What is the EPS liner and why is it important?

In-depth explanation

EPS (expanded polystyrene) is the foam liner inside helmets that absorbs impact energy by crushing and dispersing force during a crash. It is critical because it reduces the peak acceleration transferred to the skull and brain. EPS is single-use for impact absorption; once compressed in a crash it cannot spring back and must be replaced (or the helmet replaced). Proper EPS thickness, density, and layering are important design choices for energy management across different impact speeds.

Key takeaways

• EPS (expanded polystyrene) is the foam liner inside helmets that absorbs impact energy by crushing and dispersing force during a crash.
• It is critical because it reduces the peak acceleration transferred to the skull and brain.
• EPS is single-use for impact absorption; once compressed in a crash it cannot spring back and must be replaced (or the helmet replaced).

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