High strain-rate material characterization of biological tissue using inertial microcavitation rheometry
Abstract
Traumatic brain injuries can be caused by blast or blunt-impact loads to the head and are a pervasive and debilitating injury amongst warfighters. Progress has been made in understanding the mechanisms of traumatic brain injury using finite-element-based head models, but the high-strain-rate constitutive behavior of brain tissue, which is required as an input to computational head models, remains a source of uncertainty in model predictions. Therefore, there is a need for improved mechanical characterization of biological tissues, such as brain tissue, in order to achieve improved predictions of the effects of traumatic brain injuries. Calibrated, predictive constitutive models for soft biological tissue materials are currently lacking because applying traditional high-strain-rate material characterization techniques (e.g., Kolsky bar or Taylor plate-impact testing) to soft materials is tremendously challenging. To address this need, a new soft-material characterization technique has been developed usingmeasurements of the dynamics of isolated bubbles generated by laser or acoustic pulses. Using high-speed imaging of the bubble dynamics along with a theoretical cavitation modeling framework provides a route to high-strain-rate soft material characterization, and this approach has been shown to be able to discern mechanical properties at previously undocumented strain-rates in materials as soft as a few kPa, such as polyacrylamide gels. In the proposed project, this promising approach will be leveraged and applied to obtaining calibrated high-strain-rate constitutivemodels for brain tissue. Data fromlaser-induced cavitation experiments in tissue fromseveral different anatomical regions of pig brains (whitematter, graymatter,midbrain, hippocampus, etc.) will be generated by collaborators and shared with the PI prior to the beginning of the proposed work. Numerical simulations of the cavitation process will be performed, and model predictions will be fit to the experimental data in order to determine the high-strain-rate constitutive behavior of the different regions of pig brain tissue. Successful completion of the proposed work would provide the first application of the cavitation-based characterization approach to biological tissue and the first set of robust, large-strain, high-strain-rate material properties for brain tissue. This information may then be used in the subsequent study of traumatic brain injury using computational head models, which will enable improved strategies for mitigating and preventing traumatic brain injuries both in the armed forces and amongst civilians (e.g., in sports-related injuries).
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 15, 2021
- Source ID
- N000142112109
Entities
People
- David L. Henann
Organizations
- Brown University
- Office of Naval Research
- United States Navy