Aerospace Science and Technology
Sayed Hossein Moravej Barzani; Mahdi Mortazavi; Hossein Shahverdi
Abstract
In this paper, the effects caused by the combination of folding angles simultaneously with changing the stiffness ratio of different parts of a folding wing are investigated. The geometrically exact fully intrinsic equations are employed to simulated the wing nonlinear dynamic behavior. The important ...
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In this paper, the effects caused by the combination of folding angles simultaneously with changing the stiffness ratio of different parts of a folding wing are investigated. The geometrically exact fully intrinsic equations are employed to simulated the wing nonlinear dynamic behavior. The important advantages of these geometrically exact equations can be seen as complete modeling without simplifying assumptions in large deformations, low-order nonlinearities, and thus less complexity. In this research, folding angles have been used in the geometrically exact fully intrinsic beam equations and the combination of different folding angles is studied. The applied aerodynamic loads in an incompressible flow regime are determined employing Peter’s unsteady aerodynamic model. In order to check the stability of the system, first the resulting non-linear partial differential equations are discretized, and then linearized about the nonlinear steady-state condition. By obtaining the eigenvalues of the linearized system, the stability of the wing is evaluated. Furthermore, investigation of the effects of the stiffness on the flutter speed and frequency of the folding wing for various folding angles, is another achievement of this study. It is observed that the combination of folding angles can significantly delay the flutter speed and improve the performance of the bird.
Hossein H. Shahverdi; A.S Nobari; H Bahrami Torabi
Volume 11, Issue 1 , June 2017
Abstract
The aim of this paper is to provide an aeroelastic computational tool which determines the induced wing loads during flapping flight. For this purpose, a Finite Element (FE) code based on a four-node plate bending element formulation is developed to simulate the aeroelastic behavior of flapping wings ...
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The aim of this paper is to provide an aeroelastic computational tool which determines the induced wing loads during flapping flight. For this purpose, a Finite Element (FE) code based on a four-node plate bending element formulation is developed to simulate the aeroelastic behavior of flapping wings in low incompressible flow. A quasi-steady aerodynamic model is incorporated into the aeroelastic model for predicting the aerodynamic loads. In order for the validation of the present tool, the modal and dynamic response analyses of a rotating flat plate under pure flapping motion are firstly examined and the effect of dynamic stiffness on the plate response, due to the presence of shortening terms in the equations of motion, is also investigated. Finally, the aeroelastic analysis of an insect-like wing under a specified motion is carried out and the induced loads including shear force and bending moment at the wing root are determined. The obtained results signify the contribution of wing structural elasticity to the induced loads.