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Alan Salas, Kevin Dahms, Jess Zarker, Jose Ordonez, Robbie Moss ENGS 171 Industrial Ecology Redesigning the Bicycle
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Recap from last time
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Part 2: Redesign
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Design Requirements Seat Mast Tube FUNCTION: To support the weight of the person. Acts as a column in compression OBJECTIVES: Ideally, minimize environmental impact and mass CONSTRAINTS: Recyclable High strength and stiffness FREE VARIABLES: Material choice, shape, color
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Indices For minimizing environmental impact (embodied energy and CO 2 ) Minimizing Embodied Energy Minimize H m ρ/ E 1/2 for stiffness Minimize H m ρ/ σ y for strength Minimizing CO 2 Minimize CO 2 ρ/ E 1/2 for stiffness Minimize CO 2 ρ/ σ y for strength
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Indices for other components PartConfigurationFunction(s)Constraint(s)Objective(s) Fork 1 Beam (loaded in bending) 2 Columns (in compression) Provide support; link between handlebar and front wheel High stiffness, high strength Minimize: mass, embodied energy, carbon emissions Frame 6 Beams (loaded in bending) 1 Column (in compression) Provide structural support for bike Handlebar 1 Beam (loaded in bending) 1 Column (in compression) Give direction, provide stability, support part of rider's weight, platform for break handles Seat Mast Tube 1 Column (in compression) Support rider's weight
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Indices for other components
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Material Selection Analysis for seat mast tube (modeled as a column)
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Material Selection Bamboo! Low-alloy steel Lower embodied energy!
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Material Selection Bamboo! Low-alloy steel Lower CO 2
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Material Selection Bamboo! Lower density Low-alloy steel
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Trade-off Strategies
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Mass vs. Cost Bamboo, Softwood and Hardwood Low- alloy steel Cheaper
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Mass vs. Embodied Energy Bamboo, Softwood and Hardwood Low- alloy steel Less embodied energy
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Cost vs. CO 2 Bamboo, Softwood and Hardwood Low-alloy steel Less CO 2
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Cost vs. Embodied Energy Bamboo, Softwood and Hardwood Low-alloy steel Less embodied energy
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Shape 29 mm 38 mm 4.5 mm
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Shape -These specifications are for Iron bamboo, which is the strongest type -If it is a more flexible bamboo, use wider and thicker tubing -If internal diameter is less than 29 mm, there will be a hoop stress, which we didn’t look into carefully in this analysis. http://www.useful-arts.com/sua/instructions/bamboobikekit/harvest/
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Use Phase Analysis Negligible environmental impact NEXT Bike Maintenance: paint, wheels, lost accessories, oil Once child grows, bike becomes obsolete
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Use Phase Analysis (cont.) BamBIKE: Introduce a service program Convert the product into a service Incentive: offer free repairs (only cost is purchasing the parts), offer discounts, etc. Return old bike, obtain new larger bike at a discount “If your child grows faster than bamboo, we have a solution for you!”
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Discussion of Redesign
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Frame
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Joints + bamboo
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Fork
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Handle bar
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Seat tube
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Eco-Audit of redesigned bike 34% reduction
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CO 2 of Entire process 40% reduction
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Specifically looking at components 75% reduction 87%
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CO 2 of materials 74% reduction 87%
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Water-audit of redesigned bike Why isn’t there a significant change???
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Economic Analysis Materials: Low alloy steel 0.89-0.93 USD/kg At 3.68 kg, price is $3.35 Bamboo 1.37-2.05 USD/kg At 0.4 kg, price is $0.82 BUT, labor is a problem: More labor intensive to assemble BamBIKE, so higher costs are associated This is why it is currently only offered to very specialized, high end consumers
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Economic Analysis CNN article published today about a bamboo bike company located in Zambia: http://edition.cnn.com/2012/05/31/business/bamboo-bicycles-zambia-zambikes/index.html?hpt=hp_c4 “Each frame takes between 40 and 60 man hours to make […] Every piece of bamboo is having different colors, different bend, so every frame is unique." That explains the high costs, and why these “high-end, lightweight bicycles” have “a price tag of around $900” and are “primarily aimed at the international market”.
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Considering Aesthetics: Paint and Plastics Aesthetics are a major feature refractive quality of paint, extra features (painted plastic), logo designs Aesthetics are also subjective; malleable Don’t outweigh the environmental impacts: Greenhouse gas emissions: VOCs, CO2, NOx, SOx, and PM Health Concerns for workers “Eco-Design” Water-based paint Water-based non-toxic wood varnish logo
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Conclusions and Recommendations Findings Bamboo is an appropriate substitute for steel Considerations Industrial infrastructure is currently nonexistent This is the foundation for a sustainable lifestyle Saving 91 MJ per bike means saving energy of 245 bananas per unit!!!
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There are other important benefits of bamboo that could be further exploited: “One of nature's fastest growing resources” “Has great shock absorbing abilities that contribute to a smooth and eco-friendly ride” http://edition.cnn.com/2012/05/31/business/bamboo-bicycles-zambia-zambikes/index.html?hpt=hp_c4 Conclusions and Recommendations
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Moving forward… Hemp Wood and ideally… DIAMOND!
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Questions?
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