Computer modeling methodology in the simulation of brain injuries due to blasts and impact

Namas Chandra, Ph D, PE
Center for Injury Biomechanics, materials and medicine (CIBM3), NJIT


Abstract

Warfighters and peacekeepers face continued blast threats from IEDs and landmines. Motor vehicle accidents, sports concussions and fall all cause head and brain injuries. Computer modeling has played a vital role in understanding the injury event and the prediction of the injury severity. The acute and chronic neurological, pathophysiological, and behavioral effects of single or repeated exposures to blasts are not known. We have combined an integrated approach of experiments and computations to answer these questions. Based on MRI/CT data on human beings and animal models, anatomically accurate geometric models as well as 3D finite element models have been built. The numerical model is then validated based on experimental data available in literature. Also, different size shock tubes were carefully designed and built; the blast characteristics inside the tube are then validated against measurements in actual field blast testing. The blast tubes will be operational in early spring 2014 and will be housed in the basement of GITC building. These validated primary blasts are then used to test on head forms, Post-Mortem Human Surrogates (cadavers), and a series of animal models (rodents and pigs). Precise stress measurements in PMHS and animal models show sharp pressure pulses in the front and diffuse pulses throughout the brain. Histological and immune-histo-chemical and proteomic measurements show blood-brain barrier damage and neuronal plasma permeability in different regions of brain. Based on mortality, a dose-response curve has been developed that relates peak overpressure (and hence different explosive strengths) to injury. Some in-vitro results of neuron stretch injury model under different strain and strain-rates are also presented.