In order to understand how to use online 3D modeling, our group was tasked with creating a digital helmet on Fusion 360. This is going to help us create a model for our product in the future.
Research
Why Helmet’s save our lives?
Describe how helmets provide impact protection by dissipating crash energy
Explain Newton 2nd Law of Motion
Calculate impact force
Design Sketches:
Research
Why Helmet’s save our lives?
- The helmet protects drivers from impact and allows them to communicate via radio with their crew. They are designed to have a hard outer shell and an inner layer of special crushable foam. Both of these layers help disperse the crash energy and protect the brain. Just imagine, most race car drivers are reaching speeds of over 200 miles per hour, resulting in impact reaching 50 to 100 Gs. At those G's, a helmet is your best friend
- It protects you from injuries such as skull fractures as well as moderate to severe brain injuries such as focal contusions and hemorrhages.
Describe how helmets provide impact protection by dissipating crash energy
- Helmets designed to handle major crash energy generally contain a layer of crushable foam. When you crash and hit a hard surface, the foam part of a helmet crushes, controlling the crash energy and extending your head's stopping time by about six thousandths of a second (6 ms) to reduce the peak impact to the brain. Rotational forces and internal strains are likely to be reduced by the crushing.
- When you crash, the point of a helmet is to do two things 1) protect you from a sharp object "high PSI" that could cause a piercing/cracking of the skull bone 2) protect you from a flat object "low PSI" that could cause neck fractures or brain trauma. The means by which this is achieved for either situation is simple...dissipate kinetic energy, i.e. take the newton force created by the impact and move it somewhere that is not your brain/skull/neck. To obtain objective #1 your need a hard outer shell and for objective #2 you need some sort of thicker barrier (foam) to transfer the energy away.
- So in an optimal situation, in a crash you want your helmet to absorb/dissipate as much kinetic energy as possible upon impact. According to the law of conservation of energy, the energy dissipated has to go "somewhere." In the case of a single impact helmet the energy goes into the EPS foam which causes it some degree of stress and str
- The typical helmet has a comfort liner, an impact energy attenuating liner, a restraint system, and a shell.
Explain Newton 2nd Law of Motion
- Newton's second law of motion can be formally stated as follows: The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.
Calculate impact force
- Impact Force(F): (2 mv)/t
- m= mass (0.680389kg)
- v= velocity at impact (26.8224m/s)
- t= Time Contact during Impact(t) 1sec
- (2(0.680389kg) (26.8224m/s)) / 1 sec
- 36.499 N
- Eventually, friction and gravity will work together to stop the motion of the slide. Gravity is a force that pulls two objects toward each other because of their mass. ... Balanced forces - Two or more opposite forces are balanced forces if their effects cancel each other and do not cause a change in an object's motion.
- The force of friction acts in the opposite direction of the motion. Rougher surfaces produce greater friction than smooth surfaces. Gravity is a noncontact attractive force that exists between all objects that have mass. Gravitational force depends on the mass of the objects and the distance between them.
- You need a full visor and a neck strap to fully fasten the helmet because a conditional logistic regression analysis showed that compared with helmeted motorcyclists, non-helmeted motorcyclists were more than four times as likely to have head injuries [odds ratio (OR) 4.54; 95% confidence interval (CI) 1.25–16.5] and ten times as likely to have brain injuries (OR 10.4; 95% CI 1.82–59.2). Compared with motorcyclists wearing full-face helmets, those wearing half-coverage helmets were more than twice as likely to have head injuries (OR 2.57; 95% CI 1.50–4.40) and brain injuries (OR 2.10; 95% CI 1.01–4.38). Compared with motorcyclists with firmly fastened helmets, those with loosely fastened helmets increased their risk of head injury (OR 1.94; 95% CI 1.33–2.82) and were more than twice as likely to have brain injuries (OR 2.50; 95% CI 1.47–4.25).
- Our helmet is pointed a little at the end to be more aerodynamic.
- CRUMPLE ZONES are areas of an object designed to deform and crumple in an impact, as a means to absorb the energy of a collision. The fronts of most automobiles are designed as crumple zones to protect the passengers from frontal collisions.
- The Shell: The outer shell of the motorcycle helmet can be made of fiber, plastic, carbon fiber, Kevlar, or the tri-composite of the three. The shell is designed for durability. Its primary goal is to protect your head in any event of crash or impact. It also protects the EPS lining.
- EPS Lining: The next protective layer of the helmet that is located beneath the helmet shell is the EPS or the Expanded Polystyrene Foam lining. This lining absorbs energy in case there is an impact. It redistributes the impact on the bigger area this lessens the impact on the skull. It also limits the full force on the skull and ventilates the head.
- Inner Lining: The inner lining provides comfort. It consists of a lining for the upper head area and the two cheek pads. Some of the inner linings of the modern helmets are removable and washable. Some have fabrics and anti-allergenic properties.
- Safety Standards
- Rigid outer shell to stop head from colliding with the ground
- An inner liner that is thick and soft to absorb impact
- Padding: To protect the head and reduce impact
- Visor/face shield: so the rider can see
- Ventilation system: so the rider can breathe
- Retention system (chin strap)
- https://helmets.org/general.htm
- https://academic.oup.com/ije/article/40/3/794/746475
- https://forums.mtbr.com/downhill-freeride/helmet-discussion-single-vs-multi-impact-733522.html
- https://www.physicsclassroom.com/class/newtlaws/Lesson-3/Newton-s-Second-Law
- https://calculator.tutorvista.com/impact-force-calculator.html
- http://s7d2.scene7.com/is/content/Caterpillar/C10332038
- https://motorcycleroom.com/the-basic-construction-of-a-motorcycle-helmet/
Design Sketches:
Finished Product: