Investigation of the flutter of a composite wing
Tactical Missile Corporation, 7, Lenin str., Korolev, Moscow region, 105005, Russia
A method of finding the mechanical characteristics of a composite wing is considered. A preliminary computation of the flutter safety is carried out for several variants of layered composite structures. A Ritz method combined with the Ritz polynomial approximation is used for the computation of the flutter stability in subsonic flows. Two variants of the layered structure are considered and the flutter-safe variant is selected.
The mechanical properties are found for each of layers of laminated composite, and then the properties of the layered structure are computed taking into account the winding angles for the fiber reinforcement on the groundwork of the common coordinate frame. Using the found properties the flutter stability of the considered composite wing is estimated by Ritz method.
The flutter-safest variant of the wing structure is found out. The efficiency of the proposed method is based on the simplicity of the mathematical model, the quickness of data preprocessing as well as the computation speed. The preliminary computing realized for various composite structures allows one to benefit financially by identifying the possible weaknesses of structures without expensive real testing.
The proposed calculation method can be used for linearly elastic and perfectly bounded layered structures represented in thin plates, particularly wings, rudders and other bearing surfaces of the aircraft. Ritz polynomial method can be applied to estimate flutter safety of separate parts of the aircrafts as well as of all aircrafts in general. For the well-posed problems with accurate input data the calculation error is up to 1-5%.
The proposed method has been implemented as the «Flutter Analysis Program» software developed by author using the «Wolfram Mathematica 8» package. This software combines the high-precision computations and the simplicity of the input data. Another important feature of the software is the possibility of the calculations not only for composite materials, but also for orthotropic and isotropic ones. The main restrictions are the linear elasticity of the materials, the requirement of the perfect bounding of the layered structure of thin plates and applicability of the Kirchhoff hypothesis.
Keywords:flutter, Ritz polynomial calculation, composite, modeling of the aircraft
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