A series of 34 side impact tests conducted using Post Mortem Human Subjects (PMHS) in a Heidelberg type sled, were examined for the purpose of developing and assessing thoracic injury criteria for side impact. The effects of three test conditions were investigated: test speed (24 or 32 kph), impact surface (padded or rigid), and pelvic offset (present or absent). Rib fractures were the most common injury type with injury severity ranging from Abbreviated Injury Scale (AIS) = 0 to AIS = 5. The test data were analysed using various statistical techniques. Several existing candidates for side impact injury criteria were evaluated, such as: Thoracic Trauma Index (TTI), Average Spinal Acceleration (ASA), chest deflection, chest velocity, chest Viscous Criterion (VC), peak and average contact force, Stored Energy Criteria (SEC) and Energy Storing Rate Criteria (ESRC) for their injury prediction ability. The analyses showed, among other things, that: the age of the subject influenced injury severity while gender and mass had little or no influence on injury response; maximum normalised chest deflection (dmaxn) was a better predictor of rib fractures and injury severity than any other existing injury criteria with TTI being the next best predictor of injury severity based on AIS; maximum normalised resultant upper spine acceleration (rspu180n) was the best individual predictor of injury severity based on rib fractures and maximum AIS levels; and that a model using a linear combination of age, dmaxn, and rspu180n was a significantly better predictor of rib fractures and injury based on AIS.
Abstract