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Crash safety is a changing area in which safety requirements are updated or added from time to time. A relatively recent federal safety requirement is the amended FMVSS 201 rule for upper interior head impact. The automotive crash safety engineer faces many challenges in designing for this safety criterion. In the current study, it is shown how finite element-based simulation can be used as an effective tool in the design of lightweight headform impact protection countermeasures, supplemented with selective laboratory testing. Additionally, judicious employment of component finite element models and laboratory tests before a new countermeasure concept is deployed in a full vehicle environment leads to robustness and efficiency in product development.

NHTSA is expected to publish a final rule on Interior Head Impact (as an amendment to FMVSS 201) by early 1995. One of the Interior Head Impact Study objectives is to develop a methodology for estimating the minimum head impact space requirements to meet this regulation. The physical parameters affecting the HIC (Head Injury Criterion) are impact velocity, maximum headform stopping distance, peak deceleration, and pulse duration. The equations for estimating the HIC vs. Head Impact Space Requirements are formulated by relating these physical parameters to the Idealized Waveforms of Square Wave, Sine Wave, and Haversine Wave. This methodology has been extended to include the Generic Waveform. Tabulations of Maximum Headform Stopping Distance Requirement vs. Peak Deceleration, Pulse Duration, and HIC for the three Idealized Waveforms at 6.7 m/s (15 mph) impact speed have been generated to provide an estimate of the head impact package space requirement.