Type V Pressure Vessel Design with Integrated Sheet Moulding Compound and Prepreg Bosses

State of the art Type V pressure vessel design utilizes metallic bosses for connecting the pressure vessel to surrounding structures and fluid systems. These metallic bosses add a significant mass to the overall weight of the structure. In addition, they impose the problem of a mismatch between the coefficient of thermal expansion between metal and CFRP, especially in cryogenic use cases. Therefore, replacing these metallic bosses with CFRP would increase pressure vessel performance. In this study, two different concepts of CFRP bosses are investigated. A Type V manufacturing concept is developed using towpreg-winding. First, a SMC boss design is investigated on a 1.2 L pressure vessel geometry. The performance of the SMC boss is compared to an aluminum boss manufactured with an identical tank layup. Burst pressure testing was carried out which proved the SMC design. Second, a prepreg boss is investigated on a 20 L pressure vessel geometry. The prepreg boss was manufactured using prepreg layers with different fiber orientations optimizing the mechanical performance of the boss. The weight performance was compared to a steel-boss. The results of this study proved the design of CFRP bosses by using SMC as well as prepreg-material for future pressure vessel concepts.