Design and Testing of a Composite Pressure Hull for Deep Autonomous Underwater Vehicles

Abstract

This paper presents the design and testing process of the hull of a deep small autonomous underwater vehicle, rated at 2000m depth. Starting from setting the geometrical constraints for the design to mass production. None of the previous literature, to the authors' knowledge has presented similar work. Carbon Fiber Reinforced Epoxy material was chosen given their high strength to weight ratio and similarity of its compressibility to sea water. Material characterization was performed to obtain the material properties under loading conditions using a modified method of the Combined Loading Compression testing technique. A specific fixture was designed and manufactured to test filament-wound tubes. An analytical model was developed on MATLAB, a finite element model was created on ABAQUS, and the results of both models were compared. Then a quality control set of tests was performed including seawater absorption under high pressure and void analysis using destructive and non-destructive tests. Pilot samples were manufactured and tested in a pressure vessel, where one was cycle tested and inspected using visual and ultrasonic testing, and the other one was fail tested where it failed at ~93% of the expected load.

Miniature Underwater Glider Hydrodynamic Performance

“…From equations (10)(11)(12), it is clear that the optimized angle of flight in terms of horizontal speed is not related to the hydrodynamic properties of the glider, whether lift or drag. Differentiating the horizontal speed with respect to the glide angle gives an optimal angle of approximately 35°, as shown in equation ( 13) [10].…”

“…The hull composes mainly of three parts. The first part is a pressure housing that is made from carbon fiber composites and hosts all the pressure-intolerant components such as batteries and electronic Printed Circuit Boards (PCBs) [11]. The other two parts are fairings, which are flooded and host the pressure-tolerant components that are subject to seawater such as external sensors.…”