Nonlinear transient survival level seismic finite element analysis of Magellan ground based telescope

Matt Griebel; Christine Buleri; Andrew Baylor; Steve Gunnels; Charlie Hull; Povilas Palunas; Mark Phillips

doi:10.1117/12.2230725

27 July 2016 Nonlinear transient survival level seismic finite element analysis of Magellan ground based telescope

Matt Griebel, Christine Buleri, Andrew Baylor, Steve Gunnels, Charlie Hull, Povilas Palunas, Mark Phillips

Proceedings Volume 9906, Ground-based and Airborne Telescopes VI; 99061N (2016) https://doi.org/10.1117/12.2230725
Event: SPIE Astronomical Telescopes + Instrumentation, 2016, Edinburgh, United Kingdom

Abstract

The Magellan Telescopes are a set of twin 6.5 meter ground based optical/near-IR telescopes operated by the Carnegie Institution for Science at the Las Campanas Observatory (LCO) in Chile. The primary mirrors are f/1.25 paraboloids made of borosilicate glass and a honeycomb structure. The secondary mirror provides both f/11 and f/5 focal lengths with two Nasmyth, three auxiliary, and a Cassegrain port on the optical support structure (OSS). The telescopes have been in operation since 2000 and have experienced several small earthquakes with no damage. Measurement of in situ response of the telescopes to seismic events showed significant dynamic amplification, however, the response of the telescopes to a survival level earthquake, including component level forces, displacements, accelerations, and stresses were unknown. The telescopes are supported with hydrostatic bearings that can lift up under high seismic loading, thus causing a nonlinear response. For this reason, the typical response spectrum analysis performed to analyze a survival level seismic earthquake is not sufficient in determining the true response of the structure. Therefore, a nonlinear transient finite element analysis (FEA) of the telescope structure was performed to assess high risk areas and develop acceleration responses for future instrument design. Several configurations were considered combining different installed components and altitude pointing directions. A description of the models, methodology, and results are presented.

Citation Download Citation

Matt Griebel, Christine Buleri, Andrew Baylor, Steve Gunnels, Charlie Hull, Povilas Palunas, and Mark Phillips "Nonlinear transient survival level seismic finite element analysis of Magellan ground based telescope", Proc. SPIE 9906, Ground-based and Airborne Telescopes VI, 99061N (27 July 2016); https://doi.org/10.1117/12.2230725

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