The Ability to Walk Across Water BY TREVOR WEEKS, JAIMING LIU, YOUSSEF ALI, JORDAN WOODWARD

Table of Contents Introduction Specifications and Target Audience Concept Generation and Evaluation Technical Analysis Development Testing

Gantt Chart

Our Mission and Problem Statements To effectively communicate in order to achieve long term goals Problem: To design, build and test an ergonomic device, such as a buoyant shoe, as well as market it to a large consumer base of young adults aged 16-25 years enabling them to walk across still or slow moving bodies of water ranging from pools and ponds to streams and lakes for recreational and transportational use while being user friendly all at an optimal cost.

Stakeholders? Possibly You!! Professor Classmates Angel Investors Landfill Operators The User

Importance of Dryness? (1 low / 10 high) Survey Results Interested? Gender? Age? Importance of Dryness? (1 low / 10 high)

Importance of Mobility? (1 low / 5 high) Survey Results Importance of Mobility? (1 low / 5 high) Life Expectancy? Amount of Use? Type of use?

Design Specifications 100-200 lbs of supported weight (Tester was at max weight) HIgh portability Easily mountable and demountable Strap mount fitting foot sizes to 15 (financial constraint: excluded in prototype) Lifespan of 1-3 years Durable: withstanding drops and normal wear and tear User must be able to swim (Indicated by safety warning on marketed product) Durability: withstand drops survive normal wear/tear water-proof Variety of colors Provides a safe experience for the user EPA and CPSC compliant: “consumer products safety standard described in section 7(a), 2056(a) “ (CPSC)^1 ISO certified: “customers are far more likely to contact a company if it uses an ISO 9001 logo in the marketing of its products or services” (ISO)^2

Potential Solutions Water bottles duct taped together Styrofoam shoes Wood foot canoes Hamster floating ball Self buoyant water skis Inner tube

Preliminary Design Sketches

Pairwise Component Comparison Comparing specs to determine relative importance

Concept Scoring Comparing each design in terms of their ability to meet design specs

Selected Design: Styrofoam Shoes

Polystyrene Shoes Physical Quantities <Product was re-dimensioned from these original dimensions per block

How the System Works User wears the product like shoes User walks with product like shoes poles are built in to provide user with assistance MENTION HOW SIMPLE IT IS!!!

Buoyancy Force Calculations Unknown Variables: density of the material volume covered by water ^1

Buoyancy Force and Differing Densities

Academic Reference “The deformation dependences of the shear stress obtained for these polymers became non-monotonic with rising deformation rates. This was characteristic of the reversible destruction of the polymer structure which increased with growing rates of shear. The maximum on the shear stress vs. deformation curve enabled the ultimate shear strength to be determined as a specific point on this curve. The ultimate shear strengths were reached at a deformations of several hundred percent, while steady flow conditions were attained at deformations of several thousand percent” ^3 (G. V. VINOGRADOV Institute of Petrochemical Synthesis of the Russian Academy of Sciences ) READ THIS AND NOT THE SLIDE: “in this quote by russian scientist Georgi Vinogradov, he explains how polymers, such polystyrene, are able to withstand shear force (stress) and melts (at high temperatures) little to no permanent deformation. (example: styrofoam is a great insulator of heat or cold) Compared to other polymers, polystyrene is fairly average in these categories

Young’s Modulus (elasticity) (makeitfrom) ^2 tyttt

Density and Cost Effectiveness ^3,^4

Tipping and Structural Engineering Object Static Stability depends on: The center of gravity (G), through which gravity exerts a downward force equal to the displacement of the object The center of buoyancy (B), being the center of the underwater volume of the object, whose upward thrust counteracts the effect of gravity acting through G The center of distance (Gz) between G and B (GZ curves)^4 ^5

Bill of Materials

CAD Sketches

First Completed Prototype

https://drive.google.com/open?id=0B_zOaLuuFZoyaDBaQ0czT1RzLVk First Trial Results https://drive.google.com/open?id=0B_zOaLuuFZoyaDBaQ0czT1RzLVk 00:45

Problems and Solutions Low Stability Water wrapped in bubble wrap PVC pipes to help walk across water Nowhere to secure feet for maximum stability Carve a place for the foot in each block

Conclusion We were able to complete walk across the pool successfully in 2:50 Minor improvements to be done in order to advance to production level

How we plan to sell the product Materials polystyrene protective hard coating Upgrades transportation handle removable supports Cost high volume = low cost Marketing coastal areas warm climates United States

References https://www.cpsc.gov/PageFiles/105435/cpsa.pdf https://www.isoqsltd.com/iso-certification/iso-9001-certification-quality-management-system/ Vinogradov, G. V. and Belkin, I. M. (1965), Elastic, strength, and viscous properties of polymer (polyethylene and polystyrene) melts. J. Polym. Sci. A Gen. Pap., 3: 917–932. doi:10.1002/pol.1965.100030307 http://www.sailboat-cruising.com/gz-curves.html

Image References http://byjus.com/physics/buoyancy/ http://www.makeitfrom.com/material-properties/Polystyrene-PS#Intro http://www-materials.eng.cam.ac.uk/mpsite/interactive_charts/stiffness-density/basic.html http://www-materials.eng.cam.ac.uk/mpsite/interactive_charts/stiffness-cost/basic.html http://www.sailboat-cruising.com/gz-curves.html

Questions?