scholarly journals A Parametric Study on the Aeroelasticity of Flared Hinge Folding Wingtips

Aerospace ◽  
2021 ◽  
Vol 8 (8) ◽  
pp. 221
Author(s):  
Rafic M. Ajaj ◽  
Erick I. Saavedra Flores ◽  
Mohammadreza Amoozgar ◽  
Jonathan E. Cooper
Keyword(s):  
Parametric Study ◽  
Nonlinear Behavior ◽  
Aerodynamic Load ◽  
Aeroelastic Response ◽  
Beam Elements ◽  
Aeroelastic Analysis ◽  
Aeroelastic Model ◽  
Strip Theory ◽  
Line Angle ◽  
Tip Mass

This paper presents a parametric study on the aeroelasticity of cantilever wings equipped with Flared Hinge Folding Wingtips (FHFWTs). The finite element method is utilized to develop a computational, low-fidelity aeroelastic model. The wing structure is modelled using Euler–Bernoulli beam elements, and unsteady Theodorsen’s aerodynamic strip Theory is used for aerodynamic load predictions. The PK method is used to estimate the aeroelastic boundaries. The model is validated using three rectangular, cantilever wings whose properties are available in literature. Then, a rectangular, cantilever wing is used to study the effect of folding wingtips on the aeroelastic response and stability boundaries. Two scenarios are considered for the aeroelastic analysis. In the first scenario, the baseline, rectangular wing is split into inboard and outboard segments connected by a flared hinge that allows the outboard segment to fold. In the second scenario, a folding wingtip is added to the baseline wing. For both scenarios, the influence of fold angle, hinge-line angle (flare angle), hinge stiffness, tip mass and geometry are assessed. In addition, the load alleviation capability of FHFWT is evaluated when the wing encounters discrete (1-cosine) gusts. Finally, the hinge is assumed to exhibit cubic nonlinear behavior in torsion, and the effect of nonlinearity on the aeroelastic response is assessed and analyzed for three different cases.

Investigation of Computational Non-Linear Aeroelastic Response of High Aspect Ratio Wing

2013 ◽  
Vol 419 ◽  
pp. 55-61
Author(s):  
Hammad Rahman ◽  
Min Li
Keyword(s):  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Parametric Design ◽  
Aerodynamic Load ◽  
Linear Deformation ◽  
Aeroelastic Response ◽  
Simplified Approach ◽  
Strip Theory ◽  
Non Linear ◽  
The Impact

Aircrafts with high aspect ratio wings are most eligible candidates for high altitude and long endurance flights. Such wings show a non-linear deformation behavior because of structural geometric non-linearity. In the present study both linear and non-linear static aeroelastic behaviors of a high aspect ratio rectangular flat plate wing are analyzed using a simplified approach. The main emphasis lies in the tremendous change of lift distribution on the flexible high aspect ratio wing when large deflections are incorporated in the static aeroelastic analysis. The computational static aeroelastic simulations are performed in the finite element method based commercial software ANSYS-14. The aerodynamic load is calculated using the strip theory. Since the aero-load changes with the twisting deformation hence a user defined script is written using ANSYS parametric design language (APDL). The computationally achieved divergence velocity results are compared with the analytical results. The results of parametric study at different flight load conditions and angles of attack have highlighted the role of geometric nonlinearities in both bending and twisting deformations. The impact of follower pressure forces on the aeroelastic response is also investigated.

Effect of Segmented Electrodes on Piezo-Elastic and Piezo-Aero-Elastic Responses of Generator Plates

2009 ◽  
Author(s):  
Carlos De Marqui ◽  
Alper Erturk ◽  
Daniel J. Inman
Keyword(s):  
Electrical Power ◽  
Elastic Behavior ◽  
Elastic Model ◽  
Fe Model ◽  
Aeroelastic Response ◽  
Aerodynamic Model ◽  
Frequency Excitation ◽  
Elastic Responses ◽  
Electrical Power Output ◽  
Tip Mass

In this paper, the use of segmented electrodes is investigated to avoid cancellation of the electrical outputs of the torsional modes in energy harvesting from piezo-elastic and piezo-aero-elastic systems. The piezo-elastic behavior of a cantilevered plate with an asymmetric tip mass under base excitation is investigated using an electromechanically coupled finite element (FE) model. Electromechanical frequency response functions (FRFs) are obtained using the coupled FE model both for the continuous and segmented electrodes configurations. When segmented electrodes are considered torsional modes also become significant in the resulting electrical FRFs, improving broadband (or varying-frequency excitation) performance of the generator plate. The FE model is also combined with an unsteady aerodynamic model to obtain the piezo-aero-elastic model. The use of segmented electrodes to improve the electrical power generation from aeroelastic vibrations of plate-like wings is investigated. Although the main goal here is to obtain the maximum electrical power output for each airflow speed (both for the continuous and segmented electrode cases), piezoelectric shunt damping effect on the aeroelastic response of the generator wing is also investigated.

Modified Harmonic Balance Method for Nonlinear Aeroelastic Analysis of Two Degree-of-Freedom Airfoils in Supersonic Flow

2018 ◽  
Vol 18 (06) ◽  
pp. 1871006 ◽  
Author(s):  
Yaobin Niu ◽  
Zhongwei Wang
Keyword(s):  
Harmonic Balance ◽  
Harmonic Balance Method ◽  
Current Method ◽  
Degree Of Freedom ◽  
Balance Method ◽  
Aerodynamic Load ◽  
Nonlinear Aeroelasticity ◽  
Unsteady Aerodynamic ◽  
Aeroelastic Analysis ◽  
Two Degree Of Freedom

In this paper, a new modified harmonic balance method is presented for the nonlinear aeroelastic analysis of two degree-of-freedom airfoils. Using this method, the nonlinear problem is first translated into a minimization problem, and the Particle Swarm Optimization which has high calculation efficiency is adopted to solve the problem. The proposed method is used to solve the nonlinear aeroelastic behavior of supersonic airfoil, with the unsteady aerodynamic load evaluated by the piston theory. Three examples of nonlinear aeroelasticity with significantly different coefficients are prepared, in which the frequencies and amplitudes of the limit cycles are obtained. The results show that the present current method is computationally more efficient.

The effects of structural and aerodynamic nonlinearities on the energy harvesting from airfoil stall-induced oscillations

2019 ◽  
Vol 25 (14) ◽  
pp. 1991-2007 ◽  
Author(s):  
Carlos R. dos Santos ◽  
Flávio D. Marques ◽  
Muhammad R. Hajj
Keyword(s):  
Energy Harvesting ◽  
Degrees Of Freedom ◽  
Electrical Power ◽  
Piezoelectric Element ◽  
Free Play ◽  
Aeroelastic Response ◽  
Wind Speeds ◽  
Aeroelastic Model ◽  
Structural Nonlinearities ◽  
Semi Empirical

An airfoil may undergo stall-induced oscillations beyond the critical flutter speed with amplitudes determined by aerodynamic nonlinearities due to the dynamic stall. Stall-induced oscillations yield intense periodical motions that can be used to convert the airflow energy into electrical power. The inclusion of structural nonlinearities contributes to the complexity of the aeroelastic response. In this sense, the present work models and analyzes for the first time the effects of structural and aerodynamic nonlinearities in the potential of extracting energy from pitching and plunging motions of an airfoil during stall-induced oscillations. A computational model is employed, based on the electro-aeroelastic differential equations modeling a typical aeroelastic section with two degrees of freedom with an electrical generator connected to the pitching motion and a piezoelectric element connected to the plunging motion. The Beddoes–Leishman semi-empirical model is used to represent the unsteady aerodynamic loading. Concentrated structural nonlinearities, such as the hardening effect and free-play, are also considered. Bifurcation diagrams and harvested power calculations are used to analyze the performance of each energy harvesting scheme. The results show that nonlinear pitching stiffness reduces the average harvested power from this degree of freedom in a range of wind speeds. However, the presence of a free-play spring reduces the flutter velocity and initiates the harvesting at lower wind speeds. In conclusion, the present electro-aeroelastic model can be used to find optimal parameters of a harvester from airfoil stall-induced oscillations for a specific application.

Nonlinear dynamic analysis of a Stockbridge damper

2019 ◽  
Vol 46 (9) ◽  
pp. 828-835
Author(s):  
Nilson Barbieri ◽  
Marlon Elias Marchi ◽  
Marcos José Mannala ◽  
Renato Barbieri ◽  
Lucas de Sant’Anna Vitor Barbieri ◽  
...  
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Nonlinear Dynamic Analysis ◽  
Nonlinear Behavior ◽  
Vibration Data ◽  
Electric Transmission Line ◽  
Good Concordance ◽  
Tip Mass ◽  
The Mathematical Model ◽  
Stockbridge Damper

The purpose of this work is to validate a nonlinear mathematical model (finite element method) for dynamic simulation of Stockbridge dampers of electric transmission line cables. To obtain the mathematical model, a nonlinear cantilever beam with a tip mass was used. The mathematical model incorporates a nonlinear stiffness matrix of the element due to the nonlinear curvature effect of the beam. To validate the mathematical model, the numerical results were compared with experimental data obtained on a machine adapted from cam test. Five different circular cam profiles with eccentricities of 0.25, 0.5, 0.75, 1.25, and 1.5 mm were used. Vibration data were collected through three accelerometers arranged along the sample. A good concordance was found between the numerical and experimental data. The same behavior was observed in tests of another Stockbridge damper excited by a shaker. The nonlinear behavior of the system was evidenced.

Parametric Study of Operability for a Tourist Submarine

2004 ◽  
Author(s):  
R. T. Paein Koulaei ◽  
M. Rad ◽  
S. M. Mousaviraad ◽  
S. H. Sadathosseini
Keyword(s):  
Parametric Study ◽  
Point Of View ◽  
Hydrodynamic Problem ◽  
Sea State ◽  
Strip Theory ◽  
Speed Effect ◽  
Duration Of Operation

These days, tourist submarine industry has become of increasing interest and prosperity. A tourist submarine operating beneath a seaway suffers different undesired motions which may cause difficulty in operability for the vehicle and habitability of its passengers. From this point of view, this paper studies the hydrodynamic problem of submarine operability in waves. In this investigation strip theory has been used and effects of different parameters of sea state, sea direction, depth, speed and duration of operation have been considered. Results of presented case study indicate that speed effect is insignificant while the operating depth role seems more important.

Effects of Tip Mass and Interaction Force on Nonlinear Behavior of Force Modulation FM-AFM Cantilever

2016 ◽  
Vol 33 (2) ◽  
pp. 257-268 ◽  
Author(s):  
K. E. Torkanpouri ◽  
H. Zohoor ◽  
M. H. Korayem
Keyword(s):  
Frequency Shift ◽  
Nonlinear Model ◽  
Equations Of Motion ◽  
Nonlinear Behavior ◽  
Interaction Force ◽  
Beam Model ◽  
Frequency Shifts ◽  
Excitation Mode ◽  
Force Modulation ◽  
Tip Mass

AbstractInfluences of the tip mass, excitation mode of Frequency Modulated Atomic Force Microscope (FM-AFM) on the resonance frequency shift in force modulation (FM) mode are studied. Governing equations of motion are determined based on Timoshenko beam model with concentrated end mass. Approach point and base amplitude are set such that the FM-AFM remains just in FM mode. Either the linearized and nonlinear Derjaguin-Muller-Toporov (DMT) model are investigated. Then frequency shifts are determined for various interaction force regimes. It is showed the effect of tip mass on frequency shift is significant even for small tips. Nonlinear model shows lower frequency shifts in comparison with linearized model. It is showed that the amplitude of response is increased by increasing the tip mass and order of base excitation. Deviation of frequency shift between linearized and nonlinear solution are studied. It is declared that the error between linearized and nonlinear model is complicated. A deviation index is used for explaining behavior of error while tip mass and excitation mode are changed. It is showed, this index predicts the trend of error in all excitation modes and force cases. Behavior of system is linearizing by increasing the order of excitation, generally.

Parametric study of the aeroelastic response of mistuned bladed disks

2007 ◽  
Vol 85 (11-14) ◽  
pp. 852-865 ◽  
Author(s):  
Zhijiang He ◽  
Bogdan I. Epureanu ◽  
Christophe Pierre
Keyword(s):  
Parametric Study ◽  
Bladed Disks ◽  
Aeroelastic Response

Generic Modeling and Parametric Study of Flapping Wing Micro-Air-Vehicle

2012 ◽  
Vol 225 ◽  
pp. 18-25 ◽  
Author(s):  
Harijono Djojodihardjo ◽  
Alif Syamim Syazwan Ramli ◽  
Surjatin Wiriadidjaja
Keyword(s):  
Parametric Study ◽  
Three Dimensional ◽  
Unsteady Aerodynamics ◽  
Flapping Wing ◽  
Phase Lag ◽  
Aerodynamic Model ◽  
Strip Theory ◽  
Thrust Characteristics ◽  
Generic Modeling ◽  
Wing Geometry

The present work is focused on the unsteady aerodynamics of bio-inspired flapping wing to produce lift and thrust for hovering and forward flight. A generic approach is followed to understand and mimic the mechanism and kinematics of ornithopter by considering the motion of a three-dimensional rigid thin wing in flapping and pitching motion, using strip theory and two-dimensional unsteady aerodynamics for idealized wing in pitching and flapping oscillations with phase lag. Parametric study is carried out to obtain the lift, drag, and thrust characteristics within a cycle for assessing the plausibility of the aerodynamic model, and for the synthesis of a Flapping Wing MAV model with simplified mechanism. Other important parameters such as flapping frequency and wing geometry are considered. Results are assessed in comparison with the existing theoretical results.

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