Lessons learned from the Arecibo Observatory auxiliary M4N socket analysis and implications for future observatory designs

Pavel Babuska; Vinay Goyal; Gregory Harrigan; Kauser Imtiaz; Azita Valinia

doi:10.1117/12.2628737

25 August 2022 Lessons learned from the Arecibo Observatory auxiliary M4N socket analysis and implications for future observatory designs

Pavel Babuska, Vinay Goyal, Gregory Harrigan, Kauser Imtiaz, Azita Valinia

Author Affiliations +

Proceedings Volume 12186, Observatory Operations: Strategies, Processes, and Systems IX; 121861G (2022) https://doi.org/10.1117/12.2628737
Event: SPIE Astronomical Telescopes + Instrumentation, 2022, Montréal, Québec, Canada

Abstract

The Arecibo Observatory collapsed after a progressive structural failure originating from a single open socket joint. A failure investigation was conducted to identify the cause of the first failed cable termination socket. Due to the nature of the suspended observatory receiver, the dominant source of loading in the suspension cables was due to deadload, with secondary contributions coming from environmental effects and observatory operation. The high ratio of deadload vs. live load applied to the cable over many years resulted in a creep failure mode of the cast zinc within the socket which further induced stress into the highly stressed wires at the entrance of the socket. The design of the socket joint did not explicitly consider socket constituent stress margins and time-dependent damage mechanisms such as creep. Lessons learned from this investigation led to recommendations for revising civil engineering cable standards, and recommendations for manufacturers and designers. The design of cables employing socket terminations should consider the cumulative damage effects from creep and cyclic loading, identify their corresponding worst-case inspectable defects, or establish a sufficiently high factor of safety so that the design is sufficiently robust to defects and time-dependent failure modes. The design should specify end-of-life capability and set service life inspection intervals with pass/fail inspection criteria. Finally, trial studies on design iterations were conducted to increase the reliability of cables with socket joints.

Conference Presentation

Citation Download Citation

Pavel Babuska, Vinay Goyal, Gregory Harrigan, Kauser Imtiaz, and Azita Valinia "Lessons learned from the Arecibo Observatory auxiliary M4N socket analysis and implications for future observatory designs", Proc. SPIE 12186, Observatory Operations: Strategies, Processes, and Systems IX, 121861G (25 August 2022); https://doi.org/10.1117/12.2628737

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