How was the PLEXIGLAS® viewing dome for Lula1000 made?
The requirements for the PLEXIGLAS® dome of the Lula1000 are easily summarized: The cockpit has to withstand the enormous pressure of deep water and be invisible under water.
As the submersible developer Joachim Jakobsen points out, the ultimate purpose is to send crews to explore the deep sea. "It is much easier to understand the complexity of the deep sea when you experience it with your own eyes. A video feed from a camera robot cannot compare."
Evonik had to find new work methods to accommodate the custom order. "The challenge was to turn a block of PLEXIGLAS® into a hemisphere without affecting the optical quality or impairing the material strength," explained Wolfgang Stuber, product manager in the Evonik Acrylic Polymers Business Line. The team therefore came up with a specialized process, in which an optically perfect, pre-approved block is reshaped with the help of heat and pressure. Germanische Lloyd, a globally recognized expert in the classification of ship, accompanied the development work and then certified the procedure. The new procedure stands out for its reliable production technology and high end-product quality. "The patent application is pending," reports Stuber. He is proud that Evonik once again showed its prowess as a development partner and solution provider.
The cockpit for Lula1000 required a 1,000 kg block. The thinnest section of the finished viewing dome has a thickness of 14 centimeters. The concave design allows for a viewing angle of 150 degrees. In deep water, the pressure on the cockpit is enormous. At a depth of 1,000 meters, there is a pressure of 1,000 tons on each square meter, the equivalent of 1,100 Smart cars stacked on top of a mid-sized flat TV screen. Glass would not be able to perform under these extreme conditions. The finishing work of the PLEXIGLAS® block was done by a specialty firm in Baden-Württemberg, which took care of grinding the cockpit.
The viewing dome of the Lula1000 has a diameter of approx. 1.40 meters. Another PLEXIGLAS® dome with a diameter of 61 centimeters seals the entry hatch at the top.
Jakobsen's experiences with other acrylic glass types were less positive. "We considered PLEXIGLAS® the top product in the market." The extraordinary light transmission was another plus. "When we dive down, we feel as though the dome is not even there."