Displacement Theories for In-Flight Deformed Shape Predictions of Aerospace Structures
Ko, William L. and Richards, W.L. and Tran, Van T. (2007) Displacement Theories for In-Flight Deformed Shape Predictions of Aerospace Structures. Technical Report NASA/TP-2007-214612, Research and Engineering, NASA Dryden Flight Research Center.
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Abstract
Displacement theories are developed for a variety of structures with the goal of providing real-time shape predictions for aerospace vehicles during flight. These theories are initially developed for a cantilever beam to predict the deformed shapes of the Helios flying wing. The main structural configuration of the Helios wing is a cantilever wing tubular spar subjected to bending, torsion, and combined bending and torsion loading. The displacement equations that are formulated are expressed in terms of strains measured at multiple sensing stations equally spaced on the surface of the wing spar. The bending and torsion strain data are to be input to the displacement equations for calculations of slopes, deflections, and cross-sectional twist angles of the wing spar at the strain-sensing stations. Displacement theories for other structures, such as tapered cantilever beams, two-point supported beams, wing boxes, and plates also are developed. The accuracy of the displacement theories is successfully validated by finite-element analysis and classical beam theory using input-strains generated by finite-element analysis. The displacement equations and associated strain-sensing system (such as fiber optic sensors) create a powerful means for in-flight deformation monitoring of aerospace structures. Because local strains are used as inputs for the structural deformation predictions described in this report, this method serves multiple purposes for structural shape sensing, loads monitoring, and structural health monitoring. Ultimately, the calculated displacement data can be visually displayed to the ground-based pilot or used as input to the control system to actively control the shape of structures during flight. The displacement theories could also be easily applied to calculate the deformed shapes of a variety of high-aspect-ratio flexible structures, aircraft wing rotorcraft vehicles, space vehicles, wind turbine blades (for the alternative energy community), space-based structures (such as booms and antennae), and long-span civil structures (such as bridges and dams).
| EPrint Type: | NASA Technical Publication |
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| Keywords: | Deflection equations, Displacement theories, Embedded strain sensing, In-flight shape predictions, Slope equations |
| Subjects: | (31 - 39) Engineering: (39) Structural Mechanics |
| ID Code: | 1774 |
| Deposited On: | 02 November 2007 |
| Additional Information: | 82 pages. Ko, Richards, and Tran, NASA Dryden Flight Research Center. The invention described in this report is the subject of a currently pending patent application: Real-Time Structural Shape Sensing Techniques using Surface Strain Sensor Measurements (Inventors: William Leslie Ko and W. Lance Richards) before the U.S. Patent and Trademark Office. |
