Impacts on Suspensions of Cornstarch in Water

Non-Newtonian fluids can exhibit a variety counterintuitive phenomena.  One example is a suspension of cornstarch in water, which has the ability to absorb incredible amounts of momentum on impact.  The mechanism for this phenomenon has not been understood using traditional shear rheology.  To study impact-activated solidification and momentum absorption within the cornstarch suspensions, we use high-speed videography in conjunction with an ElectroPuls E1000 materials tester which impacts the surface of the suspension while measuring the force and position.  We observe that a transient solid-like front grows out from the point of impact.  We report measurements of the load carried by the suspension and how it changes depending on whether the front reaches the boundaries of the system.