Stress, strain, and flow produced by a vibrator in, or on the surface of, a soft solid

The field of biomedical ultrasound is greatly indebted to Edwin Carstensen for important contributions, without number, that he and his associates have made to understanding of the subject. These contributions have dealt not only with linear and nonlinear propagation of ultrasound in biological materials, but also with effects produced by ultrasound through various thermal and nonthermal mechanisms. Such understanding is important for advancing benefits and minimizing risks in applications of ultrasound. Many therapeutic applications discussed in the literature utilize focused beams of megahertz frequency, while others employ lower frequencies. In this talk, some findings will be presented from experiments in which a vibrating source of frequency in the range 20–90 kHz is brought into contact with the surface of a soft viscoelastic solid and information is obtained on resulting fields of strain. Under some conditions the mechanical properties of the solid are altered by an exposure, in an apparent change ...