A Device for High-Strain-Rate Cavitation

Cavitation events within and near soft solids can arise from shock loading, phase change, and acoustic waves; all involve high-rate failure at the surface of the deforming solid. In exploring these, the rate of loading and total energy input can be either challenging or impossible to control independently, further complicating analysis of high rate elastic cavitation. Recently, a technique known as cavitation rheology has been used to understand both elastic and failure responses of soft solids through the pressurization of a cavity, at a controlled rate. However, the loading rates allowed by a typical instrument cannot probe the high rates typical of the extreme loads listed above. To address this, we have developed a device that capable of high-strain-rate cavitation. The cavities that form mimic temporary cavities observed in ballistic impact. An experiment is performed by injecting high pressure air, moving at the acoustic limit and controlled via a piezo-actuated valve, into a soft material. Energy input from a single injection is controlled via the combination of the reservoir temperature and pressure and the actuation time. Using a range of pressures (3-30 MPa) and needle diameters (100-130 μm) we can impart energy densities on time scales relevant to ballistic impacts.