Embedded Files
FINAL DESIGN
Structural Reinforcement Rings
The structural reinforcement rings are made up of five carbon fiber ring segments connected by 3D printed connection pieces. The completed ring has a mean diameter of 0.61 meters (2 feet), the same as the chamber diameter. The segmented design was chosen for ease of installation and replaceability in the case that a segment should break. Additionally, the material choice of carbon fiber was chosen for its high strength to weight ratio compared to our initial material choice of steel. The ring segments were fabricated by the team by sliding two layers of 12.7mm (0.5 inch) inner diameter carbon fiber woven sleeves over 12.7mm (0.5 inch) diameter insulation foam rods. The segments were then brushed with epoxy, placed in a curing frame to ensure consistent shape, and left to cure for 48 hours. When installed in the chamber, the rings prevent the chamber from deforming radially which allows the device to achieve a higher maximum negative pressure.
Fully Assembled Reinforcement Ring
Pro/Con Table for Reinforcement Ring Material Choice
Waistband Seal Support Belt
The waistband seal support belt is a customized belt made from an off-the-shelf elastic velcro back support strap. Modifications were made to the belt in order to allow it to push the neoprene waistband of the device more firmly against the skin of the lower back. A cloth pouch was sewn onto the inner side of the belt at the lower back area. For the purposes of testing, a closed-cell foam half-cylinder was placed in the pouch. However, the belt was designed with modularity as a prime consideration, so the pouch is open on one end to allow for material changes. Additional modularity is achieved due to the elastic nature of the belt and the full - circumference velcro which accommodates for a large range of waist sizes. Our initial choice of using a diving belt rather than the elastic velcro strap was not able to achieve such modularity. Using the support belt in conjunction with the existing neoprene waistband of the device, the rate of pressure leakage from the chamber was significantly reduced during low-pressure tests.
Customized Waistband Seal Support Belt
Pro/Con Table for Belt Choice
Summary of Final Performance Results
The maximum negative pressure achieved by the final device was 23.5 mmHg.
The device was able to sustain its negative pressure above 10 mmHg for approximately 1 minute
Plots of Negative Pressure in the Device Chamber for All Prototypes
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