Control Surface Research Articles

ОГЛЯД ДОСЛІДЖЕНЬ ТА ОБҐРУНТУВАННЯ НОВИХ МАТЕМАТИЧНИХ МЕТОДІВ МОДЕЛЮВАННЯ АЕРОПРУЖНОСТІ КРИЛА З ЛЮФТОМ КЕРУЮЧИХ ПОВЕРХОНЬ

The phenomenon of instability in flight due to the interaction of aerodynamic, elastic and inertial forces. could prove disastrous. Therefore, due importance is given to the aeroelastic analysis of the aircraft at the design stage. Free play, sometimes called play, occurs as a result of wear on parts such as lugs or moving mounts, often due to the aging of the aircraft. Excessive free play is detrimental to the flight safety of the aircraft. This can lead to catastrophic aeroelastic instabilities such as limit cycle oscillation (LCO), a phenomenon associated with sustained vibration of a fixed amplitude. LCO can accelerate the accumulation of structural fatigue damage and compromise controllability during flight. Aircraft control systems play a critical role in ensuring stability, maneuverability and flight safety. Over the past few decades, nonlinear aeroelasticity has received increasing attention. Advanced computational capabilities have stimulated renewed interest among researchers in re-examining the control surface free play problem with the goal of refining analytical models for greater accuracy. Both modern theoretical and experimental analyzes of free play have opened up new possibilities for the study of aeroelasticity. Despite the apparent understanding of the fundamental problem and the availability of numerous modeling approaches, freewheeling research continues to generate varied predictions regarding aeroelastic dynamic behavior and associated properties. Free play, defined as the sag or movement of mechanical connections between control inputs and aircraft control surfaces, is a ubiquitous aspect of control system design. While a little play may be tolerable, excessive play can lead to non-linearities and uncertainties, potentially compromising flight performance and safety. The aim of the article is to review existing methods of numerical research, analyze new mathematical methods for modeling aeroelastic vibrations and formulate the problem of developing safety criteria for transport category aircraft in terms of preventing elastic instability in the presence of free play in the control mechanism.

Surface characteristics of resin composite cores and bond strength to CAD/CAM resin matrix glass-ceramic restorations after different treatment protocols.

The purpose of this study was to evaluate the impact of various mechanical surface treatments on thesurface roughness and microtensile bond strength (µTBS) of aged composite resin cores bonded to CAD/CAM restorations. Composite resin specimens (Filtek Z350 XT, 3M-ESPE/Solventum) were thermally aged and subsequently divided into four groups (n = 36) according to surface treatments: UI-cleaning with ultrasonic diamond tip; AO-sandblasting with 50µm Al2O3; DB-cleaning with diamond burs; and CG-positive control group, without aging or surface treatment. Surface roughness was assessed using a profilometer and interferometer, with measurements taken on both sides of each specimen (n = 12). The surface characteristics were further analyzed through scanning electron microscopy (SEM) (n = 12). In addition, PMMA blocks were temporarily cemented (n = 12) onto the resin blocks, and after surface treatments, resin matrix glass-ceramic blocks were adhesively luted with dual-cure resin cement (RelyX Ultimate, 3&nbsp;M-ESPE/ Solventum, St. Paul, MN, USA) to the resin composite substrates. The CG specimens were adhesively luted to the indirect restorations without temporary restorations or surface treatment. After luting, the specimens were sectioned and tested for µTBS. The results (p = 0.05) from the profilometry and interferometry analyses indicated the highest surface roughness values for the DB group, followed by AO, UI, and CG. SEM analysis revealed marked morphological differences among the groups. Regarding µTBS, the GC specimens (25.78 ± 5.70MPa) and UI specimens (25.56 ± 11.36MPa) exhibited statisticallysimilar values, which were superior to those of the AO (12.25 ± 4.34MPa) and DB (13.16 ± 5.59MPa) groups (p < 0.001), which showed comparable results. In conclusion, the use of ultrasonic diamond tips resulted in the most favorable outcomes in terms of cleaning effectiveness, surface roughness, and bond strength among the surface treatments analyzed for resin composite cores.

Toxic layering and compound extremes: Per- and polyfluoroalkyl substances (PFAS) exposure in rural, environmental justice copper mining communities

Per- and polyfluoroalkyl substances (PFAS) are pervasive environmental pollutants with significant impacts on ecosystems and public health. This study aimed to characterize PFAS concentrations in an environmental justice community impacted by active/legacy copper mining, compounded by wildfires and flash floods. Additionally, the study explored the (re)mobilization of PFAS and co-occurrence with metal(loid)s following these events. Twenty-eight PFAS compounds in 35 residential and 8 control surface soil samples were analyzed via liquid chromatography-tandem mass spectrometry (LCMS/MS). The maximum total PFAS concentration observed in the residential samples was 96.40 μg kg−1, compared to 1.69 μgkg−1 in the control samples. Perfluorobutanoic acid (PFBA) had a maximum concentration of 61 μg kg−1 in residential samples, while Perfluorohexane sulfonic acid (PFHxS) had the highest concentration in the control samples at 0.92 μg kg−1. Long-chain PFAS were most dominant in this study. Perfluorooctane sulfonic acid (PFOS) (58 % of the samples), Perfluorooctanoic acid (PFOA) (35 %), and Perfluorohexane sulfonic acid (PFHxS) (72 %) exceeded the U.S. EPA Soil-to-Groundwater Risk-Based Screening Levels, highlighting the potential risk of contaminants migrating from soil to groundwater, which could ultimately impact groundwater quality. Co-occurrence analysis showed that increases in PFAS concentrations were positively associated with Zn (β = 1.25, p = 0.0034) and Ba (β = 1.23, p = 0.0284) but negatively associated with Pb (β = −0.83, p = 0.0115) and Co (β = −1.38, p = 0.04671). In general, a spatial distribution map indicated that greater PFAS concentrations were observed near potential sources i.e., active mines. This evidence combined with select metal co-occurrence highlights the potential role of mining activities on PFAS concentration.

Insights into the relationship between regulation of oxygen vacancy and singlet oxygen generation in peracetic acid activation

Peracetic acid (PAA) has shown good potential in advanced oxidation techniques, but the mechanism regulating the generation of non-radical species in peracetic acid has not been clarified. Herein, Ov-Co3O4/C-x was prepared by pyrolysis of ZIF-L precursors at different temperatures to achieve the regulation of oxygen vacancy concentration and used for the degradation of sulfamethazine (SMT) by activated PAA. When x = 350 °C, the prepared Ov-Co3O4/C-350 with the highest oxygen vacancy content had the highest SMT removal efficiency and the highest rate constant(kobs), which degraded SMT by 99.6 % within 30 min. The role of oxygen vacancies(OVs) on the surface of Ov-Co3O4/C-350 was investigated using quenching experiments, Electron Paramagnetic Resonance (EPR) and X-ray Photoelectron Spectroscopy (XPS) techniques. The results showed that oxygen vacancy on the metal oxide surface can be converted into more reactive oxygen(O*), and surface OVs of Ov-Co3O4/C-350 enable efficient capture of PAA, thus generating 1O2 and R-O•. The higher the content of oxygen vacancies is, the more 1O2 is produced, while concentration of R-O• was not significantly correlated with oxygen vacancy content. Furthermore, the degradation pathway of SMT was predicted through density functional theory (DFT) calculations and identifications of intermediates, indicating that electron-rich sites such as aromatic rings and S-N bonds in the SMT molecule are more easily oxidized by reactive species. Besides, due to the low biotoxicity of the degradation products of the Ov-Co3O4/C-350/PAA system, the reaction can effectively reduce the biotoxicity and developmental toxicity. This study provides a controllable surface property strategy for a new idea in PAA-based AOP.

Uncertainty analysis of rudder shaft thermal conditions on the flutter characteristics of the hypersonic control surface

The thermal conditions in hypersonic aerothermoelastic systems exert a significant influence on the flutter characteristics of the system. Nevertheless, in previous investigations on aeroelastic uncertainty analysis, the influence of thermal uncertainty has frequently been neglected. In this study, an uncertainty analysis framework based on Monte Carlo simulation and surrogate model is conducted for addressing the thermal uncertainty and its implications on the flutter characteristics. Initially, the all-moving control surface of a hypersonic vehicle is selected as the investigated model. A parametric method is then developed to represent the temperature distribution along the control rudder shaft, taking into account the temperature conditions calculated by CFD. Based on the approach, the impact of temperature uncertainty is designed to perform the uncertainty quantification of temperature uncertainty on flutter characteristics of the control surface. Sensitivity indices are computed to evaluate the impact of temperature uncertainty in different regions of the shaft on flutter characteristics. This implies BPNN always provides accurate models. This is not always true and even if it is, showing that in a general sense is not within the scope of this study. Furthermore, the temperature uncertainty on the shaft surface induces uncertainty in the modal frequencies of the control surface, thereby resulting in uncertain flutter characteristics. Notably, the leading-edge region of the shaft exhibits the most pronounced effect on flutter characteristics, followed by the midsection region. These results could offer valuable insights for the refined design of control surfaces in hypersonic vehicles, contributing to the advancement of this field of research.

Modulation on Surface Termination Groups to Optimize the Adsorption Energy and Work Function of Nb2CTx for Enhanced Hydrogen Storage in Magnesium Hydride

AbstractExploring high‐performance catalysts for hydrogen storage in magnesium hydride (MgH2) is crucial but still a challenge. Herein, Nb2CTx with controllable surface termination groups is developed as an efficient catalyst and the bifunctional modulation (adsorption energy and work function) of different surface termination groups (F, O, OH, or defects) is explored. First, compared to F and O, the introduction of OH on the surface or the direct removal of functional groups both leads to a significant increase in the adsorption of H by Nb2CTx. Second, compared to the surface bare, OH‐rich Nb2CTx has a lower work function, making it easier for hydrogen to enter Mg/MgH2 from the Nb2CTx surface or escape from the Mg/MgH2 surface into the Nb2CTx, thus facilitating the hydrogen ad/desorption properties of MgH2, i.e., the rate‐determining step (RDS) shifts from penetration to diffusion. The Nb2CTx‐KOH‐catalyzed MgH2 with optimal surface termination groups, therefore exhibits a release of 6.56 wt.% H2 in 5 min at 250 °C, and 6.46 wt.% H2 uptake within 5 min at 150 °C. The dehydrogenation and hydrogen uptake activation energies show 49.5% and 60.1% enhancements over pristine MgH2. In addition, a storage capacity of 5.51 wt.% is maintained after 50 dehydrogenation/hydrogenation cycles.

One-step on-chip preparation of nanoparticle-conjugated red blood cell carriers

Red blood cell (RBC)-based carriers have emerged as promising vehicles for drug delivery due to their inherent biocompatibility and biodegradability. Traditional methods for loading nanoparticles (NPs) onto RBC surfaces often involve labor-intensive processes like incubation and multiple centrifugation steps, limiting their practicality and controllability. In this study, we introduce a fully integrated acoustofluidic platform that enables one-step preparation of NP-loaded RBC carriers with controlled modification and on-site purification. By incorporating a high-frequency bulk acoustic wave (BAW) resonator into a microfluidic chip, we utilize acoustic streaming effects to manipulate the movement and interaction of RBCs and NPs within the microchannel. This design allows for precise control over NP loading efficiency by adjusting the input power to the resonator. Experimental results using 200 nm positively charged fluorescent NPs demonstrate that our platform significantly enhances the interaction between RBCs and NPs, achieving efficient and controllable surface loading of NPs onto RBCs. Furthermore, the platform simplifies post-processing by directing excess NPs to waste outlets, eliminating the need for repetitive washing and centrifugation. This acoustofluidics approach not only automates the loading process but also offers high controllability, highlighting its potential for various applications in particle and cell surface modification.

Controllable p-type doping and improved conductance of few-layer WSe2 via Lewis acid

Manipulation of the electronic properties of layered transition-metal dichalcogenides (TMDs) is of fundamental significance for a wide range of electronic and optoelectronic applications. Surface charge transfer doping is considered to be a powerful technique to regulate the carrier density of TMDs. Herein, the controllable p-type surface modification of few-layer WSe2by FeCl3Lewis acid with different doping concentrations have been achieved. Effective hole doping of WSe2has been demonstrated using Raman spectra and XPS. Transport properties indicated the p-type FeCl3surface functionalization significantly increased the hole concentration with 1.2 × 1013cm-2, resulting in 6 orders of magnitude improvement for the conductance of FeCl3-modified WSe2compared with pristine WSe2. This work provides a promising approach and facilitate the further advancement of TMDs in electronic and optoelectronic applications.

Unveiling Biodiesel Production: Exploring Reaction Protocols, Catalysts, and Influential Factors

AbstractAn environmentally responsible and sustainable replacement for finite fossil fuels is biodiesel. Because of its amazing qualities, biodiesel is becoming more and more popular as a renewable fuel around the globe. The many approaches, feedstocks, catalysts, comparison standards, reaction kinetics, final product analysis, and final product characterization of biodiesel are covered in this review article. Researchers have used a variety of techniques to produce biodiesel throughout history, with transesterification emerging as the most effective approach in more recent times. Numerous studies on biodiesel feedstock and catalysts to produce high biodiesel yields have been published; nevertheless, it should be highlighted that the type of feedstock must be considered while choosing a catalyst. The review paper highlights the significance of several parameters that are crucial to the manufacture of biodiesel, without which achieving a high yield would be challenging. The literature has also discussed the limitations and advantages of different catalysts, and scientists are currently working to identify the ideal catalyst within certain optimal parameters for the manufacture of biodiesel. Homogeneous reaction‐based biodiesel synthesis has a number of drawbacks, though, such as water content, a laborious purification procedure, and a low tolerance for free fatty acids. To address these issues, scientists have started investigating heterogeneous reactions involving solid catalysts. A large pore network, a moderate‐to‐high density of strong acid sites, a hydrophobic surface, and the ability to control surface hydrophobicity to avoid deactivation are all desirable characteristics of an ideal solid catalyst. Ion exchange resins, sulfated oxides, heterogeneous base catalysts, boron group‐based heterogeneous catalysts, alkaline earth metal oxides, mixed metal oxides, alkali metal oxides, heterogeneous catalysts derived from waste materials, and different approaches to biodiesel synthesis that employ enzymes, carbon‐based heterogeneous catalysts, and ionic liquids as catalysts are among the categories of catalysts that can be used in the production of biodiesel. The finest benchmarks to compare the quality of biodiesel with European and American Society for Testing Material standards. For detailed characterization of the finished product, gas chromatography and nuclear magnetic resonance are the most effective methods.

Study on type of magnetic suspension rotor groove and wear of drop touchdown bearing

The active magnetic bearing (AMB) is widely used in the field of flywheel energy storage system (FESS) in wind power generation. This study mainly studies the magnetic suspension rotor groove (MSRG) of FESS and the wear of drop touchdown bearing (DTB). The mathematical model of air gap magnetic field waveform on stator surface and Plath equation of control in air gap region were established. Contrastive analysis of conventional, second harmonic and third harmonic ‘petal-shaped’ MSRG in AMB. The life test of DTB on magnetic suspension rotor was carried out for 24000r/min and lasted for 1500 h. The second harmonic ‘petal-shaped’ MSRG could not only generate reluctance torque and increased the torque density of the motor, but also increased the fundamental component and excitation torque component by reducing the peak value of the magnetic field. The temperature ranges of front and rear DTB were ‘30℃–46℃’ and ‘26℃–40℃’, respectively. After service, the maximum thickness of metamorphic layer in the DTB raceway was 6 μm. After service, the content of Fe in the metamorphic layer of DTB raceway decreased by 10.11% and the content of C increased by 2.41%. Raceway hardness of DTB after service was 59.67 HV higher than that before service.

Titanium Surface Synergy: Strontium Incorporation and Controlled Disorder Nanotopography Optimize Osteoinduction.

Osteoporotic fractures and arthritis represent a major socioeconomic health burden. Fragility fracture fixation and joint replacement are often undertaken using titanium (Ti) or Ti alloy implants. Ideally these should induce bone formation and reduce osteoclast formation. Nanoscale topographies are potent inducers of osteogenesis, and strontium (Sr) has both osteogenic and antiosteoclastic effects. We incorporated strontium into a titanium surface with an osteogenic disordered nanoscale topography. The surface comprises 120 nm diameter, 100 nm deep pits in a near-square order with deliberate offset from the center pit position up to ±50 nm, providing a pattern with an average center-center pit spacing of 300 nm (called near-square 50, NSQ50). Several surfaces were assessed, including NSQ50 alone, strontium incorporated alone, and combined, compared with control surfaces. We assessed the surfaces using a human bone marrow stromal cell (BMSC)/ bone marrow hematopoietic cell (BHSC) coculture capable of osteogenesis and osteoclastogenesis. The samples eluted Sr over long-term culture, and uptake of Sr was better with eluted Sr than with Sr added to the culture media. The NSQ50 pattern in Ti was osteogenic, and addition of Sr elution increased osteogenesis further for both flat and NSQ50 samples. Interestingly, BMSCs on all Ti samples did not secrete the receptor activator of nuclear factor kappa-Β ligand (RANKL) or macrophage colony-stimulating factor (M-CSF) while secreting osteoprotegrin (OPG) at high levels. This meant that no osteoclast formation was observed on any Ti surface. Therefore, using Sr-incorporated nanotopographical imprinting, we generated highly osteogenic Ti surfaces that inhibited osteoclast formation.

Microfluidic Synthesis of Magnetic Nanoparticles for Biomedical Applications.

Magnetic nanoparticles have attracted great attention and become promising candidates in the biomedicine field due to their special physicochemical properties. They are generally divided into metallic and non-metallic magnetic nanoparticles, according to their compositions. Both of the two types have shown practical values in biomedicine applications, such as drug delivery, biosensing, bioimaging, and so on. Research efforts are devoted to the improvement of synthesis strategies to achieve magnetic nanoparticles with controllable morphology, diverse composition, active surface, or multiple functions. Taking high repeatability, programmable operation, precise fluid control, and simple device into account, the microfluidics system can expand the production scale and develop magnetic nanoparticles with desired features. This review will first describe different classifications of promising magnetic nanoparticles, followed by the advancements in microfluidic synthesis and the latest biomedical applications of these magnetic nanoparticles. In addition, the challenges and prospects of magnetic nanoparticles in the biomedical field are also discussed.

Clickable Plastic Surfaces with Controllable Azide Surface Density

AbstractThis study investigates the surface functionalization of plastic substrates through dip‐coating in azide‐functionalized polymer solutions, followed by a click reaction (i.e., strain‐promoted azide–alkyne cycloaddition). Acrylic, poly(ethylene terephthalate) (PET), and nylon substrates are dip‐coated with a series of polymers containing various azide groups grafted onto the poly(methyl methacrylate‐co‐hydroxyethyl methacrylate) backbone to examine structural effects on the surface density of clickable azide groups. X‐ray photoelectron spectroscopy and fluorescence spectroscopy confirm the subsequent click‐immobilization of cycloalkyne‐tagged fluorescein, which is quantified to calculate the surface density of clickable azide groups. Further investigations demonstrate that the surface density of azide groups can be controlled by manipulating the polymer ratio during dip‐coating, thus enabling the preparation of a linear surface gradient in terms of azide group density. Finally, the microcontact printing (µCP) method is employed to pattern the functionalized surfaces and quantify the functional molecules immobilized on the surface by µCP. This study highlights the adaptability of click chemistry and polymer coating techniques for the advanced functionalization of plastic surfaces for materials science and engineering applications.

Uncertainty analysis of hypersonic flight dynamics under elastic effects

Abstract In addressing the aerodynamic-elastic coupling issues of hypersonic vehicles, this study delves into the analysis of the elastic deformation of the aircraft based on mechanistic understanding. It employs the Interval Analysis Method based on Polynomial Approximations to conduct uncertainty analysis of the aerodynamic model under elasticity, delineating the range of uncertainty in the aerodynamic model influenced by elastic deformation. The aerodynamic force of the aircraft under elasticity is connected with the rigid body, and then the aerodynamic layout of the aircraft fuselage and control surface after elastic deformation is calculated to study the influence of the elastic effect on the aerodynamic force. The results show that the change caused by uncertainty has a relatively small effect on lift but a relatively large effect on drag and pitching moment.

Intelligent control algorithms to ensure the flight safety of aerospace vehicles

An overview of the architectures, functions and algorithms of aircraft-type aerospace vehicles equipped with fly-by-wire (FBW) digital integrated control systems (ICS) is given. The ICS has a hierarchical architecture, including the primary, backup and emergency control systems with a sophisticated control reconfiguration logic in the event of failures. Digital control computers have dissimilar redundancy of equipment and software. At the atmospheric flight stage, integrator control laws provide the specified control characteristics, flight envelope protection, automatic trim of vehicle and crew workload alleviation. Further integration of manual and automatic control, implementation of the control philosophy as a continuation of the pilot's actions, more intellectual control system and human-machine interface, use of multiple control surfaces to ensure optimal vehicle configuration and alleviate structural loading together with basic control functions are considered as promising areas for ICS improvement.

Induced-Strain Actuators for Morphing of Multi-Element Airfoils

A multi-objective optimization framework is developed to examine the capabilities of surface-mounted piezocomposites for camber morphing of multi-element airfoils for various sizes of aircraft. A parameterized piezocomposite-actuated airfoil concept, along with associated modeling and analysis methods, is presented for determining the static aeroelastic response of a morphing multi-element airfoil. The optimization algorithm is also presented for determining airfoil parameters for meeting an arbitrary mission objective. The optimization capability is demonstrated using a multi-element airfoil to produce high-lift control surface geometries. A model-scale prototype is designed based on the optimization and fabricated for experimental testing to validate the design framework and provide confidence for full-scale analysis. Full-scale morphing capability is examined using commercially available piezocomposite actuators for a small passenger jet, clearly quantifying the limitations of induced-strain actuation at large aerodynamic loading and Reynolds numbers. Additional design optimizations are conducted and presented with a so-called “vision” actuator that is not available today; however, it may become available in the future. It is shown that strain-induced actuation for large aircraft may become reality in the future with reasonable developments in smart materials.

An Automated Computational Fluid Dynamics Workflow for Simulating the Internal Flow of Race Car Radiators

In this article, we present a software tool developed in Python, named T-WorkFlow. It has been devised to meet some of the design needs of Tatuus Racing S.p.a., a leading company in the design and production of racing cars for the FIA Formula 3 Regional and Formula 4 categories. The software leverages the open-source tools OpenFOAM and FreeCAD to fully automate the fluid dynamics simulation process within car radiators. The goal of T-WorkFlow is to provide designers with precise and easily interpretable results that facilitate the identification of the geometry, ensuring optimal flow distribution in the radiator channels. T-WorkFlow requires the radiator’s geometry files in .stp and .stl formats, along with additional user inputs provided through a graphical interface. For mesh generation, the software leverages the OpenFOAM tools blockMesh and snappyHexMesh. To ensure uniform mesh quality across different configurations, and thus, comparable numerical results, various pre-processing operations on the specific geometry files are needed. After generating the mesh, T-WorkFlow automatically defines a control surface for each radiator channel to monitor the volumetric flow rate distribution. This is achieved by combining the OpenFOAM command topoSet with specific geometric information directly obtained from the radiator’s CAD through FreeCAD. During the simulation, the software provides various outputs that automate the main post-processing operations, enabling quick and easy identification of the configuration that ensures the desired performance.

Experimental Investigation of Biofouled Ship Control Surface Performance

Abstract Marine biofouling threatens ship safety by causing unexpected control surface performance. To explore these adverse biofouling effects, this paper presents the results of wind tunnel testing using a model-scale, low aspect ratio NACA 0018 control surface. Simulated calcareous biofouling was introduced as coarse-grit sandpaper, and, uniquely, roughness locations and sandpaper grits were varied to better understand any resulting degradation in hydrodynamic performance. Direct experimentation at high (turbulent) chord Reynolds number values suggests that leading-edge biofouling with 36-grit sandpaper results in worst-case performance, with the control surface's average lift-to-drag ratio reduced by 63%. Additional findings are presented, and recommendations for future experimental work are also provided.

A Comparative Analysis of Active Control vs. Folding Wing Tip Technologies for Gust Load Alleviation

As part of the Ultra High Aspect Ratio Wing Advanced Research and Designs (U-HARWARD) project, funded by CS2JU, various gust load alleviation (GLA) technologies have been developed and studied. GLA plays a crucial role in the development of new generation ultra-high aspect ratio wings (UHARWs), as it reduces gust loads, thereby decreasing the structural weight of the wing and, consequently, the entire aircraft. This weight reduction enhances overall aircraft efficiency, enabling a higher aspect ratio. GLA technologies are categorized into passive systems, which require no active intervention, and active systems, where control surfaces redistribute the aerodynamic loads. In this study, passive GLA was implemented using a folding wing tip (FWT) developed by the University of Bristol, while active GLA employed a Static Output Feedback controller developed by Politecnico di Milano. Both approaches were compared against a baseline aircraft configuration. A flutter assessment confirmed that FWT does not introduce aeroelastic instabilities, ensuring the aircraft remains flutter-free across its flight envelope. A thorough comparison of load envelopes, based on nearly 2000 load cases across different flight points and mass configurations, was conducted in compliance with CS25 regulations, examining both positive and negative gust conditions. The results show a possible 15% reduction in the dynamic load envelope for both passive and active solutions. Using NeOPT, a hybrid finite element (FE) model was developed, with a detailed global FEM (GFEM) for the wingbox and stick elements for other components. Linear gust analyses in Nastran, with the hinge locked and released, provided high-fidelity results, comparing wing failure indexes and demonstrating the effectiveness of the FWT solution.

Data-driven flutter suppression of noised airfoil models: model identification and robust sliding mode control designed with multi-level control surfaces

Data-driven flutter suppression of noised airfoil models: model identification and robust sliding mode control designed with multi-level control surfaces