STUDY OF BLAST-INDUCED MILD TRAUMATIC BRAIN INJURY: LABORATORY SIMULATION OF BLAST SHOCK WAVES

Abstract

Blast-induced mild traumatic brain injury (BImTBI) is one of the most common causes of traumatic brain injuries. BImTBI mechanisms are not well identified, as most previous blast-related studies were focused on the visible and fatal injuries. BImTBI is a hidden lesion and long-term escalation of related complications is considered a serious health care challenging due to lack of accurate data required for early diagnosis and intervention. The experimental studies presented in this thesis were performed to investigate aspects of blast shock wave mechanisms that might lead to mild traumatic brain injury. A compressed air-driven shock tube was designed and validated using finite element analysis (FEA) and experimental investigation. Two metal diaphragm types (steel and brass) with three thicknesses (0.127, 0.76, and 0.025mm) were utilized in the shock tube calibration experiment, as a new approach to generate shock wave. The consistency of generated shock waves was confirmed using a statistical assessment of the results by evaluating the shock waves parameters. The analysis results showed that the 0.127mm steel diaphragm induces a reliable shock waveform in the range of BImTB investigations. Evaluation of the shock wave impacts on the brain was examined using two sets of experiments. The first set was conducted using a gel brain model while the second set was performed using a physical head occupied with a gel brain model and supported by a neck model. The gel brain model in both the experimental studies was generated using silicone gel (Sylgard-527). The effects of tested models locations and orientations with respect to the shock tube exit were investigated by measuring the generated pressure wave within the brain model and acceleration. The results revealed that the pressure waveform and acceleration outcomes were greatly affected by the tested model orientations and locations in relation to the path of shock wave propagation.