Soft material mechanical property determination using a modified Rayleigh collapse time*

The high-fidelity determination of soft material mechanical properties in the high strain rate regime has the potential to improve the efficacy of biomedical procedures involving microcavitation. Inertial Microcavitation Rheometry (IMR) is a technique comparing bubble radius histories from numerical simulations and laser-induced cavitation (LIC) experiments to identify the material constitutive model and associated parameters [Estrada et al. JMPS 2017]. We consider an initially spherical bubble at its maximum radius out of equilibrium. We present a method to expedite the model fitting process via an analytical collapse time constraint. The collapse time is derived by accounting for the energy transfer throughout the collapse. We show that the augmented collapse time accounts for surface tension, weak compressibility, and linear viscoelastic constitutive models. We obtain agreement between theory, numerical simulations, and LIC experimental data for various PEG-DA and polyacrylamide gels.