Nonlinear Aeroelastic Analysis for Highly Flexible Flapping Wing in Hover

2022 ◽  
Author(s):  
Xuan Yang ◽  
Aswathi Sudhir ◽  
Atanu Halder ◽  
Moble Benedict
Keyword(s):  
Structural Model ◽  
Flapping Wing ◽  
Image Correlation ◽  
Elastic Response ◽  
Flapping Wings ◽  
Aerodynamic Model ◽  
Aeroelastic Analysis ◽  
Air Vehicle ◽  
Aeroelastic Simulations ◽  
Nonlinear Fluid

Aeromechanics of highly flexible flapping wings is a complex nonlinear fluid–structure interaction problem and, therefore, cannot be analyzed using conventional linear aeroelasticity methods. This paper presents a standalone coupled aeroelastic framework for highly flexible flapping wings in hover for micro air vehicle (MAV) applications. The MAV-scale flapping wing structure is modeled using fully nonlinear beam and shell finite elements. A potential-flow-based unsteady aerodynamic model is then coupled with the structural model to generate the coupled aeroelastic framework. Both the structural and aerodynamic models are validated independently before coupling. Instantaneous lift force and wing deflection predictions from the coupled aeroelastic simulations are compared with the force and deflection measurements (using digital image correlation) obtained from in-house flapping wing experiments at both moderate (13 Hz) and high (20 Hz) flapping frequencies. Coupled trim analysis is then performed by simultaneously solving wing response equations and vehicle trim equations until trim controls, wing elastic response, inflow and circulation converge all together. The dependence of control inputs on weight and center of gravity (cg) location of the vehicle is studied for the hovering flight case.

Nonlinear Fluid-Elastic Behavior of a Flapping Wing With Low-Order Chord-Wise Flexibility

2020 ◽  
Author(s):  
Dipanjan Majumdar ◽  
Chandan Bose ◽  
Sunetra Sarkar
Keyword(s):  
Structural Model ◽  
Flapping Wing ◽  
Elastic Behavior ◽  
Navier Stokes ◽  
Immersed Boundary ◽  
Stream Velocity ◽  
Aerodynamic Loads ◽  
Flow Parameters ◽  
Coupling Strategy ◽  
Nonlinear Fluid

Abstract The present study attempts to capture the fluid-structure interaction dynamics of a chord-wise flexible flapping wing system using a limited mode structural model coupled with a high-fidelity Navier-Stokes (N-S) solver. The wing is modeled as two elliptic rigid foils connected by a non-linear torsional spring that incorporates the chord-wise bending stiffness. The front link is subjected to an active pitching-plunging motion while the rear link undergoes flow-induced passive oscillation. The structural governing equation for the rear link takes the form of a Duffing equation subjected to base excitation and external aerodynamic forcing. The aerodynamic loads on the foil are computed using a discrete forcing Immersed Boundary Method based in-house N-S solver which is coupled with the structural solver by a staggered weak coupling strategy. A bifurcation study is performed considering the free-stream velocity as the control parameter, in the presence of both structural and aerodynamic non-linearities. A dynamical transition in the unsteady flow-field from a periodic reverse-Kármán wake to an aperiodic wake is observed as the flow parameters are varied. The same transition is also reflected in the passive oscillation of the rear foil when analyzed with tools from the dynamical systems theory.

scholarly journals Multidisciplinary design optimization of the flapping wing system for forward flight

2017 ◽  
Vol 9 (2) ◽  
pp. 93-110
Author(s):  
Jung-Sun Choi ◽  
Gyung-Jin Park
Keyword(s):  
Design Optimization ◽  
Design Process ◽  
Multidisciplinary Design Optimization ◽  
Flapping Wing ◽  
Multidisciplinary Design ◽  
Vehicle Model ◽  
Thrust Coefficient ◽  
Analysis And Design ◽  
Aeroelastic Analysis ◽  
Air Vehicle

The success of a flapping wing air vehicle flight is strongly related to the flapping motion and wing structure. Various disciplines should be considered for analysis and design of the flapping wing system. A design process for a flapping wing system is defined by using multidisciplinary design optimization. Unsteady aeroelastic analysis is employed as the system analysis. From the results of the aeroelastic analysis, the deformation of the wing is transmitted to the fluid discipline and the dynamic pressure is conveyed to the structural discipline. In the fluid discipline, a kinematic optimization problem is solved to maximize the time-averaged thrust coefficient and the propulsive efficiency simultaneously. In the structural discipline, nonlinear dynamic topology optimization is performed to find the distribution of reinforcement by using the equivalent static loads method for nonlinear static response structural optimization. The defined design process is applied to a flapping wing air vehicle model and the flapping wing air vehicle model is fabricated based on the optimization results.

scholarly journals Dipteran wing motor-inspired flapping flight versatility and effectiveness enhancement

2015 ◽  
Vol 12 (104) ◽  
pp. 20141367 ◽  
Author(s):  
R. L. Harne ◽  
K. W. Wang
Keyword(s):  
Structural Model ◽  
Aerodynamic Force ◽  
Flapping Wing ◽  
Flapping Flight ◽  
Axial Stiffness ◽  
Small Scale ◽  
Aerodynamic Efficiency ◽  
Linear Motors ◽  
Air Vehicle ◽  
Compression Characteristics

Insects are a prime source of inspiration towards the development of small-scale, engineered, flapping wing flight systems. To help interpret the possible energy transformation strategies observed in Diptera as inspiration for mechanical flapping flight systems, we revisit the perspective of the dipteran wing motor as a bistable click mechanism and take a new, and more flexible, outlook to the architectural composition previously considered. Using a representative structural model alongside biological insights and cues from nonlinear dynamics, our analyses and experimental results reveal that a flight mechanism able to adjust motor axial support stiffness and compression characteristics may dramatically modulate the amplitude range and type of wing stroke dynamics achievable. This corresponds to significantly more versatile aerodynamic force generation without otherwise changing flapping frequency or driving force amplitude. Whether monostable or bistable, the axial stiffness is key to enhance compressed motor load bearing ability and aerodynamic efficiency, particularly compared with uncompressed linear motors. These findings provide new foundation to guide future development of bioinspired, flapping wing mechanisms for micro air vehicle applications, and may be used to provide insight to the dipteran muscle-to-wing interface.

scholarly journals Three-Dimensional CST Parameterization Method Applied in Aircraft Aeroelastic Analysis

2017 ◽  
Vol 2017 ◽  
pp. 1-15
Author(s):  
Hua Su ◽  
Chunlin Gong ◽  
Liangxian Gu
Keyword(s):  
Structural Model ◽  
Three Dimensional ◽  
Automatic Process ◽  
Shape Transformation ◽  
Design And Optimization ◽  
Aerodynamic Model ◽  
Conceptual Design Phase ◽  
Design Variables ◽  
Aeroelastic Analysis ◽  
Aeroelastic Model

Class/shape transformation (CST) method has advantages of adjustable design variables and powerful parametric geometric shape design ability and has been widely used in aerodynamic design and optimization processes. Three-dimensional CST is an extension for complex aircraft and can generate diverse three-dimensional aircraft and the corresponding mesh automatically and quickly. This paper proposes a parametric structural modeling method based on gridding feature extraction from the aerodynamic mesh generated by the three-dimensional CST method. This novel method can create parametric structural model for fuselage and wing and keep the coordination between the aerodynamic mesh and the structural mesh. Based on the generated aerodynamic model and structural model, an automatic process for aeroelastic modeling and solving is presented with the panel method for aerodynamic solver and NASTRAN for structural solver. A reusable launch vehicle (RLV) is used to illustrate the process for aeroelastic modeling and solving. The result shows that this method can generate aeroelastic model for diverse complex three-dimensional aircraft automatically and reduce the difficulty of aeroelastic analysis dramatically. It provides an effective approach to make use of the aeroelastic analysis at the conceptual design phase for modern aircraft.

scholarly journals Experimental Study on Flexible Deformation of a Flapping Wing with a Rectangular Planform

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Wenqing Yang ◽  
Jianlin Xuan ◽  
Bifeng Song
Keyword(s):  
High Speed ◽  
Aerodynamic Force ◽  
Inertial Force ◽  
Aerodynamic Characteristics ◽  
Flapping Wing ◽  
Image Correlation ◽  
Flapping Wings ◽  
Aerodynamic Forces ◽  
Cyclic Movements ◽  
Flexible Deformation

A flexible flapping wing with a rectangular planform was designed to investigate the influence of flexible deformation. This planform is more convenient and easier to define and analyzed its deforming properties in the direction of spanwise and chordwise. The flapping wings were created from carbon fiber skeleton and polyester membrane with similar size to medium birds. Their flexibility of deformations was tested using a pair of high-speed cameras, and the 3D deformations were reconstructed using the digital image correlation technology. To obtain the relationship between the flexible deformation and aerodynamic forces, a force/torque sensor with 6 components was used to test the corresponding aerodynamic forces. Experimental results indicated that the flexible deformations demonstrate apparent cyclic features, in accordance with the flapping cyclic movements. The deformations in spanwise and chordwise are coupled together; a change of chordwise rib stiffness can cause more change in spanwise deformation. A certain lag in phase was observed between the deformation and the flapping movements. This was because the deformation was caused by both the aerodynamic force and the inertial force. The stiffness had a significant effect on the deformation, which in turn, affected the aerodynamic and power characteristics. In the scope of this study, the wing with medium stiffness consumed the least power. The purpose of this research is to explore some fundamental characteristics, as well as the experimental setup is described in detail, which is helpful to understand the basic aerodynamic characteristics of flapping wings. The results of this study can provide an inspiration to further understand and design flapping-wing micro air vehicles with better performance.

scholarly journals Quad-thopter: Tailless flapping wing robot with four pairs of wings

2018 ◽  
Vol 10 (3) ◽  
pp. 244-253 ◽  
Author(s):  
Christophe De Wagter ◽  
Matěj Karásek ◽  
Guido de Croon
Keyword(s):  
Micro Air Vehicles ◽  
Flapping Wing ◽  
Micro Air Vehicle ◽  
Flapping Wings ◽  
Flight Tests ◽  
Wind Gusts ◽  
Air Vehicle ◽  
Differential Thrust ◽  
Yaw Moment ◽  
Novel Design

We present a novel design of a tailless flapping wing micro air vehicle, which uses four independently driven pairs of flapping wings in order to fly and perform agile maneuvers. The wing pairs are arranged such that differential thrust generates the desired roll and pitch moments, similar to a quadrotor. Moreover, two pairs of wings are tilted clockwise and two pairs of wings anti-clockwise. This allows the micro air vehicle to generate a yaw moment. We have constructed the design and performed multiple flight tests with it, both indoors and outdoors. These tests have shown the vehicle to be capable of agile maneuvers and able to cope with wind gusts. The main advantage is that the proposed design is relatively simple to produce, and yet has the capabilities expected of tailless flapping wing micro air vehicles.

Measurement of Flapping Wing Deformation Using Piezoelectric Modal Sensors

2016 ◽  
Author(s):  
Jason Tran ◽  
Christopher G. Cameron ◽  
Jayant Sirohi
Keyword(s):  
Accurate Method ◽  
Flapping Wing ◽  
Image Correlation ◽  
Flapping Wings ◽  
Full Field ◽  
Measured Deformation ◽  
Wing Deformation ◽  
Deformation Measurements ◽  
Dic Technique ◽  
Good Agreement

An experimental investigation was conducted to measure the deformation of flapping wings with distributed piezoelectric modal sensors. The sensors are bonded to the surface of a wing and shaped to extract a specific modal co-ordinate. The experimental setup consisted of a carbon fiber beam with shaped sensors designed to extract the 1st and 2nd modal co-ordinates. The beam was mounted to two different excitation devices (shaker or servomotor) that allowed the beam to be excited at a desired frequency and motion. The resulting electrical signals from the strained modal sensors are calibrated to modal co-ordinate measurements. In order to validate modal sensor measurements, the Digital Image Correlation (DIC) technique is used to obtain full field deformation measurements of the beam. The measured deformation from DIC is then used in conjunction with operational modal analysis to extract modal co-ordinates. Comparison of the modal co-ordinates obtained via modal sensors against DIC measurements show good agreement. Furthermore, a sensitivity analysis was performed to gauge the robustness of modal sensors against construction errors. The results obtained show that modal sensors are a simple and accurate method of obtaining the deformation of a flapping wing.

Design and Analysis of Flapping Wing

2011 ◽  
Vol 110-116 ◽  
pp. 3495-3499
Author(s):  
G.C. Vishnu Kumar ◽  
M. Rahamath Juliyana
Keyword(s):  
Experimental Data ◽  
Flapping Wing ◽  
Micro Air Vehicle ◽  
Flapping Wings ◽  
Visualization Technique ◽  
Aerodynamic Forces ◽  
Flapping Motion ◽  
Smoke Flow ◽  
Air Vehicle ◽  
Lift And Drag

This paper the optimum wing planform for flapping motion is investigated by measuring the lift and drag characteristics. A model is designed with a fixed wing and two flapping wings attached to its trailing edge. Using wind tunnel tests are conducted to study the effect of angle of attack (smoke flow visualization technique). The test comprises of measuring the aerodynamic forces with flapping motion and without it for various flapping frequencies and results are presented. It can be possible to produce a micro air vehicle which is capable of stealthy operations for defence requirements by using these experimental data.

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