Additive Manufacturing for Undersea Applications

Brian R. Said
Lockheed Martin Undersea Systems, Florida, United States

Keywords: CNC filament winding, additive manufacturing, advanced manufacturing, Ultem thermo plastic, carbon fiber thermo set vinylester, investment tooling

The Additive Composite Hybrid External Pressure Vessel is an alternative manufacturing concept process prototype for replacing machined pressure vessels for deep submergence applications. The hybrid materials approach includes aramid fiber filament (carbon fiber, etc.) wound over additively fabricated Ultem polyimide "preform" shapes that direct filament placement/lay-up in an external (male) open molding features with filament aligned via the CNC automated winding machine to precise anisotropic fiber orientations suitable to stress loading of structural containers exposed to external pressure fields. Structural details such as ribs, wall thickness and wall geometries as may be similar to alloy pressure vessels, but at significantly reduced cost, weight, capital tooling, and lead times. Additive Manufacturing components included the invested “preform” male mold fixture as well as re-useable tooling elements for creation of net shape end-cap sealing and clamping areas. The techniques are expected to produce end-products in substitute for Titanium 6-4 pressure vessels at 1/10th the cost and lead times (savings expected from a few thousand $ for smaller pressure vessels- to tens of thousands $ for larger pressure vessels), with applications from instrumentation housings, to submarine pressure hulls, to space craft tanks critical to exploration of Venus atmospheric pressure >1000psi