Key Concepts
ACCELERATION: a =v/t. Change in velocity over time due to an external or apparent force. (Gravity, Normal)
COEFFICIENT OF FRICTION The ratio of the frictional force to the Normal Force. μ = f/N, where μ is a ratio. (μ is pronounced "Myoo")
CRUMPLE ZONES: Areas of an object engineered to deform and crumple on impact to absorb the energy of a collision.
DRAG: Used in fluid dynamics as fluid resistance. Used in aeronautics as air resistance.
INERTIA: A physical state of motion that tends to stay unchanged when no forces are acting on the system
G FORCE: Force acting on a body as a result of acceleration or gravity. g = 9.8 m/s squared
FRICTION: A force contrary to the normal force when two objects or surfaces come in contact.
FORCE: Causes masses to accelerate; they are influences that cause a change of movement, direction, or shape. F=ma
KINETIC FRICTION: Occurs when two objects are moving relative to each other and rub together.
COEFFICIENT OF FRICTION The ratio of the frictional force to the Normal Force. μ = f/N, where μ is a ratio. (μ is pronounced "Myoo")
CRUMPLE ZONES: Areas of an object engineered to deform and crumple on impact to absorb the energy of a collision.
DRAG: Used in fluid dynamics as fluid resistance. Used in aeronautics as air resistance.
INERTIA: A physical state of motion that tends to stay unchanged when no forces are acting on the system
G FORCE: Force acting on a body as a result of acceleration or gravity. g = 9.8 m/s squared
FRICTION: A force contrary to the normal force when two objects or surfaces come in contact.
FORCE: Causes masses to accelerate; they are influences that cause a change of movement, direction, or shape. F=ma
KINETIC FRICTION: Occurs when two objects are moving relative to each other and rub together.
(above: Some initial sketches for what our helmet would look like)
Hard Hat Safety & Features
Our Hard Hat is outfitted with an adjustable strap that wraps around the forehead of the wearer. This adjustable strap allows for a broader consumer base, since small children and larger adults alike can utilize our product. This means companies can buy one set of safety gear to make sure everyone is safe in potentially dangerous situations.
The shock absorber springs located in between the strap and the shell put our helmet ahead of commercial designs in safety. To maximize safety, we are aiming to reduce the external forces on the wearer. Let's take a look at F=ma. In our crash simulation, m is always a constant, so the only option is to reduce Acceleration. a = v/t, so increasing the impact time decreases acceleration. Thus the shock absorber spring technology would decelerate a body headed to collision, exponentially reducing overall brain damage dealt.
In our design, the shock absorber springs themselves are important. There is an external latch on the outside of the helmet for clients to swap out damaged springs. These springs would also be sold separately with varying properties, so you can have the safest springs for the job. By manipulating the spring constant, we can either increase or decrease the friction of the spring. This is important because laws of Kinetic Friction states that Kinetic Energy in the face of an opposing force will convert to Thermal Energy. F=kx implies that the higher the value of the spring constant, more thermal energy is created while kinetic energy is converted. Consumers can analyze their degree of potential danger and customize the safety feature of the helmet to suit their physical situations.
In addition, our personalized helmet plans come equipped with a light and radio. These are recommended aesthetic customizations that we decided to add on to the design. A light would allow for hands-free illumination (necessary in mining) while the short wave radio could allow communication in case of emergency. The radio is facilitated by a square, radio-shaped holder on the right side of the helmet. At the bottom of the holder is a circular hole, where an earpiece can be plugged in to the radio. These technological components would be added to the versatile Underlay. The Underlay incorporates all equipment not adhered to the exoshell. This separation between the major components that make up our Hard Hat provides a Compression Zone. Using elasticity to our advantage the Underlay acts similarly to a Crumple Zone in a car. Our design draws many parallels with safe crumple zone engineering concepts.
The shock absorber springs located in between the strap and the shell put our helmet ahead of commercial designs in safety. To maximize safety, we are aiming to reduce the external forces on the wearer. Let's take a look at F=ma. In our crash simulation, m is always a constant, so the only option is to reduce Acceleration. a = v/t, so increasing the impact time decreases acceleration. Thus the shock absorber spring technology would decelerate a body headed to collision, exponentially reducing overall brain damage dealt.
In our design, the shock absorber springs themselves are important. There is an external latch on the outside of the helmet for clients to swap out damaged springs. These springs would also be sold separately with varying properties, so you can have the safest springs for the job. By manipulating the spring constant, we can either increase or decrease the friction of the spring. This is important because laws of Kinetic Friction states that Kinetic Energy in the face of an opposing force will convert to Thermal Energy. F=kx implies that the higher the value of the spring constant, more thermal energy is created while kinetic energy is converted. Consumers can analyze their degree of potential danger and customize the safety feature of the helmet to suit their physical situations.
In addition, our personalized helmet plans come equipped with a light and radio. These are recommended aesthetic customizations that we decided to add on to the design. A light would allow for hands-free illumination (necessary in mining) while the short wave radio could allow communication in case of emergency. The radio is facilitated by a square, radio-shaped holder on the right side of the helmet. At the bottom of the holder is a circular hole, where an earpiece can be plugged in to the radio. These technological components would be added to the versatile Underlay. The Underlay incorporates all equipment not adhered to the exoshell. This separation between the major components that make up our Hard Hat provides a Compression Zone. Using elasticity to our advantage the Underlay acts similarly to a Crumple Zone in a car. Our design draws many parallels with safe crumple zone engineering concepts.
(Left: A perspective view of our helmet. Right: Right, front, and topdown Orthogonal views of the hard hat.)
Research
In researching the physics behind helmet design, we learned the numerous aspects that go into the design of a helmet, in order to protect the user. What we found was surprising; construction helmets are very simplistic and lack the modern impact protection mechanisms that bike, skateboard, and motorcycle helmets contain. This is due to a lack of interest in the industry because large construction firms must purchase these safety devices, not individuals who put their own safety paramount, even if it costs them. But these workers safety is still vital. So we researched how the aforementioned helmets with impact protection actually achieve this goal. Most share a similar principle; a hard shell encases a layer of hard foam that will crush on impact. What this does is extend the impact time between your head and whatever surface or oncoming object is heading your way. We can easily see why this works by looking to the equation F=MA with force being F, M being mass, and A being acceleration. In order to minimize the impact, it would be logical that we would want to minimize F (force). To do this then, we would need to minimize either mass or acceleration. Since the mass of you or the object hitting you is constant, then it would only make sense that we would want to reduce acceleration. Once again, we can go to the old physic textbook to find the formula for acceleration: A=V/T. The two variables on the right side of the equation stand for change in velocity and change in time respectively. Once again, we find ourselves with one variable we can’t change (change in velocity), and one that we can (time). If we can increase the duration the head is impacted by the object, we can decrease the acceleration, thereby decreasing the force. This is the simple principle that helmets use to protect their users. Helmets normally do this by implementing hard foam that will crumple on impact. Ideally, this foam will be softer for a light impact and harder for a hard impact. Hard hats specifically have a couple of differences from other types of helmets. Firstly, they are less protective against impact, normally opting for an isolated headband that holds up a hard plastic shell. This is primarily because these hats are made to protect workers from any falling debris, not impact. But what we also found is this is also due to a simple lack of initiative from the companies that make these helmets. Ultimately, without these impact protection features, the workers well being is compromised. The sturdy outer shell we found was also very important. Unlike a motorcycle or bike helmet, hard hats must protect from sharp objects that may fall (think rebar, concrete, wood) so a sturdy shell is essential to make sure these objects do not pierce or indent the skull of the worker. Instead, the impact is distributed, lessening the pressure experienced on any one part of the skull. Given this, the material the shell is made of is vital to the design. What we found is that the material of choice in this application is a material known as high density polyethylene (HDPE). We found that this material is actually the most common plastic used in the united states, and for good reason. The material is strong, lightweight, malleable, impact resistant, long lasting, and resistant to wear. Because of this, we decided to stick to the industry standard in this case, simply because there is nothing to improve.
SOURCES:
http://www.honeywellsafety.com/fibre-metal/Head_Protection/?LangType=1033
https://www.plasticsmakeitpossible.com/about-plastics/types-of-plastics/professor-plastics-high-density-polyethylene-hdpe-so-popular/
http://zonalandeducation.com/mstm/physics/mechanics/forces/newton/mightyFEqMA/mightyFEqMA.html
http://www.physicsclassroom.com/class/1DKin/Lesson-1/Acceleration
https://www.helmets.org/general.htm
SOURCES:
http://www.honeywellsafety.com/fibre-metal/Head_Protection/?LangType=1033
https://www.plasticsmakeitpossible.com/about-plastics/types-of-plastics/professor-plastics-high-density-polyethylene-hdpe-so-popular/
http://zonalandeducation.com/mstm/physics/mechanics/forces/newton/mightyFEqMA/mightyFEqMA.html
http://www.physicsclassroom.com/class/1DKin/Lesson-1/Acceleration
https://www.helmets.org/general.htm
The Helmet Model
The model made to demonstrate our design can be found here. (To view it, you need to download the full file and open it with Fusion 360.)