Impact of internal pressure control during manufacturing on residual stresses and safety performance of type 4 pressure vessels

• Two functions of internal pressure were used during winding of ten type 4 cylinders • Using finite-element-analyses we show that the cylinders differ in residual stresses • All manufactured cylinders underwent slow burst tests to assess their performance • Strains were monitored during the slow burst tests using embedded optical fibers Composite pressure vessels are commonly manufactured using the wet filament winding process, where various process parameters can influence the performance of the finished component. In this study two designs of wet filament wound 6.8-liter type 4 composite pressure vessels were manufactured. Both differ only by the internal pressure used during the filament winding, which primarily influences the residual stress state in the composite structure. An extensive experimental study was carried out, including 10 slow burst tests and strain measurements with fiber optic sensors. Significant differences can be observed in the performance of the two designs even though the used stacking sequence, materials and other manufacturing parameters are the same for both designs. A discussion of the differences in the behavior of both cylinder types is provided, including the strain distribution in slow burst tests and failure mechanism.