Evaluation of head tolerance to sagital impact by head acceleration and duration, and head velocity.

Impacts were imposed by three different methods on heads of monkeys. The difference in the head injuries produced are discussed in relation to the impact conditions and the relation between the impact conditions and head injuries produced is investigated. The threshold for the occurrence of concussion in the monkey is represented by the amplitude and duration of an imposed head acceleration. The human tolerance is estimated by dimensional analysis based on values obtained in the monkeys.