Evaluation of a Strain-Gage Load Calibration on a Low-Aspect-Ratio Wing Structure at Elevated Temperature

Reardon, Lawrence F. (1989) Evaluation of a Strain-Gage Load Calibration on a Low-Aspect-Ratio Wing Structure at Elevated Temperature. Technical Report NASA TP-2921, Research Engineering, NASA Dryden Flight Research Center.

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Abstract

This report addresses the environmental aspect of elevated temperature and how it relates to the science of strain gage calibrations of aircraft structures. A section of a wing designed for a high-speed aircraft structure was used to study this problem. This structure was instrumented with strain gages calibrated at both elevated and room temperatures. Load equations derived from a high-temperature load calibration were compared with equations derived from an identical load calibration at room temperature. The implications of the high temperature load calibration were studied from the viewpoint of applicability and necessity. Load equations derived from the room temperature load calibration resulted in generally lower equation standard errors than equations derived from the elevated temperature load calibration. A distributed load was applied to the structure at elevated temperature and strain gage outputs were measured. This applied load was then calculated using equations derived from both the room temperature and elevated temperature calibration data. It was found that no significant differences between the two equation systems existed in terms of computing this applied distributed load, as long as the thermal shifts resulting from thermal stresses could be identified. This identification requires a heating of the structure. Therefore, it is concluded that for this structure, a high temperature load calibration is not required, however, a heating of the structure is required to determine thermal shifts.

EPrint Type:	NASA Technical Publication
Keywords:	Calibration, Elevated temperature, Hypersonic wing test structure, Strain gage
Subjects:	(31 - 39) Engineering: (39) Structural Mechanics
ID Code:	390
Deposited On:	16 Febuary 2005
Additional Information:	39 pages.