Many people have played roller skating. When playing roller skating, they usually wear helmets. Why? Someone might say "protect your head". What role does the helmet play in protecting the head? Let's first understand the possible head injury in an accident.
When the body loses balance in roller skating, the head will fall to the ground at a certain speed. There are two situations when the head touches the ground: first, the head is pressed vertically to the ground, and the skin, bone and soft tissue of the head may be contused or torn, or even the bone may be broken, or the brain tissue may be damaged in severe cases; Second, when the head slides parallel to the ground, the force generated by the friction and collision between the body and the ground is transmitted to the head, which will lead to cervical spine injury. The safety helmet is designed to protect the head in case of impact during movement.
Generally speaking, the safety helmet consists of three main components: shell, buffer layer and wearing device (tether). They have the following protective effects: when the head collides with other objects (such as the ground), the energy generated by the impact is absorbed by the buffer layer; The shell with high outer hardness makes the contact point between the helmet and the impacted object slide to avoid excessive energy on the cervical spine; The wearing device is to ensure that the protective device is relatively fixed in the correct position of the head. If the impact energy is high, the helmet may break, but it can still reduce the energy transmitted to the head and avoid or reduce head injury.