A simulation model for a telescope earthquake analysis: the VST primary mirror safety system
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The VST (VLT Survey Telescope) is a wide field survey telescope going to be commissioned at Cerro Paranal (Chile). Due to the geological nature of the area, telescopes in Chile can be submitted to unpredictable and sometimes severe earthquake conditions. The commonly used response spectrum analysis has proven to be not suitable to evaluate the behavior of the VST telescope during an earthquake, due to the high number of devices with a nonlinear force–displacement characteristic in the primary mirror cell. Therefore, a nonlinear transient analysis based on a mixed Finite Element-Simulink approach has been carried out. A linear Finite Element (FE) model of the telescope has been developed and exported to Simulink, using a space state model representation. Then all nonlinear devices have been properly modeled and artificial accelerograms based on seismic history of the site have been applied. The paper focuses on the Simulink model, while giving an overview of the whole procedure.
KeywordsTelescope Finite elements Earthquake analysis Matlab
The authors would like to thank Michael Müller and Franz Koch from the European Southern Observatory, who suggested to model telescope nonlinear elements inside Simulink and provided the software for the export of the telescope linear FE model to Simulink.
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