Monday  |  Salon 8  |  10:20 AM–10:40 AM

#15802, High-Rate Material Characterization of Porcine Brain Tissue and Formulation of a Scaling Rule Between Fixed and Fresh Tissue Properties

Reliable predictions of biological soft tissue response to mechanical insults require an appropriate resolution of the tissue’s constitutive behavior at a given loading rate. While the determination of low, quasi-static strain rate properties is relatively straightforward and well-established, high-rate material characterization for blast, ballistic, and blunt exposure are difficult to acquire and therefore are still not well-defined in the literature. Computational head models, for example, are used to study traumatic brain injuries and can possess high geometric (anatomic) fidelity. However, uncertainties regarding the high-strain-rate constitutive response of brain tissue remain a significant limitation on the predictive capabilities of such models. As a result, to improve prediction accuracy for models of blast, high-velocity impact, and directed energy loadings, quantitative material characterization of brain tissue at strain rates greater than 10^3 1/s is required. To address and overcome these challenges, we developed a high to ultra-high-rate soft material rheology technique based on inertial microcavitation, termed Inertial Microcavitation Rheology (IMR), which is capable of constitutively characterizing soft tissues and gels at strain rates ranging between ~ 10^3 1/s and 10^8 1/s. Here, we utilize IMR to determine the local material properties for six anatomical regions of the porcine brain that are comprised of white or gray matter. Additionally, by considering both fresh and fixed porcine brain tissue, we aim to develop a biomechanically inspired scaling relationship between the fresh and fixed tissue properties to significantly increase the tissue characterization throughput.

References

[1] Jonathan B. Estrada, Carlos Barajas, David L. Henann, Eric Johnsen, Christian Franck, High strain-rate soft material characterization via inertial cavitation, Journal of the Mechanics and Physics of Solids, Volume 112, 2018, Pages 291-317, https://doi.org/10.1016/j.jmps.2017.12.006.

Elizabeth Bremer   University of Wisconsin-Madison
Anastasia Tzoumaka   Brown University
David Henann   Brown University
Christian Franck   University of Wisconsin-Madison