Frequency Interval Optimization of a Wing Considering Uncertain Locations of Lumped Masses
Publication: Journal of Aerospace Engineering
Volume 30, Issue 5
Abstract
The locations of lumped masses, e.g., engines, missiles, fuel tanks, etc., can alter the dynamic characteristics of the airframes, thereby affect the critical flutter speed and gust response of the wing. Usually the practical location of the lumped mass is uncertain due to errors in processing and manufacturing; therefore, frequency interval optimization of the wing under uncertain locations of lumped masses is developed in this paper. The uncertain locations of the lumped masses are described by interval variables; the optimization problem with interval variables can be transformed into an equivalent deterministic problem by the first-order Taylor series of the objective and constraint function, and then the optimal locations of the lumped masses can be obtained by the sequential quadratic programming algorithm. A straight wing modeled by beam elements, with uncertain locations of lumped masses, was studied to demonstrate this method, and the results show that the bounds of the optimal results can be narrowed by improving the accuracy of the locations of the lumped masses. The example of a swept wing is given in this paper to illustrate that the frequency interval optimization procedure can be done by integrating commercial software so this method can easily be applied to solve the complex problem in practice. The results show that interval optimization can give the bounds of these optimal frequencies, and increase the frequency difference between the second bending mode and the first torsion mode, which can increase critical flutter speed.
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Acknowledgments
This work was supported by the Fundamental Research Fund of Northwestern Polytechnical University and the Aerospace Technology Support Foundation, China (2014-Ht-XGD).
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Published In
Journal of Aerospace Engineering
Volume 30 • Issue 5 • September 2017
Copyright
©2017 American Society of Civil Engineers.
History
Received: Dec 9, 2015
Accepted: Jan 6, 2017
Published online: Mar 31, 2017
Discussion open until: Aug 31, 2017
Published in print: Sep 1, 2017
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