How and When Blunt Injury Occurs — Implications to Frontal and Side Impact Protection 881714

The timing of liver laceration in swine during the course of a blunt impact was investigated. The swine were impacted on the upper abdomen by the lower segment of a steering wheel at 6, 9 and 12 m/s. The degree of compression in each impact was controlled independently from 10 to 50%. By varying when “the punch of an impact was pulled,” we reproduced progressive segments of a longer duration blunt impact. Autopsy of the subjects demonstrated that lacerations were initiated after 8 ms of loading at 9 m/s and 6 ms of loading at 12 m/s. The time of injury was concurrent with the time when the Viscous response exceeded a threshold of 1.2 m/s in our specimens. The Viscous injury criterion, defined as the peak Viscous response, was found to be the best predictor of liver laceration. We conclude that the Viscous response relates to the actual etiology of injury, in addition to being an excellent correlative measure. Our deduction of the timing of injury occurrence was confirmed by an analysis of published cadaver data where skeletal injuries can be observed. Field data of occupant injury in a side impact were re-examined in light of these findings to determine the optimal side impact protection. We found evidence that injury from both a high speed impact and from slower crushing is possible in a side crash. Our computer simulations also suggest that an anthropomorphic test device (ATD) with human-like compliance is necessary if laboratory test results are to reflect field performance.