Helmet-Mounted Displays: - USAARL - The - U.S. Army

Biodynamics 201
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Figure 7.9. Theoretical stopping distances for various G levels.
out” event is likely to occur, resulting in acceleration spikes being
transferred to the head. Energy liner “bottoming out” occurs when the
available crushing distance is exceeded and results in a rapid onset of the
measured acceleration level.
Contact area and impact surface shapes should also be considered since
they will help determine the load level required for the material to crush.
Head shapes typically result in large contact areas when the crown or side
region are impacted, and reduced areas when the forehead or rear regions
are impacted. To obtain the same energy absorption capability among the
various impact sites with a constant liner thickness, the crush load must be
increased for those impact sites with reduced surface areas.
For this reason, it is also important to consider the shape of the