Effects of Multiple Impacts on Head Injury Criteria

Federal motor vehicle safety standard (FMVSS) 201 [1] stipulates that tests have to be conducted on the upper interior of vehicles to estimate the head injury criteria (HIC) and comply with the requirements of limiting the HIC(d) value to be less than 1000. Multiple impacts at the same location may lead to high values in HIC(d) due to strain hardening of the sheet metal. HIC(d) value is not only dependent on the performance of the countermeasure, but also on the performance of sheet metal underneath the countermeasure. This paper addresses the effect of multiple impacts on the HIC(d) value using finite element analysis. One of the objectives of this paper is to bring awareness of the effect of multiple impacts on head impact performance among the test engineers. A systematic procedure is established to decide vehicle structure change during development testing.