Numerical Simulation of Blast-Induced Mild Traumatic Brain Injury

Blast injury is the leading cause of traumatic brain injury (TBI) in military personnel serving in Iraq and Afghanistan. TBI, caused by blast exposure, has considerable economic, military and social implications. Blast injuries are frequently caused by the high amplitude blasts generated by improvised explosive devises (IEDs). However, even regular training with large caliber weapons appears to cause mild traumatic brain injury (mTBI). The occupational standards of the Armed Forces provide guidelines regarding the maximal peak pressures of blasts and the number of exposures allowed per day, week, etc. These standards are based on acute injuries in ears and/or lungs and not on short- or long term effects on the brain. This paper investigates numerically the propagation of blast waves from the AG90 rifle and through the skull bone and into the brain, in order to understand better of how blast waves can cause brain injury. The numerical simulations were performed with the hydrocode AUTODYN. An idealized head was used in the gunner's position during firing of the relevant weapon. The paper focuses on qualitative mechanisms of blast wave transmission into the brain and investigates in particular the effect of geometry and material parameters.