scholarly journals Effect of Stiffness on Flutter of Composite Wings with High Aspect Ratio

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Shengjun Qiao ◽  
Jin Jiao ◽  
Yingge Ni ◽  
Han Chen ◽  
Xing Liu
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Bending Stiffness ◽  
Torsional Stiffness ◽  
Limit Cycle Oscillation ◽  
Spanwise Direction ◽  
Aerodynamic Loads ◽  
Thin Walled Structures ◽  
Computational Fluid Dynamics Cfd ◽  
Cycle Oscillation

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.

Limit-Cycle Oscillation of High-Aspect-Ratio Wings

2014 ◽  
Vol 556-562 ◽  
pp. 4329-4332
Author(s):  
Yan Ping Xiao ◽  
Yi Ren Yang ◽  
Peng Li
Keyword(s):  
Aspect Ratio ◽  
Limit Cycle ◽  
High Aspect Ratio ◽  
Equations Of Motion ◽  
Beam Theory ◽  
Structural Equations ◽  
Limit Cycle Oscillation ◽  
Nonlinear Beam ◽  
Structural Nonlinearity ◽  
Cycle Oscillation

In this paper structural equations of motion based on nonlinear beam theory and the unsteady aerodynamic forces are gained to study the effects of geometric nonlinearity on the aerodynamic response of high-aspect-ratio wings. Then the Galerkin’s method is used to discretize the equations of motion. The results of HALE wing show good agreement with references. And other results investigate the effects of geometric structural nonlinearity on the response of a wing. Also the complex changes of the limit-cycle oscillation with speed increasing is carefully studied.

scholarly journals A Novel Aerodynamic Force and Flutter of the High-Aspect-Ratio Cantilever Plate in Subsonic Flow

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Li Ma ◽  
Minghui Yao ◽  
Wei Zhang ◽  
Kai Lou ◽  
Dongxing Cao ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Subsonic Flow ◽  
Aerodynamic Force ◽  
Limit Cycle Oscillation ◽  
Cantilever Plate ◽  
Dynamical Equations ◽  
Ansys Fluent ◽  
Cycle Oscillation ◽  
Geometric Relationship

This paper focuses on the derivation of the aerodynamic force for the cantilever plate in subsonic flow. For the first time, a new analytical expression of the quasi-steady aerodynamic force related to the velocity and the deformation for the high-aspect-ratio cantilever plate in subsonic flow is derived by utilizing the subsonic thin airfoil theory and Kutta-Joukowski theory. Results show that aerodynamic force distribution obtained theoretically is consistent with that calculated by ANSYS FLUENT. Based on the first-order shear deformation and von Karman nonlinear geometric relationship, nonlinear partial differential dynamical equations of the high-aspect-ratio plate subjected to the aerodynamic force are established by using Hamilton’s principle. Galerkin approach is applied to discretize the governing equations to ordinary differential equations. Numerical simulation is utilized to investigate the relation between the critical flutter velocity and some parameters of the system. Results show that when the inflow velocity reaches the critical value, limit cycle oscillation occurs. The aspect ratio, the thickness, and the air damping have significant impact on the critical flutter velocity of the thin plate.

Effects of Aeroelastic Nonlinearity on Flutter and Limit Cycle Oscillations of High-Aspect-Ratio Wings

2011 ◽  
Vol 110-116 ◽  
pp. 4297-4306 ◽  
Author(s):  
Keivan Eskandary ◽  
Morteza Dardel ◽  
Mohammad Hadi Pashaei ◽  
Abdol Majid Kani
Keyword(s):  
Aspect Ratio ◽  
Limit Cycle ◽  
High Aspect Ratio ◽  
Large Deflection ◽  
Limit Cycle Oscillation ◽  
Low Velocity ◽  
Wing Model ◽  
Structural Nonlinearities ◽  
Cycle Oscillation ◽  
Compressibility Effects

In this study aeroelastic characteristics of long high aspect ratio wing models with structural nonlinearities in quasi-steady aerodynamics flows are investigated. The studied wing model is a cantilever wing with double bending and torsional vibrations and with large deflection ability in according to Dowell-Hodges wing model. This wing model is valid for long, straight and thin homogeneous isotropic beams. Aerodynamics model is based on quasi-steady aerodynamic which is valid for aerodynamic flows in low velocity and without wake, viscosity and compressibility effects. The effect of different parameters such as mass ratios and stiffness ratios on flutter and divergence velocities and limit cycle oscillation amplitudes are carefully studied.

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

2016 ◽  
Vol 231 (10) ◽  
pp. 1824-1850 ◽  
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.

scholarly journals Modeling and analysis of high aspect ratio wing considering random structural parameters

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bangsheng Fu ◽  
Ya Yang ◽  
Hui Qi ◽  
Jiangtao Xu ◽  
Shaobo Wang
Keyword(s):  
Elastic Modulus ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Structural Parameters ◽  
Torsional Stiffness ◽  
Statistical Characteristics ◽  
Modeling And Analysis ◽  
One Dimensional ◽  
Advanced Composite Materials ◽  
Aeroelastic Model

AbstractWith the application of advanced composite materials in High-Aspect-Ratio wings (HARW), the randomness of structural parameters, such as elastic modulus and Poisson's ratio, is enhanced. Hence, in order to explore the whole picture of aeroelastic problems, it is of great significance to study the role of random structural parameters in aeroelastic problems. In this paper, the dynamic response of flexible HARW considering random structural parameters is analyzed. An aeroelastic model of a one-dimensional cantilevered Euler–Bernoulli beam considering aerodynamic forces acting on the wing is established based on Hamilton's principle. Adopted the idea of simplifying calculation, the effect of random structural parameters is analyzed. Then, considering the elastic modulus and torsional stiffness as continuously one-dimensional random field functions, and discretized by local method. The first and second order recursive stochastic nonlinear finite element equations of wing are derived by using perturbation method. Based on it, statistical expression of aeroelastic effects of the wing is derived. Monte Carlo method is adopted to verify the effectiveness of the method. Numerical simulations indicate that the method proposed can well mirror the statistical characteristics of aeroelastic response.

On the deflexion of an anisotropic cantilever plate with variable rigidity

1979 ◽  
Vol 366 (1727) ◽  
pp. 491-515 ◽  
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Normal Load ◽  
Spanwise Direction ◽  
Cantilever Plate ◽  
Variable Rigidity ◽  
Engineering Theory

An analysis is made of the deflexion of an anisotropic cantilever plate of rectangular planform. The rigidity of the plate varies arbitrarily in the chordwise direction but the spanwise variation, if any, is restricted to certain simple forms. The plate is subjected to a moment, torque and shear applied at the free end and a distributed normal load whose magnitude varies arbitrarily in the chordwise direction but is constant in the spanwise direction. No attention is paid to the root fixity conditions so that the analysis is applicable only to cantilever plates of high aspect ratio. Within this framework, the solutions are exact and they form the basis of a simplified engineering theory in which a newly defined flexural axis plays a prominent role.

scholarly journals Detailed Parametric Investigation and Optimization of a Composite Wing with High Aspect Ratio

2019 ◽  
Vol 2019 ◽  
pp. 1-27 ◽  
Author(s):  
Yu-shan Meng ◽  
Li Yan ◽  
Wei Huang ◽  
Tian-tian Zhang
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Bending Moment ◽  
Element Model ◽  
Torsional Stiffness ◽  
Final Thickness ◽  
Maximum Deformation ◽  
Component Size ◽  
Deformation Problem ◽  
Large Deformation Problem

The large deformation problem of the wing with high aspect ratio cannot be avoided due to the large bending moment and poor torsional stiffness. The wing design follows the following procedure; firstly, the design indexes of high aspect ratio wing are preliminarily formulated referring to some parameters of the Predator UAV. Then, the aerodynamic analysis of the wing is performed, and the stress cloud diagram is obtained. Next, the finite element model of the wing is designed, and the static analysis is conducted in the ANSYS ACP module, and the unreasonable component size is changed. An appropriate thickness which is 12 mm is selected as the final thickness of the wing. Then, the analysis of laying methods of skin structure is conducted. Finally, the composite structure is proved to reduce the maximum deformation and maximum stress effectively compared with the metal wing.

scholarly journals High Aspect Ratio Thin-Walled Structures in D2 Steel through Wire Electric Discharge Machining (EDM)

Micromachines ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 1
Author(s):  
Naveed Ahmed ◽  
Muhammad Ahmad Naeem ◽  
Ateekh Ur Rehman ◽  
Madiha Rafaqat ◽  
Usama Umer ◽  
...  
Keyword(s):  
Aspect Ratio ◽  
Structure Formation ◽  
High Aspect Ratio ◽  
Electrical Discharge Machining ◽  
Machining Processes ◽  
Thin Structures ◽  
Thin Sections ◽  
Thin Walled Structures ◽  
Machining Errors ◽  
D2 Steel

Thin structures are often required for several engineering applications. Although thick sections are relatively easy to produce, the cutting of thin sections poses greater challenges, particularly in the case of thermal machining processes. The level of difficulty is increased if the thin sections are of larger lengths and heights. In this study, high-aspect-ratio thin structures of micrometer thickness (117–500 µm) were fabricated from D2 steel through wire electrical discharge machining. Machining conditions were kept constant, whereas the structure (fins) sizes were varied in terms of fin thickness (FT), fin height (FH), and fin length (FL). The effects of variation in FT, FH, and FL were assessed over the machining errors (FT and FL errors) and structure formation and its quality. Experiments were conducted in a phased manner (four phases) to determine the minimum possible FT and maximum possible FL that could be achieved without compromising the shape of the structure (straight and uniform cross-section). Thin structures of smaller lengths (1–2 mm long) can be fabricated easily, but, as the length exceeds 2 mm, the structure formation loses its shape integrity and the structure becomes broken, deflected, or deflected and merged at the apex point of the fins.

scholarly journals Automated Drilling of High Aspect Ratio, Small Diameter Holes in Remote, Confined Spaces

2020 ◽  
Author(s):  
Michal Rittikaidachar ◽  
Clint Hobart ◽  
Jonathon E. Slightam ◽  
Jiann-Cherng Su ◽  
Stephen P. Buerger
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Oil And Gas ◽  
Small Diameter ◽  
Torsional Stiffness ◽  
Hole Drilling ◽  
Aspect Ratios ◽  
Drill Bits ◽  
Conventional Methods

Abstract We describe the development and benchtop prototype performance characterization of a mechatronic system for automatically drilling small diameter holes of arbitrary depth, to enable monitoring the integrity of oil and gas wells in situ. The precise drilling of very small diameter, high aspect ratio holes, particularly in dimensionally constrained spaces, presents several challenges including bit buckling, limited torsional stiffness, chip clearing, and limited space for the bit and mechanism. We describe a compact mechanism that overcomes these issues by minimizing the unsupported drill bit length throughout the process, enabling the bit to be progressively fed from a chuck as depth increases. When used with flexible drill bits, holes of arbitrary depth and aspect ratio may be drilled orthogonal to the wellbore. The mechanism and a conventional drilling system are tested in deep hole drilling operation. The experimental results show that the system operates as intended and achieves holes with substantially greater aspect ratios than conventional methods with very long drill bits. The mechanism enabled successful drilling of a 1/16″ diameter hole to a depth of 9″, a ratio of 144:1. Dysfunctions prevented drilling of the same hole using conventional methods.

Sign in / Sign up

Export Citation Format

Share Document