How Does a Helmet Actually Work?

Before knowing how does a helmet work, let us try and understand what are helmets and why should we use a helmet.

Helmets are a safety gear  designed to protect our brain or head from injuries of an accident or a mishap. When there is a crash or an accident and you could do very less to prevent it from happening, a helmet can definitely help prevent or  minimize an injury to your head or brain.

It is impossible for any helmet to protect against all possible impacts. Even if it does, it is only limited to our head or brain which is covered and the rest of the body is still at risk. However, if there is a collision, wearing a helmet is definitely worth than not wearing it.

So how does a helmet work?

We all know that human brains can be injured by a severe collision or by an extremely violent rotation of head, wherein the brain remains stationary, giving the blood vessels or nerves a pull. So it is wise enough to use a helmet,  it atleast reduces the risk of a direct impact to the brain or head.

Helmets are designed to absorb most of the force of the impact during a collision, which in turn reduces the risk of a brain or a head injury.

To broadly summarize, helmets are designed to:

  1. Help the head slow down more leisurely
  2. Spread the impact of a thud or a plunge over a larger area

iii.      Avoid direct impact to the skull.

The helmets which are designed to sustain a collision, normally comprises of four parts: A firm outer shell, a crushable layer of foam, Chin straps and comfort padding.

The outer shell of the helmet prevent objects from penetrating and because they are hard, they spread the impact of collision around the entire helmet instead of having it focused at one point. The hard surface helps you skid on the road so that your neck does not get yanked.

This shell also helps to keep the crushable foam in one piece. Rounder helmets are considered safer as they can skid more easily. The layer of crushable foam is usually made up of expanded polystyrene.

When there is an accident and you hit against something rigid, the foam in the helmet crushes which in turn cushions the blow, absorbs the energy of the collision and hence minimises the impact on the brain.

Rotational forces or internal injuries are hence reduced by the crushable foam. Thicker the foam, it is better since it gives your head a better room.

However, if the foam is too thick, it will extend the outer circumference of the head in effect. So a super thick helmet will probably not serve the best.

The chin strap should be properly warped and adjusted along with the comfort padding which helps in keeping the helmet intact on your head during the crash.

The strap must be adjusted so that it does not slide to a side or back.

Helmets act as a shock absorber .When there is a fall or collision, there is a certain amount of speed in which the head is travelling. And since the head has some mass and it is moving, there is also an energy associated with it.

So when the helmet collides with an obstinate object, a wall, a vehicle or a ground, the rigid shell starts absorbing the energy generated by the falling helmet with the head inside.

The energy is then spread over a larger portion of the helmet, specifically, the internal foam layer.

When the skull inside the helmet strikes into the foam, it helps your head to slow down over a distance of a few centimetres. When the impact is over, the foam is left deformed, however the skull and brain are much better off. The crushing of the foam minimises the internal strains and rotational forces.

Thicker foam gives the head more space and more milliseconds to stop.  In short,  a helmet will effectively reduce the speed of the movement of the head, by breaking and crushing which in turn reduces the amount of impact energy transferred to the brain.

This whole course of action takes only milliseconds to turn a potentially fatal crash into a survivable one.

The foam present in some helmets are crushable but they do not ever recuperate. So if you ever bump a bike helmet which is made up of the customary expanded polystyrene foam, the foam is crushed and you can never use it again.

The helmets used for hockey or skateboarding has a rebound spongy foam called butyl nitrate foam or possibly expanded polypropylene foam. Any of these will restore their form slowly after a bump and can hence be reused.

Construction helmets are good enough as long as the shell is not wrecked and the suspension is intact.

Helmets which are designed for minor collisions do not essentially have foam inside. Some of them just have hard shells with a suspension head strap that helps the helmet to fit in properly and it also has some space inside for air circulation.

Usually helmets used for construction are of this type and do a fine job when a brick falls on your head or if you crash hard against a suspended steel beam.

It’s not advisable to use this while riding a bicycle, since if you fall off, they will not sustain the impact of falling on pathway.

Lastly, the most important aspect to be kept in mind is that a helmet should fit in properly. This prevents it from flying  in the air during an impact or a collision. So first, you should try a few helmets and pick one that you feel most warm and comfortable in.

Motorcycling, bicycling, racing or any sort of movements that involves speed, inflict risks of head injury leading to death or permanent disability. Helmets are the most proficient means of avoiding or minimising these injuries.

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