Effects of Headform Friction on Ejection Mitigation Testing

Ejection Mitigation testing is now required by the U.S. government through FMVSS 226 [1]. FMVSS 226 contains the requirement of using a linear guided headform in a horizontal impact test into the inflated curtain, or other ejection mitigation countermeasure that deploys in the event of a rollover. The specification provides dimensions for a featureless headform [2] but there are limited specifications for the headform skin surface condition. In the “Response to Petitions” of the 2011 Final Rule for FMVSS 226 [3], the NHTSA declined the option to include a headform cleaning procedure. This research presents a case study to quantify the effect of changes in the friction between the headform and curtain on the measured excursion. The study presented here shows that a change in friction between the headform and curtain can affect excursion values by up to 135 millimeters (mm).