Composition of Motorcycle Helmets

Composition of motorcycle helmets
1. The shell is the first line of defense to absorb and disperse impact energy. The two main structures are fiberglass and polycarbonate. More specifically, the fiberglass shell can be made of any fiber-reinforced material, including fiberglass, carbon fiber, and aramid. Different materials are constructed in different sequences, resulting in thin and stiff shells. In these cases the shell can be made thicker or thinner by adding or subtracting layers of material. The composite shell is high density, which is why cheap helmets are made of polycarbonate plastic that peels. These shells are generally heavier than composite shells.
The shell will usually take small impacts, like falling from the seat while parking, without compromising your protection. Small bumps or scratches won't affect it. Anything more than a minor bump can cause invisible damage, so it's best to return your helmet to the factory for inspection before trusting it. Any impact strong enough will end the life of the helmet.
2. The buffer layer is composed of EPS (expanded polystyrene), usually several different densities sandwiched together to slow down the movement by deforming and absorbing shock. When the helmet is hit, the head inside is still moving until it hits the impact. While some certifications require the helmet to be hit multiple times in one place, once the expanded polystyrene is squeezed, it will not deform back to its original state and it will not provide the same level of protection again. If the helmet is hit hard enough to deform the padding, the helmet is unusable, but makes a nice lampshade.
3. The main job of the inner liner is to let the helmet wrap the head and prevent the head from shaking or rotating. It also has the effect of reducing noise inside the helmet, acting as a kind of barrier between you and the styrofoam, absorbing impact and the sweat and skin oils that can degrade the styrofoam. Good helmet with removable and washable comfort lining
4. The mask is obviously important, both to allow you to see the road and to prevent things from bouncing off the road and hitting you in the face. Good face shields are constructed of polycarbonate and tested for penetration resistance.
5. The retention system is fastened to the helmet and must undergo many tests to see how resistant it is when it is pulled out. There is no safety difference between a double D-ring and a ratchet or quick release, all types pass the test, but there are no springs and hinges on the D-ring. When the chin strap is buckled, the helmet must not be tilted forward and slip off the head.