In order to expand on potential injury mechanisms to the brain, a micromechanical structural representation of the gray matter must be developed. The gray matter contains a high volume of capillary vasculature that supplies the necessary oxygen required for maintaining healthy cell and brain function. Even short disruptions in this blood supply and the accompanying dissolved oxygen can lead to neuronal cell damage and death. It has been shown that increased shearing forces within the blood, such as those found near stents and artificial heart valves, can lead to platelet activation and aggregation, causing clots to form and potential disruptions in blood flow and oxygen distribution. Current macro-scale computational brain modeling can incorporate the larger main vasculature of the brain, but it becomes too computationally expensive to incorporate the smaller vessels. These larger scale models can be used to reveal how forces to the head are transmitted down to a scale slightly larger than the smallest capillaries within the gray matter. In order to investigate the response and potential damage to capillaries and platelets within the brain, a micromechanical computational model is developed incorporating the gray matter, capillaries, and blood, which is composed of plasma, red blood cells, and platelets. The red blood cells are a necessary component for the model for damage as it comprises almost half of the volume of blood and is the major contributor to the non-Newtonian behavior. The model combines both fluids and viscoelastic solid materials (the gray matter and the vascular wall). The deviatoric stress, strain and strain rate of the platelets in response to an externally applied load is measured and will determine the potential for platelet aggregation and clot formation. The micromechanical model is also used to provide verification and refinement for existing constitutive models for the gray matter used in meso- and macro-scale computational models.

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