Finite Element Simulation Study of Human Brain Safety Threshold Under Medium-Speed Collision Load

A high-fidelity finite element model of the human head was developed to investigate brain injury under medium-speed impact and to quantify impact conditions related to injury thresholds. The model was reconstructed from MRI data, and the coupled Eulerian-Lagrangian method was used to model the fluid-structure interaction of cerebrospinal fluid. A six-degree-of-freedom stiffness constraint was introduced for the atlantoaxial joint. After validation against the Nahum experiment, intracranial responses under frontal, occipital, vertex, and temporal impacts were compared. A three-factor, three-level response surface method was then applied to the most hazardous impact direction. The model showed good agreement with experimental results. The results showed that occipital impact indicated the greatest injury risk and that impact velocity was the dominant factor affecting injury response. Under m = 4 kg and S = 208 cm2, the critical velocities for 6 kPa von Mises stress, and 18% maximum principal strain were about 1.75 m/s and 4.0 m/s, respectively.