Cavitation and shock waves in shear-thickening fluids

Shear thickening fluids (STFs) exhibit a dramatic increase in viscosity when exposed to high strain rates, making them ideal candidates for protective equipment and industrial damping systems. Although numerous studies have shown that the addition of STFs to Kevlar fabrics and foams improves shock absorption, there is still little experimental data on shock wave propagation, cavitation nucleation and dynamics, and crack propagation in these fluids. Visualizing such phenomena with conventional imaging techniques is difficult due to the small spatio-temporal scales of the processes and the opacity of many shear-thickening media. We therefore separately investigate the dynamics of single, laser-induced cavitation bubbles in optically transparent STFs with high-speed visible light imaging and the propagation of shock waves in opaque STFs impacted by high-energy shocks with high-speed phase-contrast X-ray imaging. Initial results indicate that the collapse of a single bubble in STFs is less damaging to a neighbouring wall compared to water and that cavitation bubbles nucleate after the passage of a shock wave through STFs.