CLOSED FORM SOLUTION FOR FAILURE PRESSURE IN BEND-FREE PRESSURE VESSELS

Pressure vessels are widely used in many industries to store and transport liquids and gases. Among the growing body of research in the design of pressure vessels, a new bend-free concept has been devised that uses the benefits of composite materials to tailor the stiffness spatially through the structure using the variable angle tow (VAT) technique. Failure is an important factor in designing pressure vessels that should be predicted accurately in order to ensure a safe design. Previous failure analysis revealed excellent performance for the bend-free VAT design pressure vessel in comparison with isotropic and constant stiffness composite pressure vessels made of straight fibre trajectories. The feasible bend-free design space is sufficiently large to address other considerations while tailoring the stiffness of structures. However, research to date has not considered the failure load as a design parameter in the bend-free design methodology. In this study, a general analytical expression representing the failure pressure that is valid for all locations in the bend-free vessel is developed. This expression can be used to control the performance of the bend-free pressure vessel while tailoring the stiffness analytically without the need for further numerical analysis. Therefore, it is possible to select the fibre tow trajectory within the bend-free design space for each location in the structure, which has the best failure performance compared to other fibre tow trajectories that result in the bend-free state in structures.