Cheetah Flex-Foot® A Carbon Fiber – Reinforced Polymer Team RAMROD September 22, 2011

High performance prosthetic feet Designed to mimic the action of the anatomical foot Stores and releases energy produced by the user Made of Carbon Fiber Composites Comfort… power… agility…

Carbon Fiber Filaments Carbon fiber is produced through a polyacrylonitrile (PAN) precursor The carbon fibers can come out of three different spinning processes: wet, dry, and melt spinning The stabilization step of the fibers ensures sufficient cross-linking to be able to withstand the final heat treatment The end product is a highly advanced graphite composite material

Epoxy Epoxy is a highly versatile cross-linkable polymer for carbon fiber-epoxy composites The monomers making up the epoxy polymer must contain at least two strained-ring groups, called oxiranes The oxiranes contain one oxygen and two carbon atoms which able to be attached to a wide variety of organic molecules The properties of an epoxy, like adhesive strength and lifespan, can be greatly improved by a co-reaction with other specific compounds, most often multifunctional amines

Cheetah blades start as: Rolls of resin-impregnated carbon fiber The rolls are cut into square sheets Pressed onto the outside of a steel mold Milled in the shape of the legs’ final profile. Anywhere from 30 to 90 carbon-fiber sheets are layered one on top of another. The whole thing is swung into an Autoclave Melts and fuses the resin and sheets into a solid, contoured carbon-fiber plate. Once the compound cools, a robotic arm with a high- pressure water jet on the end carves the now curved sheet into several Cheetah legs

Bibliography “Applied Mechanics and Materials.” Trans Tech Publications 70 (2011): Carbon (fiber). (2011, September 21). In Wikipedia, The Free Encyclopedia. Retrieved 10:54, September 22, Manocha, L. M. "Carbon Fibers." Encyclopedia of Materials: Science and Technology. Ed. K. H. Buschow. Vol. 2. Kidlington, Oxford, UK: Elsevier Science, Print. Hodgkin, J. “Thermosets: Epoxies and Polyesters." Encyclopedia of Materials: Science and Technology. Ed. K. H. Buschow. Vol. 10. Kidlington, Oxford, UK: Elsevier Science, Print. "How Engineering has transformed Sport." Portia Ltd. Portia, Web. 22 Sep “Reinforced Plastics and Composites.” Sage Publications 30.9 (2011):

INGREDIENTS Solvents: water, hexylene glycol and benzyl alcohol Preservatives: cyclotetrasiloxane, imidazolidinyl urea, benzalkonium chloride Sodium chloride: increases viscosity of the product Benzyl alcohol: soothing agent which relieves irritation and pain Potassium phosphate: acts as a buffer to maintain a pH level close to 7.5; doesn’t irritate eyes Disodium EDTA: metal ion chelator; aids in cleaning skin and prevents metal deposits on the skin Poloxamer 184 (polyoxypropylene block polymer 184): a surfactant which helps reduce surface tensions; forms an emulsion with other ingredients and makes it easier to remove makeup and oil

Water: non-toxic (0) Cyclotetrasiloxane: low; irritant Sodium chloride: low; skin irritant (1) (LD50): 3000 mg/kg [Rat.]. Poloxamer 184: low (1) (LD50): 5000 mg/kg [Rat]. Imidazolidinyl urea: low; mild eye irritant; formaldehyde releaser (1) (LD50): >2250 mg/kg [Birds.]. Hexylene glycol: low/moderate; skin irritant (2) (LD50): 3097 mg/kg [Mouse]. Benzyl alcohol: moderate; hazardous by skin contact and ingestion (2) (LD50): 1040 mg/kg [Rabbit]. Disodium EDTA: low; skin/eye/respiratory tract irritant (2) (LD50): >2000 mg/kg [Rat]. Benzalkonium chloride: high; mutagenic (3) (LD50): 240 mg/kg [Rat].  LD50: Lethal Dose (50% of subjects died)