Introduction

When developing a design for a product it's important to step back and take a whole look at the process of production, shipping, use, and disposal. This is important to judge the viability of a design. For our design we reviewed the materials we intend to use and the manufacturing wastes we expect to see from our selected materials. We took apart what each material effect would be on the design to determine its viability.

Product strength

Wear over time

Shoes last on average 8 to 12 months

Nomex can last five years and be watched 125 times

Compression Strength

The average human weight on Earth is 136lbs and on the moon that would be 68/3lbs. At any point one shoe would hold the entire weight of the person. Our shoe has a surface area of around 32.24in^2. It will endure a max stress of 0.703psi which is 0.00484702MPa. Silicone has a compressive yield strength of 10-30MPa which yield strength is the amount of stress a material can withstand without permanently changing.

Material production

Silicone

Silicone is a synthetic elastic polymer and is made of silicon, carbon, hydrogen, and oxygen. The production starts by isolating silicon by heating up ground quartz to 1800 degrees. This silicon is then heated again with methyl chloride to make methyl chlorosilane. Methyl chlorosilane is made of dimethyldichlorosilane which is the main part of silicone. The other parts of methyl chlorosilane is removed until only a dimethyldichlorosilane remains by boiling the other material away. Water is added to the dimethyldichlorosilane to split it into disilanol and hydrochloric acid. These two substances react to form polydimethylsiloxane. Polydimethylsiloxane is then polymerized into silicone.

Nomex

Nomex is a synthetic aromatic polyamide polymer based off m-phenylenediamine. It is made by creating a polymer is then spun and made into a fiber. That fiber is then woven into a fabric. The polymer that nomex is created from "can be obtained from the reduction of P-nitroaniline via iron in acid medium." (Chemical Book)

Environmental Impact

Silicone

Silicone is recyclable however the process to do so is complex so most people just throw it away. When recycled it can be turned into playground mulch, lubricants, or other products. Silicone doesn't biodegrade or break into small pieces, making it harder to be ingested by animals. Silicone can also be made from quartz sand instead of oil, making it more environmentally friendly than plastics. However the process of making silicone uses hydrocarbons to heat it up.

Production

Shoe production has a sizable carbon footprint. Sneakers account for 1.4% of global greenhouse gas emissions. For perspective, all air travel makes up 2.5% of global greenhouse gas emissions. Most of this comes from plastic inside shoes. Silicone doesn't create as much carbon dioxide as petroleum based polymers, however it is still used in its production.

Products Anticipated Lifecycle

Codes and Regulations

Shoe regulations -

COF for Earth 0.5 OSHA suggested

Fabric must not be flammable being better than class 1 flammability requirement of burn time of 7 seconds. This is a NASA safety protocol to prevent fires in space.

Cost

Each pair of shoes need 451sqin of Nomex which would cost $5.43. Each pair of shoes need 115sqin of silicone which would cost $9.58. Each pair of shoe would need 4ft of velcro which would cost $2.76. Each pair of shoes needs thread which would cost $9.99. Each shoes need glue which would cost $35.50. The shoe would in total cost $63.26.

Design viability

Our shoe design utilizes rubber, glue, stitching, Velcro, neoprene, and fabric. The rubber selected will have a high friction coefficient with the ground. This is important because the whole purpose of the shoe is to have a high coefficient of friction. This rubber sole will keep astronauts anchored to the floor with more control over their momentum. Our design is viable because these shoes use the sole as a friction surface and glue and stitching to hold our fabric foothold to the sole. This allows the shoe to be very durable for the harsh work conditions in the habitat and to function properly. The comfort sole shape will help make the sole more fitting to the foot to allow better grip on the inside of the shoe. The glue used will be heavy duty to hold the sole to the fabric exterior of the shoe.

Ethical Justification

Our shoes' negative drawbacks in production by using hydrocarbons to produce rubber, and plastic for polyester and fabric is outweighed by our shoes' valuable use in action. Manufacturing a couple dozen pairs of shoes a year results in minimal emissions and environmental concern. The shoes meanwhile will be providing a valuable tool to astronauts in space, by allowing them to work more efficiently and safely while in a low gravity environment.

Conclusion

From this design viability test we did, we were able to take a step back and review each critical component of our lunar habitat shoe design. We were able to see the importance of specific materials where we previously would have generalized. For example we spent time researching which fabrics would best suit the shoe design. We had constraints that we had to meet that limited our considerations, like price, Nomex is just too expensive for us to feasibly obtain so we choose a heavy woven fabric. We also found components that we decided to cut from the design, like the idea of using adhesive on the bottom of the shoes due the idea not being viable for a final design.

Sources (APA)

Picture Citation

Shoe assembly - youtube. (n.d.). Retrieved December 2, 2021, from https://www.youtube.com/watch?v=qbWlPevtVQM.

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