Mathematical models of head injury: a ranking experiment

The injury criterion currently used to evaluate industrial safety helmets has no biomechanical justification. Seven available injury criteria, proposed during the 1960s and early 1970s, are discussed as possible replacements for the existing criterion. Each criterion was exposed to the broadest possible spectrum of test results that could be expected from industrial safety helmets. A wide variety of input accelerations were obtained from tests on 26 different helmets. A rank ordering of helmets was developed for each criterion and compared with those of the other criteria. Significant differences in rank ordering were noted among criteria. The Peak Acceleration Criterion, Gadd Severity Index, Head Injury Criterion, and Mean Strain Criterion, all generated similar rank ordering, but differences exist. The Mean Strain Criterion is recommended for industrial safety helmet performance evaluation.