The Effects of Nonlinear Bending Stiffness on the Flutter Speed and Pitch Motion of UAV with High Aspect Ratio

High aspect ratio wing (HARW) structures will deform greatly under aerodynamic loads, and changes in the stiffness will have a great impact on the flutter characteristics of such wings. Based on this, this paper presents an effective method to determine the effect of the stiffness on the flutter characteristics of HARWs. Based on the calculation theory of the mechanical profile of thin-walled structures, the torsional stiffness and bending stiffness of the wing are obtained through calculation. We use the fluid-structure coupling method to analyze the flutter characteristics of the wing, and we use our research results based on the corotational (CR) method to perform structural calculations. The load is calculated using a computational fluid dynamics (CFD) solver. The results show that, compared with the original wing, when the bending stiffness and torsional stiffness of the wing along the spanwise direction increase by 8.28% and 5.22%, respectively, the amplitude of the flutter decreases by approximately 30%. Increasing the stiffness in the range of 0.4 to 0.6 Mach has a greater impact on the flutter critical velocity, which increases by 12.03%. The greater the aircraft’s flight speed is, the more severe the stiffness affects the wing limit cycle oscillation (LCO) amplitude.

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The effect of stiffness and geometric parameters on the nonlinear aeroelastic performance of high aspect ratio wings

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410016675893 ◽

2016 ◽

Vol 231 (10) ◽

pp. 1824-1850 ◽

Cited By ~ 3

Author(s):

F Afonso ◽

G Leal ◽

J Vale ◽

É Oliveira ◽

F Lau ◽

...

Keyword(s):

Aspect Ratio ◽

High Aspect Ratio ◽

Nonlinear Behavior ◽

Geometric Parameters ◽

Torsional Stiffness ◽

Design Parameters ◽

Sweep Angle ◽

Flutter Speed ◽

Wing Model ◽

Aspect Ratios

The increase in wing aspect ratio is gaining interest among aircraft designers in conventional and joined-wing configurations due to the higher lift-to-drag ratios and longer ranges. However, current transport aircraft have relatively small aspect ratios due their increased structural stiffness. The more flexible the wing is more prone to higher deflections under the same operating condition, which may result in a geometrical nonlinear behavior. This nonlinear effect can lead to the occurrence of aeroelastic instabilities such as flutter sooner than in an equivalent stiffer wing. In this work, the effect of important stiffness (inertia ratio and torsional stiffness) and geometric (sweep and dihedral angles) design parameters on aeroelastic performance of a rectangular high aspect ratio wing model is assessed. The torsional stiffness was observed to present a higher influence on the flutter speed than the inertia ratio. Here, the decrease of the inertia ratio and the increase of the torsional stiffness results in higher flutter and divergence speeds. With respect to the geometric parameters, it was observed that neither the sweep angle nor the dihedral angle variations caused a substantial influence on the flutter speed, which is mainly supported by the resulting smaller variations in torsion and bending stiffness due to the geometric changes.

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The Research on Aeroelasticity of the Vehicle Wing Surface

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.284-286.2456 ◽

2011 ◽

Vol 284-286 ◽

pp. 2456-2460

Author(s):

Zhi Ling Peng

Keyword(s):

Aspect Ratio ◽

High Aspect Ratio ◽

Aerodynamic Force ◽

Wing Surface ◽

Flutter Speed ◽

Straight Wing

By taking high aspect ratio straight wing as the research object, static aerodynamic force and dynamic aerodynamic force are detailed analysed and researched. The flutter speed of panel derived from Unsteady Theory and Theory.

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