Date of Award

5-8-2023

Degree Type

Capstone Project

First Advisor

Bahram Nassersharif

Abstract

Interest in lightweight composite overwrapped pressure vessels for military, aerospace and industrial sectors, just to name a few, has grown greatly in recent years. For the military and specifically the Naval Undersea Warfare Center, the main objective of the composite overwrapped pressure vessel is to replace the steel tanks that hold high pressure gasses in the new generation submarines to reduce overall weight of the submarine. The following analysis will show the development of a composite overwrapped pressure vessel using an aluminum liner from soda cans and a 90-0-90-0 overwrap of 2x2, 3,000 filament twill weave carbon fiber with an epoxy resin.

Initially, the Naval Undersea Warfare Center wanted our team to conduct a more research based approach to this design project. Asking us to more or less buy already made composite pressure vessels and conduct various tests on them. Some of these tests included shock testing, burst tests, impact tests, salt fog and crack propagation tests. We quickly figured out that with a budget of only one-thousand dollars, this was not feasible and also would not fulfill our task for our senior capstone class which was to end the year with a fully built and working prototype. In our case, a composite pressure vessel that would fit into our design specifications and match our engineering analysis based on those specifications.

We joined customer requirements from NUWC and engineering requirements to create some design specifications like a maximum length of 24 inches and a maximum weight of less than 4 pounds. We worked through our problem definition and moved to concept generation, Pugh Analysis and QFD Analysis. At the end of that, we were left with 120 concepts to sort through and find the best three that would fit our engineering and customer requirements. A final design was chosen with aluminum circular discs to avoid the costly process of wrapping hemispherical end caps like you would see on shell tanks.

In the spring 2023 semester the team was able to fabricate and test the COPVs. The liner of the COPVs was chosen to be a soda can, where the ends were cut off on the lathe using a razor blade. The soda can was then wrapped in carbon fiber twill, using epoxy and shrink wrap tape. The cans were then put in the oven for 2 hours at 250°F, and then cut down to size after the curing process. The end caps were fabricated from an aluminum cylinder. After cutting the end caps down to size, a center bore was created on both using a lathe. A gasket was then placed at the bottom of the bore, creating a face seal when fully assembled with threaded rods and locknuts. These COPVs then underwent burst testing, which involved filling and pressurizing the vessels with water until failure.

Comments

Team Name: Composite Group Inc. (Team 18)

Company Sponsor: Naval Undersea Warfare Center (NUWC)

Sponsor Representative: Greg Sisco

Document Reference: URI-MCE-402-18-2022

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