Frequency Interval Optimization of a Wing Considering Uncertain Locations of Lumped Masses

• Published in: Journal of aerospace engineering 2017-09, Vol.30 (5)
• Main Authors: Li, Yi, Wang, Dong, Wang, Tianhong
• Format: Article
• Language: English
• Subjects: Algorithms; Flutter; Intervals; Mathematical models; Optimization; Swept wings; Technical Papers; Vibration; Wings (aircraft)
• ISSN: 0893-1321; 1943-5525
• DOI: 10.1061/(ASCE)AS.1943-5525.0000732

AbstractThe 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.