Design and optimisation of a type IV composite pressure vessel

Abstract

Due to an ever-growing demand for sustainable transportation, there is an increased need for the development of hydrogen as an energy carrier. Based on mass, hydrogen contains about three times as much energy as conventional gasoline. However, the volumetric energy density, which is the amount of energy per volume unity, is much lower for hydrogen. Therefore, it needs to be stored either at cryogenic temperatures or at hyperbaric pressure. The most common nominal working pressures (NWP) for hydrogen are either 350 or 700 bar. Because of these excessive pressures, the composite pressure vessels (CPVs) require to become thick-walled. This makes the out-of-plane stress components significant which requires calculation models that consider these effects.

This thesis evaluates, whether the use of tow-preg material, could reduce the amount of material necessary to attain a predefined burst pressure. Currently, the production of CPVs is mainly executed using wet winding. The use of this process results in varying material properties due to differences in fibre volume fraction. Also, the friction coefficient is minimal because the resin has a low tackiness. This friction is required for the production of winding paths, which deviate from the traditional geodesic angle. Alternatively, tow-preg material introduces constant material properties and possibly an elevated friction coefficient. This friction coefficient provides an opportunity to vary the winding angle through the thickness, by which the material strength can be made more uniform in every lamina. However, the challenge during the design and production of CPVs is that several effects are present which alter the mechanical response such as varying stiffness on the dome-cylinder interface, non-geodesic winding angle on the dome and resin-rich areas. This thesis will attempt to describe the mechanical behaviour of the CPV, by including several phenomena in numerical models and to minimise the material usage.