Predicting Head Injury Criterion in Real-World Frontal Impacts

Research on modeling head injury metrics and head acceleration waveforms from real-world collisions has been limited compared to vehicle crash pulses. Prior studies have used simple pulse functions to model vehicle crash pulses and have employed more complex approximations for head injury metrics. This study aimed to develop a method to predict 15 ms Head Injury Criterion (HIC15) in frontal passenger vehicle impacts using simple pulse functions, where only occupant peak head acceleration and head impact duration are known. Vehicle crash tests from the New Car Assessment Program (NCAP) were selected for frontal impacts that include driver occupants, then separated for training and testing. The resultant head acceleration-time curves of the driver Hybrid III 50th percentile male anthropomorphic test devices were collected. Rectangular, triangular, quadratic, half-sine, and half-haversine pulse functions were modeled using peak head acceleration and the duration of significant head acceleration from each training NCAP crash test. Duration ratios were values calculated to scale each pulse function in order to predict the same HIC15 as the driver’s experimental acceleration-time curve. Duration ratios were evaluated on each testing NCAP crash test by comparing the HIC15 predicted by each scaled pulse function against the driver’s HIC15. All five simple pulse functions generated from the model training NCAP tests had significantly different duration ratios. There were no significant differences in predicted HIC15 to the driver’s HIC15 from the model testing NCAP tests for all pulse functions. Findings indicate that applying the presented duration ratios to the five pulse functions can effectively predict HIC15 in frontal crashes similar to NCAP tests, making them useful tools when only peak head acceleration and head impact duration are known. This work will help biomechanical safety experts evaluate head injury risk when real-time occupant kinematics are not available.