Modelling Nanoscale Cellular Structures Using Molecular Dynamics

Murphy, M. A., Horstemeyer, M., & Prabhu, R. (2021). Modelling Nanoscale Cellular Structures Using Molecular Dynamics. Multiscale Biomechanical Modeling of the Brain. Cambridge, Massachusetts: Academic Press. 53-76. DOI:10.1016/B978-0-12-818144-7.00001-3.

The continuum assumptions in many macroscale modeling of the brain require a physics basis in order to be predictive; thus, requiring lower length scale information arising from upscaling methods from lower length scale simulations. These simulations enable properties of interest to be identified, quantified, and incorporated into macroscale constitutive material models. Herein, the molecular dynamics method, a stochastic method based on Newton's equations of motions, is used to explore how fat membranes on the outside of a neuron, which are prolific throughout the brain, deform with a focus on the equibiaxial strain state as a representative case. This example demonstrates how mechanisms the affect the cellular response to traumatic brain injury can be modeled using nanoscale methods. These properties can be upscaled into a macroscale mechano-physiological internal state variable material model and used to infer cellular and tissue death arising from mechanical impacts. Additionally, the concept of a membrane failure limit diagram is presented so that the macroscale failure strains can be defined.