The head injury problem was investigated by the finite element method. The investigation started with a 2-D analysis and extended to a 3-D modeling. The 2-D models simulated a coronal section of the human head. The 2-D results provided insight into the coup-contrecoup injury mechanism and model parameters for 3-D analysis. The 3-D model represented an average adult male head. It simulated the essential anatomical features of the human head. The model included the scalp, a three-layered skull, i.e., the outer table, diploe, and inner table, the dura mater, falx cerebri, tentorium cerebelli, cerebral spinal fluid, longitudinal and transverse sinuses, left and right hemispheres, cerebellum, spinal cord and neck.
The finite element head model was impacted by a rigid cylinder to simulate cadaver tests by Nahum et al (1977). Model responses were compared with published cadaveric test data in terms of intracranial pressure in five locations, contact force, and head acceleration at the center of gravity in a direct impact situation. These responses showed a good agreement with those observed in cadaveric experiments and ensured the accuracy of the model.
Following model validation, parametric studies were conducted by varying the impact velocity, impactor mass, impact location, and the material properties of head tissues. Head response to an angular acceleration pulse was also simulated. The results of these studies provided further information for the interpretation of head injury mechanism and further modeling effort.
Head injuries were predicted by the output of time history and spatial distribution of skull stresses, intracranial pressures, and brain strains. Skull fracture, coup-contrecoup injury, diffuse axonal injury were predicted by locating the maximum stresses and strains in the head. Head injury criterion (HIC) was also computed as an injury indicator. The model was able to predict skull fracture, coup-contrecoup injuries, diffuse axonal injury in the direct impact situation and could be used to study head response to an indirect impact.