Earlier studies have shown that braided material significantly improves the ballistic performance of COPVs, but the current effort is to see if the braid is also contributing to structural performance. The goal is to determine whether improved ultimate burst pressure and improved failure mode can be achieved without adding much cost and/or mass to the vessel or slowing down the manufacturing process.
Burst tests on a filament wound vessel result in
Braided fibers contain the failure mode.
The fabrication and testing of a series of COPVs with and without braided fibers added to the typically filament-wound structure, as seen in the pictures and video on this page, is demonstrating that braid can achieve these goals. This investigation is still ongoing, but tests indicate that braid can significantly improve the ultimate burst pressure of COPVs with minimal weight added and no burden to the manufacturing process. The failure mode is also spread out over a larger area in the cylindrical portion of the vessel and there is little fragmentation of the overwrap during burst.
The effects of the braid in the COPV are currently under study. It has been suggested that the braid contributes to the vessel in several ways: the braid provides support to the metal liner on its own, it helps make the neighboring filament wound layers more efficient in transferring their loads, and the braid provides fibers on the vessel in angles that are not commonly achieved by filament winding.