile impact

Dilatant fluids offer complex rheological properties such as discontinuous shear thickening (DST). In recent years, various solid-impact experiments onto a dilatant fluid have been performed to reveal the physical properties of DST. Interesting phenomena such as dynamic jamming [S. R. Waitukaitis & H. M. Jaeger,Nature 487, 205(2012)] and dynamic fracturing[M. Roche et al., Phys. Rev. Lett. 110 148304(2013)] have been reported in previous reserches. In addition, peculiar surface deformation of the vibrated dilatant fluid has also been found[F. S. Merkt et al., Phys. Rev. Lett. 92 184501(2004)]. In this study, we perform a simple solid-projectile impact to a dilatant-fluid target to observe the penetration and rebound dynamics. In addition, to investigate the effect of vibration to the rheological properties of dilatant fluid, mechanical vibration is also applied to the dilatant fluid. From these results, the rebound timescale and restitution coefficient are measured. To characterize the viscoelasticity, we assume a simple attenuating-oscillation model. Using the model, the effects of impact inertia, boundary conditions, and mechanical vibration to the rheological properties are systematically studied.