Airplane Wing Research Articles

Planform, aero-structural and flight control optimization for tailless morphing aircraft

Tailless swept wing airplanes rely on variations of the spanwise lift distribution to achieve controllability in all axes. As every flight condition requires different control moments, the conventional discrete control surfaces will be practically continuously deflected, leading to drag penalties. Shape adaptation base on chordwise morphing can achieve continuous deformations of the wing profile, leading to local lift variations with minimum drag penalties. As the shape is varied continuously along the wingspan, the lift distribution can be tailored to each flight condition. Tailless aircraft appear therefore as prime candidates for morphing, as the attainable benefits are potentially significant. This work presents a methodology to determine the optimal planform, profile shape, and morphing structure for a tailless aircraft. The employed morphing concept is based on a distributed compliance structure, actuated by piezoelectric elements. The multidisciplinary optimization considers the static and dynamic aeroelastic behavior of the structure and aims to maximize the aerodynamic efficiency of the plane while guaranteeing its controllability by means of morphing. The potential of the resulting wing design is fully exploited by means of a second optimization process, which identifies the actuation configuration resulting in the highest aerodynamic efficiency for a wide variety of control moments.

Flight envelope expansion based on active mitigation of flutter via a V-stack piezoelectric actuator

The instability of the aircraft’s flexible control surfaces caused by uncontrolled vibrations represents a challenging issue of the aviation security. Flutter is a violent vibration whose amplitude grows strongly in a short time. Once the flutter is reached, the plane is destabilized and it can no longer be controlled. This paper proposes a specially designed demonstrator intended to extend the flight envelope by raising the speed limit at which the flutter occurs. The anti-flutter demonstrator is an intelligent airplane wing model made from a longeron covered by an aerodynamic layer. The wing has an aileron as a primary flight control surface, at one end, and a flange conceived to fix the wing in the aerodynamic tunnel, at the other end. The actuator consists in two V-shaped piezo stacks. The main advantage of the piezo actuator, the bandwidth (about 30 Hz), is exploited. The aero-elastic control is efficient if the deflection of the control surface is of a few degrees while the frequency is of at least 25-30 Hz. The control law is obtained through the receptance method of eigenvalues assignment using the on line input/output measured transfer function rather than the knowledge of system matrices.

Stress-Strain State Exploration of Stringer Made of Composite Materials Depending on Layers Stacking Structure

In this article the results of stress-strain state investigation for composite airplane wing stringer with different layers stacking structures are presented. As an object of research, a stringer made of composite carbon with V-shaped cross-section is considered. Due to the stress-strain state analysis of various stringer structures, the most effective structure for stringer layers stacking is selected, both in the view of providing the most rigidity and optimal perception by the stringer the field of external loads, which are most typical for the conditions of its operation.

Preliminary design of a Tiltwing UAV with a box wing configuration

In the last years, aircraft disruptive configurations have been studied on view to increase civil air transport and safety of flight and, also, to reduce air pollution and noise. One of the promising configurations is the so called box wing, based on the Best Wing System concept by L. Prandtl. This paper presents an application of the box wing to the case of an unconventional Unmanned Air Vehicle (UAV), called "TiltOne", because the two horizontal wings tilt together with the engine-propeller groups, so allowing us to take off and landing vertically and to fly as a fixed wing airplane during cruise. TiltOne is full electric, with distributed propulsion; the preliminary design has been carried out by using a home-made optimization code, where aerodynamics, controls and electric propulsion are taken into account. After defining the airframe configuration, aerodynamic analyses have been performed, electric motors and propellers and batteries are defined; finally, a detailed analysis of the mechanical components is presented and a prototype has been manufactured. Preliminary vertical test flight has been carried out successfully.

Time-series-based nonlinear system identification of strongly nonlinear attachments

This work introduces a new nonlinear system identification procedure for identifying the dynamics of an otherwise linear mechanical system augmented by strongly nonlinear local attachments directly from measured transient response data. The method employs the proper orthogonal decomposition to extract energy-dependent proper orthogonal modes from the measured time series. Then, using known linear properties, the characteristic frequencies of the system are estimated by applying the Rayleigh quotient, and an estimated frequency-energy plot (FEP) is created by plotting the characteristic frequencies as functions of the mechanical energy in the system. The estimated FEP directly reveals the presence of strongly nonlinear modal interactions, in the form of non-smooth perturbations (spikes) that result from transient resonance captures between different harmonic components of the measured data. The nonlinearity is identified by plotting the estimated characteristic frequencies as functions of a defined characteristic displacement and fitting a frequency equation based on the model of the nonlinearity. The method is demonstrated computationally and experimentally using the response of a cantilevered model airplane wing with a strongly nonlinear attachment connected to its tip.

Fourier amplitude sensitivity test applied to dynamic combined finite‐discrete element methods–based simulations

SummaryFracture propagation plays a key role for a number of applications of interest to the scientific community, from dynamic fracture processes like spallation and fragmentation in metals to failure of ceramics, airplane wings, etc. Simulations of material deformation and fracture propagation rely on accurate knowledge of material characteristics such as material strength and the amount of energy being dissipated during the fracture process. Within the combined finite‐discrete element method (FDEM) framework material fracture behavior is typically described through a parametrized softening curve, which defines a stress‐strain relationship unique to each material. We apply the Fourier amplitude sensitivity test to explore how each of these parameters influences the simulated damage processes and to determine the key input parameters that have the most impact on the model response. We present several sensitivity numerical experiments for the simulation of a split Hopkinson pressure bar (SHPB) test for weathered granite samples using different combinations of model parameters. We validate the obtained results against SHPB experimental data. The experiments show that the model is mostly sensitive to parameters related to tensile and shear strengths, even in the presence of other parameter perturbations. The results suggest that the specification of tensile and shear strengths at the interfaces dominate the stress‐time history of the FDEM simulation of SHPB test.

Outstanding superhydrophobicity and corrosion resistance on carbon-based film surfaces coupled with multi-walled carbon nanotubes and nickel nano-particles

In order to solve the problem of poor stability and repeatability of superhydrophobic films to improve its application in industrial production. In this study, nickel nanoparticles and multi-walled carbon nanotubes (MWCNTs) were doped into DLC films for the first time, and a robust superhydrophobic and corrosion resistance nanocomposite MWCNTs-Ni/a-C:H film was prepared via one-step electrochemical deposition under atmospheric pressure and low temperature. The as-prepared film surface had a static water contact angle measured as 158.89° and a sliding angle about 1.99°, which is attributed to the micro-nanoscale hierarchical structure of the film surface. More importantly, the superhydrophobic nanocomposite MWCNTs-Ni/a-C:H film not only shows good mechanical property, but also has outstanding corrosion resistance and excellent self-cleaning ability. This research highlights a promising route for the preparation of robust superhydrophobic film, providing potential uses including self-cleaning, antifouling and anti-corrosion applications such as ship hulls and aeroplane wings.

The Airplane Boneyard Studio: Considering Stillness and Creative Practice from an Airplane Wing

In 1975, Australian artist Ian Howard taped sheets of paper to the nose of the Enola Gay, and through rubbing the surface with a thin layer of wax crayon, he created a ghost-like impression of the airplane that dropped an atomic bomb on Hiroshima. Forty years later, in an aircraft boneyard in Arizona, I placed redundant maps of the Great Sandy Desert on the wing of a passenger jet to take an imprint of a similarly disused yet functionally different aircraft. Despite the conceptual and temporal differences that separated these two acts, the process of rubbing—or frottage—resulted in two artworks that revealed traces of the physical encounter with the aircraft surfaces, the dynamic handling of the materials of making, and the practical and aesthetic impact of working in the field. By its very nature of proximity and touch, the process of frottage records a bodily engagement with both object and environment. Recounting the experiences of working on the wing of a civilian plane in the desert heat of Arizona forty years after Howard worked on the Enola Gay, I reflect on the low-tech process of frottage and its capacity to suggest our respective embodied experiences of making. Furthermore, I suggest that traces of environmental factors such as high humidity, desert winds, or extreme heat, or time-based factors such as limited access to stationary airplanes can be captured and archived through creative practice as a way to contribute to contemporary understandings of mobility and its counterpart stillness.

An Experimental Study and Theoretical Simulation of Jet-Wing Interaction Noise

The use of high-bypass-ratio engines in civil aviation has resulted in the occurrence of an additional noise source associated with noise of interaction between a jet and an airplane wing. A theoretical model is proposed for predicting the characteristics of interaction noise based on the near-field parameters for an isolated jet. The required near-field characteristics were obtained experimentally in the AC-2 anechoic chamber of the Central Aerohydrodynamic Institute (TsAGI) using a system of azimuthal microphone arrays. Noise in the far-field zone was also measured for both an isolated jet and a jet with a closely located plate simulating a wing. The results of comparing the directivities and spectra of interaction noise obtained using the proposed model and measured experimentally are in good agreement.

On the internal architecture of emergent plants

It remains a puzzling issue why and how the organs in plants living in the same natural environment evolve into a wide variety of geometric architecture. In this work, we explore, through a combination of experimental and numerical methods, the biomechanical morphogenesis of the leaves and stalks of representative emergent plants, which can stand upright and survive in harsh water environments. An interdisciplinary topology optimization method is developed here by integrating both mechanical performance and biological constraint into the bi-directional evolutionary structural optimization technique. The experimental and numerical results reveal that, through natural selection over many million years, these leaves and stalks have been optimized into distinctly different cross-sectional shapes and aerenchyma tissues with intriguing anatomic patterns and improved load-bearing performance. The internal aerenchyma is an optimal compromise between the mechanical performance and functional demands such as air exchange and nutrient transmission. We find that the optimal distribution of the internal material depends on multiple biomechanical factors such as the cross-sectional geometry, hierarchical structures, boundary condition, biological constraint, and material property. This work provides an in-depth understanding of the property–structure–performance–function interrelations of biological materials. The proposed topology optimization method and the presented biophysical insights hold promise for designing highly efficient and advanced structures (e.g., airplane wings and turbine blades) and analyzing other biological materials (e.g., bones, horns, and beaks).

Realistic Stacking Sequence Optimisation of an Aero-Engine Fan Blade-Like Structure Subjected to Frequency, Deformation and Manufacturing Constraints

Aims:A procedure to optimise the stacking sequence of a composite fan blade-like structure is proposed in this article. The aim of the optimisation is to minimise weight when respecting deformation, frequency and strain constraints. The literature often deals with stacking sequence optimisation of airplane wings or wind turbine blades whilst less attention has been dedicated to aero-engines fan blades, the objective of the present paper. The manufacturing constraints are also implemented in the optimisation process in order to obtain a manufacturable structure.Background:Stacking sequence of composite laminates can be tailored to drive the deformation towards the desired shape (potentially exploiting unbalanced laminates and their anisotropy). When optimising the stacking sequence (including blending/tapering) of an aero-engine fan blade-like structure, manufacturing constraints must be included in order to apply the results of the optimisation procedure into a “Real World” design.Objectives:To define an engineering procedure able to provide a good design point to minimise the weight of a fan blade-like structure subjected to deformation (tip extension and untwist), frequency and strain constraints.Methods:A two-level optimisation procedure is proposed. At the first level, the stacking sequence is optimised in such a way to maximise stiffness (and therefore to minimise deformation). Less stringent limits are applied to the constraints of such a level 1 optimisation. In the second step of the optimisation, the blending/tapering of each ply of the stacking sequence is searched.Results:The fan blade-like structure is loaded only with a centrifugal load (the main load acting on this kind of components). The stacking sequence obtained to minimise the weight contains 42.3% of 0 degrees fibres, 19.25% of 45 degrees fibres, 19.25% of -45 degrees fibres and 19.2% of 90 degrees fibres. Blending in terms of width and length of each layer is given in the numerical results section.Conclusions:When the fan blade-like structure is loaded with a centrifugal force only, in order to minimise weight by respecting untwist, tip extension, frequency and integrity constraints, no unbalance in the laminate has been found necessary. An “Optimum” point has been found after a two steps optimisation. This design point is claimed as a good industrial design point rather than as “optimum” in the mathematical sense. Such a “Best Solution” design point has been verified by exploring the design space near it. All the performance of the neighbour points has been found worse. A comparison between a quasi-isotropic laminate and a zero degreed dominated laminate has been also performed.

Image-based truss recognition for density-based topology optimization approach

Topology optimization is a tool that supports the creativity of structural-designers and is used in various industries, from automotive to aeronautics, to reduce design iterations towards obtaining the optimal structure layout. However, this tool requires both time and experience to interpret the results into manufacturable and reliable structure layout. To improve this aspect, an interpretation support tool is being developed by our research team based on industrial knowledge and axiomatic design principles. This design tool will be very useful for aircraft structure development, for instance, as it aims to help the structural designer in the conception of stiffened panels. The tool has been divided into three modules: feature recognition, feature analysis and design support. This paper presents the first of the three modules that identifies the trusses of the optimized topology in terms of truss recognition algorithms. The purpose of the truss recognition algorithm is to translate the densities of the element of the optimized topology (low-level abstraction) to a skeletal structure (high-level abstraction) that contains nodes and branches that describe the same topology as the optimized topology. It should also ensure that the structural skeleton retains connectivity with loads and boundary conditions. The information may then be used by the design support tool for analysis, comparison, decision-making, design and optimization purposes. To do so, a novel image-based method using a binary skeleton is proposed. For this work, we identified multiple limitations existing in similar solutions and we mitigated them. Therefore, a new skeletonization method is proposed, which is specifically designed for truss recognition in the optimized topology. The capabilities of the skeletonization method are demonstrated by comparing it with existing methods, and the truss recognition algorithm is used with a test case exhibiting the algorithm’s capabilities on an airplane wing box rib.

Multilevel Nanoparticles Coatings with Excellent Liquid Repellency

AbstractThe excellent liquid repellency surfaces are achieved by using dual‐scale hydrophobic silica coating (d‐HSC) which nanoparticles in xylene‐based suspension without any further modification. The suspension can also be sprayed, dipped, or brushed on substrate to create a transparent superhydrophobic surface. It is demonstrated that the excellent repellency can be achieved for various liquid (e.g., water, milk, coffee, glycerol) as d‐HSC onto copper plate, polyvinyl chloride plate, glass slide, building stone, sponge, and tissue paper. Furthermore, with the addition of silane coupling agent, the d‐HSC shows resilience and maintains its performance to some extent after abrasion with sandpaper. A facile, low‐cost, and effective method to fabricate these multifunctional coatings on versatile substrates is developed without using the common method of fluoride vapor deposition for surface modification. The study is greatly significant for design of robust materials with self‐cleaning, anti‐icing, or waterproof performances that can be extended into application of many aspects (e.g., airplane wing, wall of cooling tower in industry, packing, building, etc.).

Research on Path Loss for an Airplane Wing Wireless Monitoring System

This letter presents the empirical path loss models for the environment of airplane wings. Two wireless prototypes of monitoring-of-airplane-wing (MOAW) at the frequencies of 433, 868, 780, 915, and 2400 MHz band are considered for monitoring wave propagation in a delta airplane wing. The path loss models for the five bands are proposed for spar-mounted, rib-mounted, front-stringer-mounted, and rear-stringer-mounted wireless link scenarios inside an airplane delta wing. Moreover, the packet loss rates of wireless prototypes at five bands inside an airplane wing are investigated. The results of wireless link budget calculations inside an airplane provide insights into how the MOAW devices are deployed inside an airplane wing for constructing better propagation, and give advisable reference to the deployment of devices inside more types of airplane wings in future.

Remote Distributed Vibration Sensing Through Opaque Media Using Permanent Magnets

Vibration sensing is critical for a variety of applications from structural fatigue monitoring to understanding the modes of airplane wings. In particular, remote sensing techniques are needed for measuring the vibrations of multiple points simultaneously, assessing vibrations inside opaque metal vessels, and sensing through smoke clouds and other optically challenging environments. In this paper, we propose a method which measures high-frequency displacements remotely using changes in the magnetic field generated by permanent magnets. We leverage the unique nature of vibration tracking and use a calibrated local model technique developed specifically to improve the frequency-domain estimation accuracy. The results show that two-dimensional local models surpass the dipole model in tracking high-frequency motions. A theoretical basis for understanding the effects of electronic noise and error due to correlated variables is generated in order to predict the performance of experiments prior to implementation. Simultaneous measurements of up to three independent vibrating components are shown. The relative accuracy of the magnet-based displacement tracking with respect to the video tracking ranges from 40 to 190 $\mu \text{m}$ when the maximum displacements approach ±5 mm and when sensor-to-magnet distances vary from 25 to 36 mm. Last, vibration sensing inside an opaque metal vessel and mode shape changes due to damage on an aluminum beam are also studied using the wireless permanent-magnet vibration sensing scheme.

Multi-walled carbon nanotubes enhanced superhydrophobic MWCNTs-Co/a-C:H carbon-based film for excellent self-cleaning and corrosion resistance

A robust superhydrophobic MWCNTs-Co/a-C:H carbon-based film was successfully fabricated for the first time by a safe technology, namely electrochemical deposition. The multi-walled carbon nanotubes (MWCNTs) and Co nano-particles were confirmed to tailor a micro-nanoscale hierarchical surface and nanocrystallite/amorphous microstructure. The resulting MWCNTs-Co/a-C:H carbon-based film exhibited complete water repellency with the contact angle (158.1°) and much smaller sliding angle (2.98°), fairly strong mechanical property, excellent corrosion resistance and self-cleaning ability. This research highlights a promising route for the preparation of robust superhydrophobic film, providing potential uses including self-cleaning, antifouling and anti-corrosion applications such as ship hulls and aeroplane wings.

A novel fractional-order model and controller for vibration suppression in flexible smart beam

Vibration suppression represents an important research topic due to the occurrence of this phenomenon in multiple domains of life. In airplane wings, vibration can cause discomfort and can even lead to system failure. One of the most frequently used means of studying vibrations in airplane wings is through the use of dedicated flexible beams, equipped with sensing and actuating mechanisms powered by suitable control algorithms. In order to optimally reject these vibrations by means of closed-loop control strategies, the availability of a model is required. So far, the modeling of these smart flexible beams has been limited to deliver integer order transfer functions models. This paper, however, describes the mathematical framework used to derive a fractional-order impedance lumped model for capturing frequency response of a flexible beam system exposed to a multisine excitation. The theoretical foundation stems from fractional calculus applied in combination with transmission line theory and wave equations. The simplified model reduces to a minimal number of parameters when converging to a limit value. It is shown that the fractional-order model outperforms an integer order model of the smart beam. Based on this novel fractional-order model, a fractional-order $$\hbox {PD}^\mu $$ controller is then tuned. The controller design is based on shaping the frequency response of the closed-loop system such that the resonant peak is reduced in comparison to the uncompensated smart beam system and disturbances are rejected. Experimental results, considering a custom-built smart beam system, are provided, considering both passive and active control situations, showing that a significant improvement in the closed-loop behavior is obtained using the proposed controller. Comparisons with a fractional-order $$\hbox {PD}^\mu $$ controller, tuned according to classical open-loop frequency domain design specifications, are provided. The experimental results show that the proposed tuning technique leads to similar results as the classical approach. Thus, the proposed method is a viable alternative, being based on closed-loop specifications, which is more intuitive for practitioners.

ОБ ОДНОМ ПОДХОДЕ К ПОСТРОЕНИЮ ХАОТИЧЕСКИХ СИСТЕМ-ХАМЕЛЕОНОВ

Now it is well known that dynamical systems can be categorized into systems with selfexcited attractors and systems with hidden attractors. A self-excited attractor has a basin of attraction that is associated with an unstable equilibrium, while a hidden attractor has a basin of attraction that does not intersect with small neighborhoods of any equilibrium points. Hidden attractors play the important role in engineering applications because they allow unexpected and potentially disastrous responses to perturbations in a structure like a bridge or an airplane wing. In addition, complex behaviors of chaotic systems have been applied in various areas from image watermarking, audio encryption scheme, asymmetric color pathological image encryption, chaotic masking communication to random number generator. Recently so-called chameleons systems have been found out by researchers. These systems were so are named for the reason, that they shows self-excited or hidden oscillations depending on the value of parameters entering into them. In the present work the simple algorithm of synthesizing of oneparametrical chameleons systems is offered. Evolution Lyapunov exponents and Kaplan-Yorke dimension of such systems at change of parameter is traced.

On some dynamical chameleon systems

It is now well known that dynamical systems can be categorized into systems with self-excited attractors and systems with hidden attractors. A self-excited attractor has a basin of attraction that is associated with an unstable equilibrium, while a hidden attractor has a basin of attraction that does not intersect with small neighborhoods of any equilibrium points. Hidden attractors play the important role in engineering applications because they allow unexpected and potentially disastrous responses to perturbations in a structure like a bridge or an airplane wing. In addition, complex behaviors of chaotic systems have been applied in various areas from image watermarking, audio encryption scheme, asymmetric color pathological image encryption, chaotic masking communication to random number generator. Recently, researchers have discovered the so-called “chameleon systems”. These systems were so named because they demonstrate self-excited or hidden oscillations depending on the value of parameters. The present paper offers a simple algorithm of synthesizing one-parameter chameleon systems. The authors trace the evolution of Lyapunov exponents and the Kaplan-Yorke dimension of such systems which occur when parameters change.

This ‘muscular’ mayfly has arms like airplane wings

This ‘muscular’ mayfly has arms like airplane wings