FE Analysis on the Thermoforming Behaviour of Large Spherical PMMA Panelapplied in JUNO

Abstract Jiangmen Underground Neutrino Observation (JUNO) mainly focuses on determining neutrino mass hierarchy. The central detector is one of the keys to JUNO experiment, which is a spherical liquid scintillator detector with 20 kton target mass. The target vessel of the central detector is a huge acrylic vessel with a diameter of 35.4 m. Its construction will certainly face many enormous challenges and difficulties. This paper introduces the thermoforming process for huge acrylic spherical panel, which is a very important step in panel production. The effect of temperature on panel’s curvature during thermoforming is discussed. The temperature field and thermal deformation of the panel during thermoforming are analysed by finite element method. The temperature field affects the panel’s shape and cause its radius smaller than the thermoforming mold’s. The paper presents some suggestions on improving the shape of spherical panel. The temperature at concave and convex surfaces of panel should be controlled as equal as possible during thermoforming. The other method to get a spherical panel with design radius is increasing the forming mold’s radius appropriately.