Thirty Meter Telescope enclosure production readiness overview

Michael Gedig; Walter Brzezik; Lisa Crofoot; Amir Hossein Hadi; Amin Kadivar; Tony Li; Sina Niaki; Colin Vincent; Mehdi Jalayer

doi:10.1117/12.2563253

13 December 2020 Thirty Meter Telescope enclosure production readiness overview

Michael Gedig, Walter Brzezik, Lisa Crofoot, Amir Hossein Hadi, Amin Kadivar, Tony Li, Sina Niaki, Colin Vincent, Mehdi Jalayer

Author Affiliations +

Proceedings Volume 11445, Ground-based and Airborne Telescopes VIII; 114450A (2020) https://doi.org/10.1117/12.2563253
Event: SPIE Astronomical Telescopes + Instrumentation, 2020, Online Only

Abstract

The enclosure for the Thirty Meter Telescope (TMT) uses a Calotte-style configuration, chosen for the advantages of a high degree of protection for the telescope, relatively low weight through the use of efficient shell structures, and a balanced shutter mechanical system. This design is unprecedented for large scale telescope enclosures, and introduces significant design, fabrication, construction and operation risks. This paper provides an overview of design development, analysis and testing work that was done to mitigate such risks. Compared to conventional enclosures, the combined moving mass of the cap and shutter represents a greater portion of the enclosure mass, increasing the risk of enclosure vibration impacts on telescope operation. The vibration risk was addressed through development of a self-steering bogie design, bogie spring design and testing, wheel and rail splice design and testing, and slow-speed motion simulation. Risks of rail damage at splices and bogie wheel bearing failures observed on existing observatories were also addressed by bogie and rail joint design. The bogie spring design and test program incorporated elastomeric materials that provide significant damping capability for structural seismic isolation while meeting bogie mechanical design requirements for load distribution and tracking. A novel approach to slow-speed rolling motion simulation in the stick-slip regime was developed with a view to better understand control and vibration impacts. A staged construction analysis and detailed installation sequence was completed, including falsework and erection aids. The activities described above have been performed as part of the recently completed Production Readiness design stage.

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Citation Download Citation

Michael Gedig, Walter Brzezik, Lisa Crofoot, Amir Hossein Hadi, Amin Kadivar, Tony Li, Sina Niaki, Colin Vincent, and Mehdi Jalayer "Thirty Meter Telescope enclosure production readiness overview", Proc. SPIE 11445, Ground-based and Airborne Telescopes VIII, 114450A (13 December 2020); https://doi.org/10.1117/12.2563253

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