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 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.

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.

Boehmite Nanofibers as a Dispersant for Nanotubes in an Aqueous Sol

2018 ◽  
Author(s):  
Gen Hayase
Keyword(s):  
Carbon Nanotubes ◽  
Aspect Ratio ◽  
Aqueous Solutions ◽  
High Aspect Ratio ◽  
Multiwall Carbon Nanotubes ◽  
Multiwall Carbon ◽  
Nanotube Films

By exploiting the dispersibility and rigidity of boehmite nanofibers (BNFs) with a high aspect ratio of 4 nm in diameter and several micrometers in length, multiwall-carbon nanotubes (MWCNTs) were successfully dispersed in aqueous solutions. In these sols, the MWCNTs were dispersed at a ratio of about 5–8% relative to BNFs. Self-standing BNF–nanotube films were also obtained by filtering these dispersions and showing their functionality. These films can be expected to be applied to sensing materials.

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