Mechanical and fatigue performance of pressurized vessels fabricated with Multi Jet Fusion™ for automotive applications

Abstract Multi Jet Fusion™ (MJF) is a new proprietary form of Additive Manufacturing (AM) from Hewlett Packard (HP) developed to manufacture structures with design and functional complexity while simultaneously providing a dramatic increase in the production rate relative to other forms of polymer-based AM. The increased rate is now enabling more efficient production of mid-volume products, and coupled with the additional benefits of geometric freedom, the technology is particularly well suited for the fabrication of complex manifold gas delivery systems. This paper describes a comprehensive study to evaluate the utility of MJF structures for maintaining pressures under static and dynamic conditions. The static pressure and gas confinement was applied to cylindrical structures at 345 and 689 kPa and pressure drops were measured in real-time. Similarly, fatigue pressure testing was performed for 105 cycles under 1724 kPa, and the cylinders demonstrated to be effective at maintaining a constant pressure under both ambient and high temperature (90 oC) conditions. Additional analyses relevant to the automotive industry were performed and included (a) gas permeation testing conducted with oxygen and carbon dioxide gas to study the gas storage performance on printed Polyamide-12 and (b) an oil chemical exposure experiment was performed to investigate mechanical performance degradation.