Analysis of Wing Flexure Deformation Based on ANSYS
Xueyan Zhang, Yan Zhao and Fan Si, Beihang University, China
Due to the aerodynamic loads and turbulence, the wing is elastically deformed during transfer alignment, which causes discrepancies of the output angular velocity of the slave inertial navigation units between the master inertial navigation units. Traditional transfer alignment used to set a wind tunnel experiment, and establish a structure database of the airfoil to measure the deformation of specific points. To reduce the high cost and simplify the process, this paper presents a finite element analysis of wing deformation based on ANSYS. Aimed at solving the stress and strain loaded on the wing, this paper applies ANSYS to simulate multiple stress distribution and calculate the value. Considering material characteristics, wing structure, design principle and external loads, the overall layout and initial design parameters are set. Firstly, this paper establishes a wing model. A large lift coefficient is chosen to achieve a long-endurance and high-altitude flight, which improves the dynamic pressure of the wing. Obviously the airfoils with different Reynolds numbers make a big difference in the aerodynamic performance. Hence, NACA2412 is chosen as the airfoil, because it shows a better performance according to calculation. It is proved that high aspect ratio wings can not only improve the performance, but also increase the air-range. Therefore, a high aspect ratio wing assembly model is established, consist of the ribs, the spars and the skin. Two spars mainly bear the bending moment and the shear force, so the structural steel is used as their material to ensure sufficient rigidity. The wing ribs and the skin are made of aluminum alloy, which reduces the structural weight. Secondly, this paper uses model analysis, which provides data for further studies, especially the harmonic response analysis. Through the model analysis, this paper obtains the natural frequencies and deformation maps of each order under specific constraints. And it have great significance to the design and improvement of the wing in the high-altitude flight. On the basis of the analysis results, the vibration modes of the first five natural frequencies have both bending deformation and torsional deformation. Especially, the dramatic changes of vibration modes in the torsion deformation may lead to serious deterioration of aerodynamic characteristics, even the flutter. Thirdly, based on the aerodynamic performance and fluid-structure coupling calculation, the wing is subjected to dynamic loads. On the wing, different hang points of slave inertial navigations has different deformation. Hence, the output of each inertial navigation includes the angular velocity and the deformation on the specific hang point. Moreover, a transient structural dynamic analysis is set up, to figure out the information of displacement, velocity, acceleration and angular velocity of each hang point. After an establishment of a coordinate system, the curve fitting is performed by least square method, and the time graphs of displacement, velocity, acceleration and angular velocity are obtained. At the same time, the displacement, velocity, acceleration and angular velocity can be obtained from the output of the mater inertial navigation and the slave inertial navigation. Finally, by comparing the ANSYS data with the inertial navigation data, the research result is proved to be accurate, and is feasible to be applied to reduce negative influence of the wing deformation on transfer alignment and improve its precision effectively.
Keywords: wing deformation?inertial navigation, transfer alignment, finite element analysis, ANSYS