Structural ropes development for the E-ELT structure

The European Extremely Large Telescope (E-ELT) structural rope system will be integrated in a mechanical structure, which can be made of mild steel and/or composite material. The following critical problems shall be solved by the rope system: matching of differential thermal expansion and tensioning forces calibration and control. The structural rope system consists of ropes, thermal compensation and tension control devices, and mechanical interfaces with the telescope structure. The objective of this study is to provide solutions to stabilize slender structural elements located in the upper part of the E-ELT Altitude Structure and increase global mode frequencies of the upper part of the E-ELT Altitude Structure. An appropriate rope system is developed to avoid local mode shapes and loss of stiffness that could lead to the failure of the whole structure under operational loads. The pre-tension level of the ropes needs to be controlled before operation to reach that objective.