AO4ELT5 Proceedings

Multiphysics dynamic simulation of the E-ELT M4 adaptive mirror during earthquake

Manetti, Mauro (Microgate), Tintori, Matteo (ADS International), Biasi, Roberto (Microgate), Mantegazza, Marco (ADS International)

Most of the future extremely large telescopes will be build in seismic areas, heavily affected by earthquakes. For example, the E-ELT is located at Cerro Armazones, in Chile, where earthquakes, also with high magnitudes, are a well known reality. This is the reason why the telescope, together with all its instruments and facilities, is required to survive seismic events. This paper is focused on the dynamic simulation of the E-ELT M4 adaptive mirror during earthquake. The M4 adaptive mirror is actuated through a contact-less technology based on voice coil motors and the mirror is restrained to the telescope only through a membrane. The mebrane provides by design a soft constraint with respect to the mirorr piston movement and tip/tilt rotations to allow the shell deformation. On the contrary, the in-plane displacements and the rotation around the axis normal to the reflective surface are well restrained by the membrane, which is designed to survive earthquakes. So, during seismic activity, the voice coil motors must provide a sufficiently strong force to avoid any possible shell detachment along the direction normal to the mirror itself, even wehn the shell is not actively controlled in position. The present work shows the development of a multiphysics simulator, which is able to reproduce the shell dynamic behavior along its normal direction during earthquake, so that appropriate levels of forces provided by the actuators and appropriate system safety strategies can be designed as function of the earthquake intensity.

DOI: 10.26698/AO4ELT5.0122- Proceeding PDF

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