Further Development of Ko Displacement Theory for Deformed Shape Predictions of Non-uniform Aerospace Structures

Ko, William L. and Fleischer, Van Tran (2009) Further Development of Ko Displacement Theory for Deformed Shape Predictions of Non-uniform Aerospace Structures. Technical Report NASA TP-2009-214643, Research and Engineering, NASA Dryden Flight Research Center.

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Abstract

The Ko displacement theory previously formulated for deformed shape predictions of nonuniform beam structures is further developed mathematically. The further developed displacement equations are expressed explicitly in terms of geometrical parameters of the beam and bending strains at equally spaced strain-sensing stations along the multiplexed fiber-optic sensor line installed on the bottom surface of the beam. The bending strain data can then be input into the displacement equations for calculations of local slopes, deflections, and cross-sectional twist angles for generating the overall deformed shapes of the nonuniform beam. The further-developed displacement theory can also be applied to the deformed shape predictions of nonuniform two-point supported beams, nonuniform panels, nonuniform aircraft wings and fuselages, and so forth. The high degree of accuracy of the further-developed displacement theory for nonuniform beams is validated by finite-element analysis of various nonuniform beam structures. Such structures include tapered tubular beams, depth-tapered unswept and swept wing boxes, width-tapered wing boxes, and double-tapered wing boxes, all under combined bending and torsional loads. The Ko displacement theory, combined with the fiber-optic strain-sensing system,provide a powerful tool for in-flight deformed shape monitoring of unmanned aerospace vehicles by ground-based pilots to maintain safe flights.

EPrint Type:	NASA Technical Publication
Keywords:	Deflection equations, Displacement theories, Embedded strain sensing, In-flight predictions, Slope equations.
Subjects:	(31 - 39) Engineering: (39) Structural Mechanics
ID Code:	2038
Deposited On:	18 September 2009
Additional Information:	86 pages.