Fig. 2: High-speed stress microscopy.
From: Stress distribution and surface shock wave of drop impact
a A schematic showing the principle of high-speed stress microscopy. A drop falls from a height h and impacts onto the surface of a particle-embedded PDMS gel at an impact velocity U. Lower left inset: An image of the PDMS gel embedded with fluorescent particles under the illumination of the laser sheet. b Comparison of the shear stress (top) and the pressure (bottom) induced by the impact of a steel sphere obtained from high-speed stress microscopy (left) and from finite element simulations (right). The diameter and the impact velocity of the steel sphere are D = 3.16 mm and U = 0.49 m/s, respectively. The stresses are measured at time t = 0.25 ms after the instant when the sphere first touches the solid surface.
