The Use of a Simplified Structural Model as an Aid in the Strain Gage Calibration of a Complex Wing

Jenkins, Jerald M. and Kuhl, Albert E. and Carter, Alan L. (1977) The Use of a Simplified Structural Model as an Aid in the Strain Gage Calibration of a Complex Wing. Technical Report NASA TM 56046, Research Engineering, NASA Dryden Flight Research Center.

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Abstract

Modern, complex structural arrangements have complicated the task of measuring flight loads with calibrated strain gages. This paper examines the use of a relatively simple structural model to characterize the load responses of strain gages located on various spars of a delta wing. Strains measured during a laboratory load calibration of a wing structure are compared with calculations obtained from a simplified NASA structural analysis (NASTRAN) model. Calculated and measured influence coefficient plots that show the shear, bending, and torsion characteristics of typical strain gage bridges are presented. Typical influence coefficient plots are shown for several load equations to illustrate the derivation of the equations from the component strain gage bridges. A relatively simple structural model was found to be effective in predicting the general nature of strain distributions and influence coefficient plots. The analytical processes are shown to be an aid in obtaining a good load calibration. The analytical processes cannot, however, be used in lieu of an actual load calibration of an aircraft wing.

EPrint Type:	NASA Technical Memorandum
Keywords:	Load calibration, Strain gages, Flight loads
Subjects:	Aircraft/Project: Nonaircraft-specific (31 - 39) Engineering: (39) Structural Mechanics
ID Code:	695
Deposited On:	14 Febuary 2006
Additional Information:	19 pages.