Probing nonlinear rheology with inertio-elastic oscillations

any common materials display significant nonlinear rheological properties. Characterizing these roperties can be done with a variety of methods. One such method uses inertio-elastic oscillations, hich occur naturally in rotational rheometry as a consequence of a material’s elasticity and the nertia of the rheometer. These oscillations have primarily been used to characterize linear iscoelastic properties. In addition to allowing for the imposition of stress-biased oscillations on hort time scales, we demonstrate that extending this technique to nonlinear deformations provides ccurate measurements of nonlinear material properties. Our experiments are performed on fibrin etworks, which are well characterized and have dramatic nonlinear properties that are biologically ignificant. We compare the tangent moduli measurements of inertio-elastic oscillations with three tandard methods of nonlinear rheology: forced oscillations about a prestress, a geometric nterpretation of large amplitude oscillatory shears, and an extension of the linear viscoelastic oduli to the nonlinear regime. Inertio-elastic oscillations provide an accurate characterization of brin’s nonlinear properties, and further, our measurements suggest that inertio-elastic oscillations rovide the most straightforward method of distinguishing between nonlinear elasticity and issipation at any given stress. In fact, we find that inertio-elastic oscillations provide the most ccurate measurement of the subdominant loss component of our networks. © 2008 The Society of heology. DOI: 10.1122/1.2933171