A helmet is essential when we ride. Everyone knows that wearing a safety helmet can help us avoid injury in the event of an accident. So how does it protect us?
The protection effect of helmet on our head mainly depends on its strength. The so-called helmet is not the stronger, the better. Use your fist to press the helmet's inner buffer layer hard, and there should be a slight rebound feeling without pitting or falling chips, which is not hard. The high-quality sports helmet should be designed considerate enough in terms of damages during a collision. In a low-intensity crash, it is strong and will not break easily. In case it reaches a critical value (critical value is the degree to which the impact on the brain can cause brain damage in normal people) of the collision, the helmet is easy to break, relying on the force of the helmet rupture to reduce the energy of the cushioning blow to reduce the damage to the brain. Besides, the conversion curve for the critical value is very high.
Another critical point is the buffer against strong shocks. If the head falls on a sharp material in a crash, the impact at a point instantly reaches a very high level, and the helmet will begin to break at a certain point. But the direction of the force collapse is very important when it breaks. A poor-quality helmet is often perpendicular to the impact force, and it will collapse, which will also cause brain damage; when a good-quality helmet is subjected to a strong impact, the pressure will follow the helmet, diverging to both sides, which will have a large contact area after acting on the head and can effectively reduce the impact force and damage to the brain.
While the helmet protects us, it must also take into account whether it is comfortable to wear, and breathability plays an important role. Because 60% of the body heat is emitted from the head when wearing a helmet, the ventilation holes allow cold air to enter the helmet and exhaust the annoying heat; the more holes, the more detrimental to the strength of the helmet. A well-designed sports helmet will take both air permeability and strength into account.