Semester

Spring

Date of Graduation

2009

Document Type

Dissertation

Degree Type

PhD

College

Statler College of Engineering and Mineral Resources

Department

Mechanical and Aerospace Engineering

Committee Chair

Samir N Shoukry

Abstract

The hydrogen economy envisioned in the future requires safe and efficient means of storing hydrogen fuel for either use on-board vehicles, delivery on mobile transportation systems or high-volume storage in stationary systems. Leading edge technologies are currently under development for storing hydrogen safely and efficiently on-board vehicles in the form of either compressed gas (CGH2), cryogenic liquid (LH2), or solid matter (SSH2). The main emphasis of this work is placed on the high pressure storing of gaseous hydrogen on-board vehicles.;As a result of its very low density, hydrogen gas has to be stored under very high pressure, ranging from 35 to 70 MPa for current systems, in order to achieve practical levels of energy density in terms of the amount of energy that can be stored in a tank of a given volume. The optimal design configuration of such high pressure storage tanks includes an inner liner used as a gas permeation barrier, geometrically optimized domes, inlet/outlet valves with minimum stress concentrations, and directionally tailored exterior reinforcement for high strength and stiffness. Filament winding of pressure vessels made of fiber composite materials is the most efficient manufacturing method for such high pressure hydrogen storage tanks. The complexity of the filament winding process in the dome region is characterized by continually changing the fiber orientation angle and the local thickness of the wall.;The research conducted for this dissertation reveals that the continuously changing angle orientation and local laminate thickness in the dome regions can be modeled by a unique approach that utilizes suitable transformations of the macromechanical composite properties and the local coordinate system. Accurate representation of the exterior reinforcement allows for detailed analysis of the dome structure as well as the nozzle/valve connection. A metallic insert is utilized to connect the dome structure to the valve system. A comparative study between different insert geometries and locations in the dome has been performed. It shows that an insert extending through the dome geometry increases the resulting stress at the cylinder-dome juncture. The most effective design approach entails an insert to the boss region.

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