Stability and simulations of insonated contrast agents-effect of the constitutive law

Abstract

Under insonation contrast agents are known to exhibit dynamic patterns such as thresholding, compression only behavior, diffusion and deflation, shape deformation, buckling, jetting and break-up, not all of which can be adequately predicted based on a single model describing the mechanics of the coating. Strain softening and strain hardening behavior in the presence of a folding instability are investigated as a means to understand compression only behavior in conjunction with the high harmonic content often recorded in optical and acoustic measurements of pulsating contrast agents coated by a phospholipid monolayer. Numerical simulations are presented that capture shape mode excitation and buckling of the coating and an association is made with the above phenomena.