Calendar

Abstract

Inertial cavitation is a common phenomenon found in nature and many engineering systems. When harnessed carefully, focused, energy-driven cavitation can be a very beneficial tool in a wide range of medical and materials applications including laser surgery, lithotripsy, drug delivery, and more recently, soft material characterization. In this talk, we will describe three recent developments in material property characterization, dynamic instability analysis, and quantitative full-field deformation measurements to investigate laser-induced inertial cavitation (LIC) in hydrogels, where the surrounding material is subjected to ballistic and ultra-high strain rates (10^3 ~ 10^8 s^-1).

We begin by extending our previously developed laser-based Inertial Microcavitation Rheometry (IMR) framework to accurately determine the nonlinear viscoelastic, finite deformation constitutive behavior of soft materials at ultra-high strain rates. We will demonstrate our method’s capability by testing various concentrations of agarose hydrogels. We find a noticeable transition in the constitutive properties as the concentration of agarose increases beyond 2.5%, which is reflected by a significant change in the underlying material microstructure that is strongly gel concentration-dependent. At such high rates, for example in agarose LIC experiments, soft hydrogels/biological materials exhibit significant strain stiffening effects, dynamic surface instabilities, and fracture patterns. Next, we will present our developed new theoretical framework to predict the onset and dynamic evolution of these instability phenomena. Lastly, we will introduce a unique combination of our adaptive mesh digital image correlation (DIC) method and laser-induced inertial cavitation experiments, which provide powerful means for quantitatively capturing extremely complex soft material deformations and subsequent material damage at high strain rates. We will illustrate exciting new avenues of this method by examining more complicated, non-spherically symmetric bubble dynamics including the evolution of cavitation damage along a soft material interface, cavitation near a rigid wall, and cavitation in a 3D printed material. All these are of significant interest in many cavitation-related applications including advanced laser & ultrasound surgeries, tissue engineering, and advanced manufacturing.