scholarly journals Functionally Graded Flexural Rigidity Improves Flight Performance in Flapping Wing Insects

2021 ◽  
Author(s):  
Joseph Reade ◽  
Mark Jankauski
Keyword(s):  
Power Consumption ◽  
Flexural Rigidity ◽  
Aerodynamic Force ◽  
Flapping Wing ◽  
Functionally Graded ◽  
Muscle Size ◽  
Lattice Method ◽  
Flexible Wing ◽  
Wide Range ◽  
Rigid Wing

AbstractInsect wings are highly heterogeneous structures, with flexural rigidity varying one to two orders of magnitude over the wing surface. This heterogeneity influences the deformation the flapping wing experiences under aerodynamic and inertial loads. However, it is not well understood how this flexural rigidity gradient affects wing performance. Here, we develop a reduced-order model of the flapping wing using the assumed mode method and unsteady vortex lattice method to model the structural and fluid dynamics, respectively. We conduct parameter studies to explore how variable flexural rigidity affects mean lift production, power consumption and the forces required to flap the wing. We find that there is an optimal flexural rigidity distribution that maximizes lift production; this distribution generally corresponds to a 3:1 ratio between the wing’s flapping and natural frequencies, though the precise ratio is sensitive to flapping kinematics. For hovering flapping kinematics, the optimized flexible wing produces 20% more lift and requires 15% less power compared to a rigid wing but needs 20% higher forces to flap. Even when flapping kinematics deviate from those observed during hover, the flexible wing outperforms the rigid wing in terms of aerodynamic force generation and power across a wide range of flexural rigidity gradients. Peak force requirements and power consumption are inversely proportional with respect to flexural rigidity gradient, which presents a trade-off between insect muscle size and energy storage requirements. The model developed in this work can be used to efficiently investigate other spatially variant morphological or material wing features moving forward.

Flexibility of Flapping Rotor Wing and its Effect on Aerodynamic Characteristic

2012 ◽  
Vol 184-185 ◽  
pp. 239-243
Author(s):  
Jing Lu ◽  
Ning Jun Fan ◽  
Yi Wei Wang
Keyword(s):  
Aerodynamic Characteristic ◽  
Aerodynamic Force ◽  
Flapping Wing ◽  
Variable Speed ◽  
New Model ◽  
Flexible Wing ◽  
Wing Model ◽  
Speed Factor ◽  
Rotor Wing ◽  
Rigid Model

In the previous study, the rigid model of flapping wing rotor ignores the flexible factors to describe its in detail. So a new flexible wing model is established here to further study the aerodynamic characteristic of this wing. And a variable-speed factor is taken into account in this new model too. It is found that the deformation position and amplitude are both useful to increase aerodynamic force. The variable-speed factor has a significant effect on aerodynamic characteristic. In the end, the results show the flexible wing has much better performance than rigid one.

Two Architectures for Bending-Twisting Flapping Using Macro-Fiber Composites

2012 ◽  
Author(s):  
Algan Samur ◽  
Alper Erturk
Keyword(s):  
Power Consumption ◽  
Smart Materials ◽  
High Performance ◽  
Fiber Composites ◽  
Flapping Wing ◽  
Light Weight ◽  
Morphing Wing ◽  
Research Fields ◽  
Wide Range ◽  
Dynamic Bending

There has been growing interest in the research fields of morphing-wing and flapping-wing aircraft for improved flight efficiency and maneuverability. Recent efforts have focused on the use of smart materials as actuators in biomimetic morphing and flapping. Macro-Fiber Composites (MFCs) are composed of piezoelectric fibers sandwiched between interdigitated electrodes in addition to Kapton and epoxy laminates. The MFC technology offers effective sensing and actuation with its light weight, high flexibility, durability, high performance, and availability in various sizes. Researchers have studied the use of MFCs in structural health monitoring, vibration control, actuation, and energy harvesting. In the last few years, MFCs have been successfully integrated to morphing-wing aircraft by several others. However, there has been limited work on MFC-based flapping wing by dynamic actuation. The flapping-wing flight is more beneficial than conventional flight at relatively small scales due to its high maneuverability. Biological flapping-wing flyers incorporate different wing motions such as dynamic bending, twisting, and folding to create asymmetry for positive lift and thrust resultants. This paper experimentally characterizes the electroelastic dynamics and power consumption of two MFC-based architectures for bio-inspired flapping. The first configuration employs an asymmetric wide bimorph architecture with 0° and 45° piezoelectric fibers to have an actuation authority in bending and twisting. The second configuration uses a double bimorph arrangement made of two narrow bimorphs with 0° fibers with a chord-wise spacing to create both bending and twisting depending on the relative actuation inputs. Both of the bending-twisting architectures considered herein are tested over a wide range dynamic actuation levels and frequencies to characterize the electroelastic response. In addition to measuring the power consumption levels in dynamic bending and twisting, flexible solar films are investigated as the light-weight multifunctional substructure layers that can create both lift surface and electricity toward the concept of self-powered flapping.

scholarly journals Kinematic Optimization of a Flexible Wing Undergoing Flapping and Pitching

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Yue Wu ◽  
Changchuan Xie ◽  
Yang Meng ◽  
Chao Yang
Keyword(s):  
Aspect Ratio ◽  
Optimization Algorithm ◽  
Flapping Wing ◽  
Flapping Flight ◽  
Propulsive Efficiency ◽  
Flexible Wing ◽  
Passive Deformation ◽  
Kinematic Optimization ◽  
Rigid Wing ◽  
Computational Aeroelasticity

In recent years, there has been widespread interest in the design of microair vehicles (MAVs) for flapping flight with high-aspect ratio wings due to their high efficiency and energy savings. However, the flexibility of a flapping wing causes the aeroelastic effect, which remains a subject of investigation. Generally, existing research simulates active bending and twisting of flexible wings under the assumption of neglecting flapping inertia. In this research, the kinematic optimization of a bionic wing with passive deformation in forward flight while undergoing flapping and pitching is considered. To this end, a computational aeroelasticity framework, which includes the three-dimensional unsteady vortex lattice method (UVLM) and the Newmark-β method, is constructed for flapping flight. Under the assumption of linear elastic deformation, this tool is capable of simulating attached flows over a thin wing and capturing unsteady effects of wakes. A bionic numerical wing with an aspect ratio of 6.5, chord Reynolds number of 1.9 × 105, and reduced frequency less than 0.1 is investigated in kinematic optimization. The computational aeroelasticity framework is combined with a global optimization algorithm to identify the optimal kinematics that maximize the propulsive efficiency under the minimum average lift constraint. Two types of numerical wings, rigid wing and flexible wing, are considered here to compare the influence of deformation on the aerodynamics of the flapping wing. The results show that the aeroelastic effect, which increases the flapping amplitude, yields a significant improvement in terms of propulsive efficiency. In addition, the optimization algorithm maximizes the thrust efficiency while satisfying the required lift. Moreover, the optimal kinematics of both the rigid wing and the flexible wing reach the maximum flapping angle, which indicates that a larger range of motions is needed for optimal kinetics when loosening the boundary conditions.

On the roles of chord-wise flexibility in a flapping wing with hovering kinematics

2010 ◽  
Vol 659 ◽  
pp. 94-115 ◽  
Author(s):  
JEFF D. ELDREDGE ◽  
JONATHAN TOOMEY ◽  
ALBERT MEDINA
Keyword(s):  
Stokes Equations ◽  
Leading Edge ◽  
Relative Sensitivity ◽  
Aerodynamic Performance ◽  
Flexible Wings ◽  
Leading Edge Vortex ◽  
Flexible Wing ◽  
Wide Range ◽  
Edge Vortex ◽  
Rigid Wing

The aerodynamic performance of a flapping two-dimensional wing section with simplified chord-wise flexibility is studied computationally. Bending stiffness is modelled by a torsion spring connecting two or three rigid components. The leading portion of the wing is prescribed with kinematics that are characteristic of biological hovering, and the aft portion responds passively. Coupled simulations of the Navier–Stokes equations and the wing dynamics are conducted for a wide variety of spring stiffnesses and kinematic parameters. Performance is assessed by comparison of the mean lift, power consumption and lift per unit power, with those from an equivalent rigid wing, and two cases are explored in greater detail through force histories and vorticity snapshots. From the parametric survey, four notable mechanisms are identified through which flexible wings behave differently from rigid counterparts. Rigid wings consistently require more power than their flexible counterparts to generate the same kinematics, as passive deflection leads to smaller drag and torque penalties. Aerodynamic performance is degraded in very flexible wings undergoing large heaving excursions, caused by a premature detachment of the leading-edge vortex. However, a mildly flexible wing has consistently good performance over a wide range of phase differences between pitching and heaving – in contrast to the relative sensitivity of a rigid wing to this parameter – due to better accommodation of the shed leading-edge vortex into the wake during the return stroke, and less tendency to interact with previously shed trailing-edge vortices. Furthermore, a flexible wing permits lift generation even when the leading portion remains nearly vertical, as the wing passively deflects to create an effectively smaller angle of attack, similar to the passive pitching mechanism recently identified for rigid wings. It is found that an effective pitch angle can be defined that accounts for wing deflection to align the results with those of the equivalent rigid wing.

scholarly journals Dove: A biomimetic flapping-wing micro air vehicle

2017 ◽  
Vol 10 (1) ◽  
pp. 70-84 ◽  
Author(s):  
Wenqing Yang ◽  
Liguang Wang ◽  
Bifeng Song
Keyword(s):  
Mechanism Design ◽  
Flapping Wing ◽  
Micro Air Vehicle ◽  
Flexible Wing ◽  
The Past ◽  
Ground Station ◽  
Air Vehicle ◽  
Research Goal ◽  
Color Video ◽  
Flapping Mechanism

This paper describes the design and development of the Dove, a flapping-wing micro air vehicle (FWMAV), which was developed in Northwestern Polytechnical University. FWMAVs have attracted international attentions since the past two decades. Since some achievements have been obtained, such as the capability of supporting an air vehicle to fly, our research goal was to design an FWMAV that has the ability to accomplish a task. Main investigations were presented in this paper, including the flexible wing design, the flapping mechanism design, and the on-board avionics development. The current Dove has a mass of 220 g, a wingspan of 50 cm, and the ability of operating fully autonomously, flying lasts half an hour, and transmitting live stabilized color video to a ground station over 4 km away.

Analysis of Residual Stresses on the Vibration of a Circular Sensor Diaphragm with Surface Effects

2016 ◽  
Vol 33 (3) ◽  
pp. 323-329 ◽  
Author(s):  
S.-S. Zhou ◽  
S.-J. Zhou ◽  
A.-Q. Li ◽  
B.-L. Wang
Keyword(s):  
Residual Stresses ◽  
Natural Frequency ◽  
Flexural Rigidity ◽  
Plate Theory ◽  
Surface Elasticity ◽  
Surface Effects ◽  
Transition Range ◽  
Biochemical Sensors ◽  
Tension Parameter ◽  
Wide Range

AbstractResonant micro-biochemical sensors play important roles in a wide range of emerging applications to detect biochemical molecules. As the resonators of micro-biochemical sensors, the vibration characteristics of circular sensor diaphragms are important for the design of diaphragm-based resonant micro-biochemical sensors. In this paper, the influence of residual stresses on the vibration of a circular sensor diaphragm with surface effects is analyzed. Based on the Kirchhoff's plate theory and surface elasticity theory, the governing equation is presented. The material characteristic lengths for different surface effects are obtained. The influences of residual stresses on the effective flexural rigidity and natural frequency of the diaphragm with surface effects are discussed. Results show that the influence of residual stresses on the effective flexural rigidity becomes obvious with the increasing of residual stresses. The first order natural frequency increases rapidly when the tension parameter is larger than 30 for the stiffened surfaces, while for the softened surfaces the value is 10. Moreover, surface effects can influence the transition range of diaphragm from the plate behavior to membrane behavior in terms of the tension parameter. The transition range can be enlarged by the stiffened surface and be shortened by the softened surface. The analysis and results are helpful for the design of sensor diaphragm-based resonant micro-biochemical sensors and some related researches.

scholarly journals An Event-Based, Digital Time Difference Encoder Model Implementation for Neuromorphic Systems

2020 ◽  
Author(s):  
Daniel Gutierrez-galan ◽  
Thorben Schoepe ◽  
Juan Pedro Dominguez-Morales ◽  
Angel Jimenez-Fernandez ◽  
Elisabetta Chicca ◽  
...  
Keyword(s):  
Power Consumption ◽  
Source Localization ◽  
Sound Source ◽  
Digital Circuit ◽  
Temporal Information ◽  
Time Difference ◽  
Digital Implementation ◽  
Wide Range ◽  
Neuromorphic Systems ◽  
Event Based

Neuromorphic systems are a viable alternative to conventional systems for real-time tasks with constrained resources. Their low power consumption, compact hardware realization, and low-latency response characteristics are the key ingredients of such systems. Furthermore, the event-based signal processing approach can be exploited for reducing the computational load and avoiding data loss, thanks to its inherently sparse representation of sensed data and adaptive sampling time. In event-based systems, the information is commonly coded by the number of spikes within a specific temporal window. However, event-based signals may contain temporal information which is complex to extract when using rate coding. In this work, we present a novel digital implementation of the model, called Time Difference Encoder, for temporal encoding on event-based signals, which translates the time difference between two consecutive input events into a burst of output events. The number of output events along with the time between them encodes the temporal information. The proposed model has been implemented as a digital circuit with a configurable time constant, allowing it to be used in a wide range of sensing tasks which require the encoding of the time difference between events, such as optical flow based obstacle avoidance, sound source localization and gas source localization. This proposed bio-inspired model offers an alternative to the Jeffress model for the Interaural Time Difference estimation, validated with a sound source lateralization proof-of-concept. The model has been simulated and implemented on an FPGA, requiring 122 slice registers of hardware resources and less than 1 mW of power consumption.

scholarly journals Investigation on membrane fouling in ultrafiltration of latex solution

2021 ◽  
Author(s):  
Amira Abdelrasoul
Keyword(s):  
Mathematical Model ◽  
Molecular Weight ◽  
Power Consumption ◽  
Membrane Fouling ◽  
Membrane Surface ◽  
Operating Conditions ◽  
Specific Power ◽  
Pore Sizes ◽  
Wide Range ◽  
Different Types

The low-pressure membrane applications are considered to be the most effective and sustainable methods of addressing environmental problems in treating water and wastewater that meets or exceed stringent environmental standards. Nevertheless, membrane fouling is one of the primary operational concerns that is currently hindering a more widespread application of ultrafiltration (UF) with a variety of contaminants. Membrane fouling leads to higher operating costs, higher energy demand, reduced membrane life time, and increased cleaning frequency. As a consequence, an efficient and well-planned UF process is becoming a necessity for consistent and long-term monetary returns. Examining the source and mechanisms of foulant attachment to the membrane’s surface is critical when it comes to the research of membrane fouling and its potential practical implementation. A mathematical model was developed in this study in order to predict the amount of fouling based on an analysis of particle attachments. This model was developed using both homogeneous and heterogeneous membranes, with a uniform and non-uniform pore sizes for the UF of simulated latex effluent with a wide range of particle size distribution. The objective of this mathematical model was to effectively identify and address the common shortcomings of previous fouling models, and to account for the existing chemical attachments in membrane fouling. The mathematical model resulting from this study was capable of accurately predicting the mass of fouling retained by the membrane and the increase in transmembrane pressure (TMP). In addition, predictive models of fouling attachments were derived and now form an extensive set of mathematical models necessary for the prediction of membrane fouling at a given operating condition, as well as, the various membrane surface charges. Polycarbonate and Polysulfone flat membranes, with pore sizes of 0.05 μm and a molecular weight cut off of 60,000 respectively, were used in the experimental designs under a constant feed flow rate and a cross-flow mode in UF of the simulated latex paint effluent. The TMP estimated from the model agreed with the experimentally measured values at different operating conditions, mostly within 5.0 - 8.0 % error, and up to 13.0% error for the uniform, and non-uniform pore size membranes, respectively. Furthermore, different types of membranes with a variety of molecular weight cut-off (MWCO) values were tested so as to evaluate the accuracy of the models for a generalized application. In addition , a power consumption model, incorporating fouling attachment as well as chemical and physical factors in membrane fouling, was developed in order to ensure accurate prediction and scale-up. Innovative remediation techniques were likewise developed and applied in order to minimize membrane fouling, enhance the membrane performance, and save energy. Fouling remediation methodologies included the pre-treating of the latex effluent, so as to limit its fouling propensity by using different types of surfactants as cationic and anionic, in addition to the pH change. The antifouling properties of the membranes were improved through the implementation of the membrane pH treatment and anionic surfactant treatment. Increasing the ionic strength of latex effluent or enhancing the membrane surface hydrophilicity facilitated a significant increase in the cumulative permeate flux, a substantial decrease in the total mass of fouling, and a noticeable decrease in the specific power consumption.

scholarly journals Experimental Study of Rigid and Flexible Tandem Wing for Micro Aerial Vehicle

2021 ◽  
Vol 85 (2) ◽  
pp. 33-43
Author(s):  
Wan Mazlina Wan Mohamed ◽  
Mohd Azmi Ismail ◽  
Muhammad Ridzwan Ramli ◽  
Aliff Farhan Mohd Yamin ◽  
Koay Mei Hyie ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Unmanned Aerial Vehicle ◽  
Lift Coefficient ◽  
Reynolds Numbers ◽  
Micro Aerial Vehicle ◽  
Flexible Wing ◽  
Vehicle Structure ◽  
Aerial Vehicle ◽  
Wing Skin ◽  
Rigid Wing

Unmanned aerial vehicle is becoming increasingly popular each year. Now, aeronautical researchers are focusing on size minimization of unmanned aerial vehicle, especially drone and micro aerial vehicle. The lift coefficient of micro aerial vehicle has wing dimension of 12 cm and mass of less than 7 g. In the present study, with the aid of 3D printer, polylactic acid material was used to develop the micro aerial vehicle structure for tandem wing arrangement. The materials for rigid wing skin and flexible wing skin were laminating film and latex membrane, respectively. The present work elaborates the lift coefficient profiles on rigid wing skin and flexible wing skin at wing flapping frequency of 11 Hz, three different Reynolds numbers of 14000, 19000 and 24000, and five different angles of attacks between 0° and 50°. According to the results obtained, the lift coefficient decreased as the Reynolds number increased. The lift coefficient increased up to 9 as the angle of attack increased from 0° to 50° at the Reynolds number of 14000 for flexible wing skin. The results also showed that the lift coefficient of flexible wing skin was higher than that of rigid wing skin at the attack angle of10° and below, except for the Reynolds number of 14000.

scholarly journals Investigation on membrane fouling in ultrafiltration of latex solution

2021 ◽  
Author(s):  
Amira Abdelrasoul
Keyword(s):  
Mathematical Model ◽  
Molecular Weight ◽  
Power Consumption ◽  
Membrane Fouling ◽  
Membrane Surface ◽  
Operating Conditions ◽  
Specific Power ◽  
Pore Sizes ◽  
Wide Range ◽  
Different Types

The low-pressure membrane applications are considered to be the most effective and sustainable methods of addressing environmental problems in treating water and wastewater that meets or exceed stringent environmental standards. Nevertheless, membrane fouling is one of the primary operational concerns that is currently hindering a more widespread application of ultrafiltration (UF) with a variety of contaminants. Membrane fouling leads to higher operating costs, higher energy demand, reduced membrane life time, and increased cleaning frequency. As a consequence, an efficient and well-planned UF process is becoming a necessity for consistent and long-term monetary returns. Examining the source and mechanisms of foulant attachment to the membrane’s surface is critical when it comes to the research of membrane fouling and its potential practical implementation. A mathematical model was developed in this study in order to predict the amount of fouling based on an analysis of particle attachments. This model was developed using both homogeneous and heterogeneous membranes, with a uniform and non-uniform pore sizes for the UF of simulated latex effluent with a wide range of particle size distribution. The objective of this mathematical model was to effectively identify and address the common shortcomings of previous fouling models, and to account for the existing chemical attachments in membrane fouling. The mathematical model resulting from this study was capable of accurately predicting the mass of fouling retained by the membrane and the increase in transmembrane pressure (TMP). In addition, predictive models of fouling attachments were derived and now form an extensive set of mathematical models necessary for the prediction of membrane fouling at a given operating condition, as well as, the various membrane surface charges. Polycarbonate and Polysulfone flat membranes, with pore sizes of 0.05 μm and a molecular weight cut off of 60,000 respectively, were used in the experimental designs under a constant feed flow rate and a cross-flow mode in UF of the simulated latex paint effluent. The TMP estimated from the model agreed with the experimentally measured values at different operating conditions, mostly within 5.0 - 8.0 % error, and up to 13.0% error for the uniform, and non-uniform pore size membranes, respectively. Furthermore, different types of membranes with a variety of molecular weight cut-off (MWCO) values were tested so as to evaluate the accuracy of the models for a generalized application. In addition , a power consumption model, incorporating fouling attachment as well as chemical and physical factors in membrane fouling, was developed in order to ensure accurate prediction and scale-up. Innovative remediation techniques were likewise developed and applied in order to minimize membrane fouling, enhance the membrane performance, and save energy. Fouling remediation methodologies included the pre-treating of the latex effluent, so as to limit its fouling propensity by using different types of surfactants as cationic and anionic, in addition to the pH change. The antifouling properties of the membranes were improved through the implementation of the membrane pH treatment and anionic surfactant treatment. Increasing the ionic strength of latex effluent or enhancing the membrane surface hydrophilicity facilitated a significant increase in the cumulative permeate flux, a substantial decrease in the total mass of fouling, and a noticeable decrease in the specific power consumption.

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