Cavitation-induced damage model of soft materials in exposure to high-intensity focused ultrasound

Abstract

High-intensity focused ultrasound can drive cavitation bubbles that damage soft materials. A cavitation-induced damage model is developed to study the mechanical damage of soft materials by high-intensity focused ultrasound. Based on the thermodynamics framework with the acoustic radiation stress theory and the nonlinear elasticity theory, an internal variable which reflects the mechanical damage caused by cavitation bubbles is incorporated into the Helmholtz free energy. Thus, the evolution of material damages for tissue-mimicking gel is established, which is related to the cavitation process and the mechanical dissipation from a macroscopic viewpoint. The theoretical model is then applied to analyze the material damaged area observed in the experiment and the theoretical prediction is found in agreement with the existing experimental results, which shows that the damage induced by cavitation bubbles develops rapidly, then slow down and finally reaches a plateau.