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Proceedings Paper

Theoretical limits of dimensional stability for space structures
Author(s): Benjamin P. Dolgin; Jovan Moacanin; Timothy P. O'Donnell
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Paper Abstract

Future NASA missions such as the Great Observatories of the 21st Century require structures which can be maintained with micron to nanometer accuracy. This dimensional stability (OS) must be maintained over the 5 to 10 years of mission lifetime. A high DS, which in this case means the system's ability to retain geometrical properties related to the system's performance, will most likely be achieved by a combination of dimensionally stable materials and active controls. Actively controlled structures can achieve a very high degree of DS. However, the inherent instability of the building blocks limits the ultimate DS which can be realized. This article discusses basic limitations on the DS which can be achieved by an actively controlled system which uses passive materials with limited stability. Thermodynamics limits the ultimately attainable DS. For example, the amplitude of the longitudinal vibration in a space truss structure is related to the temperature of the structure. The amplitude of this axial vibration grows with increasing temperature. Another instability mechanism is the temperature gradients through so called "zero coefficient of thermal expansion (CTE)" materials. "Zero CTE" materials will, under some conditions, show no change in at least one dimension when the material is heated. We will show, that in non-equilibrium conditions "zero CTE" materials can behave as if they had a CTE nearly equal to double the CTE of their stiffest phase. These and other mechanisms influence the space system's performance below 0.1 part per million dimensional stability.

Paper Details

Date Published: 1 December 1991
PDF: 11 pages
Proc. SPIE 1533, Optomechanics and Dimensional Stability, (1 December 1991); doi: 10.1117/12.48859
Show Author Affiliations
Benjamin P. Dolgin, Jet Propulsion Lab. (United States)
Jovan Moacanin, Jet Propulsion Lab. (United States)
Timothy P. O'Donnell, Jet Propulsion Lab. (United States)

Published in SPIE Proceedings Vol. 1533:
Optomechanics and Dimensional Stability
Roger A. Paquin; Daniel Vukobratovich, Editor(s)

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