School of Engineering


Master of Science in Engineering


Hector Medina


pumped-storage hydropower, urethane-coated nylon, polymer-coated fabric, polyurethane degradation, fluid-storage, membrane tank


Mechanical Engineering


Polymer-coated fabrics are used for many fuel and water storage applications, such as in U.S. military field operations. Urethane-double-coated nylon (UDCN) is one such material used in collapsible fluid storage tanks. Research into the mechanical properties of UDCN membranes under different environmental conditions is necessary for substantiating its current operations as well as developing new technologies. Novel modular, closed-loop and scalable pumped-storage hydropower (PSH) systems are one technology that could use UDCN membrane tanks in order to mitigate large costs, risks, environmental impacts, and time-for deployment associated with PSH system construction due to their modular, closed-loop technology. This study focuses on the mechanical testing of UDCN membranes and similar polymer-coated fabrics to observe their hyperelastic behavior and the effects of UV irradiation and hydrolysis on the membranes. Additional testing included creep testing of UDCN membranes to characterize the longevity and viscoelasticity of the material. A UDCN membrane tank was also used in a lab-scale PSH loop system to verify UDCN membrane material performance. The numerical solution for a mathematical model for membrane tanks was then developed in Python and calibrated using experimental data from the PSH loop system. Results from this study indicate that UDCN membranes are viable for use in developing PSH technologies due to the low stresses seen by UDCN membrane tanks during use as well as the durability of UDCN membranes under UV and hydrolytic degradation conditions.