Rosario Pecora | Università degli Studi di Napoli "Federico II" (original) (raw)

Journal Articles by Rosario Pecora

Applied Sciences, 2022

The mitigation of seismic-induced vibrations is essential for the effective protection of buildin... more The mitigation of seismic-induced vibrations is essential for the effective protection of buildings and occupants during earthquakes. This especially applies to slender buildings with metallic frames; in this case, the structure’s geometrical layout and relatively low damping properties favor an excessive and potentially catastrophic oscillatory response to a seismic event. Semiactive systems for energy dissipation are among the most commonly used strategies to control this oscillatory response. They offer the right balance between the reliability of passive devices and the versatility and adaptability of fully active systems. In this work, a vibration-suppression system based on dissipative bracings that integrate commercial magnetorheological fluid dampers (MRDs) was designed and validated through experimental tests on a true-scale structural model that was representative of a five-story slender building with a metallic frame. A practical and robust approach was proposed for: (1) The definition of the MRD type in compliance with a predefined mitigation target for seismic-induced accelerations on each floor of the structure; (2) The modeling of the MRDs, contribute to the dynamic response of the structural system. The approach involves a linearized formulation of the characteristic damping curves of the MRDs at different values of the activating current. By relying upon this linearization, a rapidly converging iterative process was set up to simulate the seismic response of the structure in the case of activated or deactivated dampers. The reference structure and the vibration-suppression system were then manufactured and tested on a sliding table, which provided realistic seismic excitation. The good correlation levels between the numerical predictions and the experimental measurements proved the effectiveness of the conceived system and of the approaches that were used for its design and simulation.

Biomimetics, 2021

In a previous paper, the authors dealt with the current showstoppers that inhibit commercial appl... more In a previous paper, the authors dealt with the current showstoppers that inhibit commercial applicability of morphing systems. In this work, the authors express a critical vision of the current status of the proposed architectures and the needs that should be accomplished to make them viable for installation onboard of commercial aircraft. The distinction is essential because military and civil issues and necessities are very different, and both the solutions and difficulties to be overcome are
widely diverse. Yet, still remaining in the civil segment, there can be other differences, depending on the size of the aircraft, from large jets to commuters or general aviation, which are classifiable in tourism, acrobatic, ultralight, and so on, each with their own peculiarities. Therefore, the paper aims to trace a common technology denominator, if possible, and envisage a future perspective of actual applications.

Applied Sciences, 2021

Aircraft winglets are well-established devices that improve aircraft fuel efficiency by enabling ... more Aircraft winglets are well-established devices that improve aircraft fuel efficiency by enabling a higher lift over drag ratios and lower induced drag. Retrofitting winglets to existing aircraft also increases aircraft payload/range by the same order of the fuel burn savings, although the
additional loads and moments imparted to the wing may impact structural interfaces, adding more weight to the wing. Winglet installation on aircraft wing influences numerous design parameters and requires a proper balance between aerodynamics and weight efficiency. Advanced dynamic
aeroelastic analyses of the wing/winglet structure are also crucial for this assessment. Within the scope of the Clean Sky 2 REG IADP Airgreen 2 project, targeting novel technologies for next-generation regional aircraft, this paper deals with the integrated design of a full-scale morphing
winglet for the purpose of improving aircraft aerodynamic efficiency in off-design flight conditions, lowering wing-bending moments due to maneuvers and increasing aircraft flight stability through morphing technology. A fault-tolerant morphing winglet architecture, based on two independent and asynchronous control surfaces with variable camber and differential settings, is presented. The system is designed to face different flight situations by a proper action on the movable control tabs. The potential for reducing wing and winglet loads by means of the winglet control surfaces is numerically assessed, along with the expected aerodynamic performance and the actuation systems’ integration in the winglet surface geometry. Such a device was designed by CIRA for regional aircraft installation, whereas the aerodynamic benefits and performance were estimated by ONERA on the natural laminar flow wing. An active load controller was developed by PoliMI and UniNA
performed aeroelastic trade-offs and flutter calculations due to the coupling of winglet movable harmonics and aircraft wing bending and torsion.

Applied Sciences, 2021

Oleo-pneumatic landing gear is a complex mechanical system conceived to efficiently absorb and di... more Oleo-pneumatic landing gear is a complex mechanical system conceived to efficiently absorb and dissipate an aircraft’s kinetic energy at touchdown, thus reducing the impact load and acceleration transmitted to the airframe. Due to its significant influence on ground loads, this system is gen-erally designed in parallel with the main structural components of the aircraft, such as the fuselage and wings. Robust numerical models for simulating landing gear impact dynamics are essential from the preliminary design stage in order to properly assess aircraft configuration and structural arrangements. Finite element (FE) analysis is a viable solution for supporting the design. However, regarding the oleo-pneumatic struts, FE-based simulation may become unpractical, since detailed models are required to obtain reliable results. Moreover, FE models could not be very versatile for accommodating the many design updates that usually occur at the beginning of the landing gear project or during the layout optimization process. In this work, a numerical method for simulating oleo-pneumatic landing gear drop dynamics is presented. To effectively support both the pre-liminary and advanced design of landing gear units, the proposed simulation approach rationally balances the level of sophistication of the adopted model with the need for accurate results. Alt-hough based on a formulation assuming only four state variables for the description of landing gear dynamics, the approach successfully accounts for all the relevant forces that arise during the drop and their influence on landing gear motion. A set of intercommunicating routines was im-plemented in MATLAB® environment to integrate the dynamic impact equations, starting from user-defined initial conditions and general parameters related to the geometric and structural configuration of the landing gear. The tool was then used to simulate a drop test of a reference landing gear, and the obtained results were successfully validated against available experimental data.

Chinese Journal of Aeronautics, 2021

SARISTU was a big cooperation project granted by the European Commission, 7th Framework Programme... more SARISTU was a big cooperation project granted by the European Commission, 7th Framework Programme, carried out between 2011 and 2015. It dealt with smart aeronautic structures, both morphing and sensored; its main target was to demonstrate the feasibility of designing, manufacturing and operating in representative environment, instrumented structures. Till now, it represents the major effort carried out within the European Union on the development of adaptive architectures for air systems. Inside that big activity, the realization of an adaptive trailing edge device (ATED) for wing camber adaptations aimed at compensating the weight reduction following the fuel consumption during cruise was addressed. It made the core of investigations targeting variable geometry aircraft components together with two other analyses concerning the development of shape-changing winglet and droop nose. ATED activities were conducted by the Italian Aerospace Research Centre (CIRA) in tight cooperation with the University of Napoli, “Federico II”, who coordinated a group of 12 different partners from 8 different Nations (France, Germany, Greece, the Netherlands, Israel, Spain, Turkey, and Italy). In this paper, an integral synthesis of that work is reported, with a focus on the definition and realization of the components of the presented device. The publication is in fact meant as the first part of a series that aims at overviewing the whole Adaptive Trailing Edge development, till wind tunnel tests execution. Such a concise report is a critical and harmonized review of what performed by many col-leagues spread all over Europe, all of which are duly recalled in the reported bibliography where the reader may access more detailed information and descriptions.
In detail, the paper starts with a general introduction of the concept and its aims, to move to the specs definition immediately after. Then, it deals with a short but comprehensive description of the main ATED components: structural skeleton, skin, actuation and sensing systems. It is worth to remark that the paragraph dedicated to the body frame includes some discussion about aeroelastic assessment and manufacture, seen as complementary for a complete assessment of the design constraints.

Chinese Journal of Aeronautics, 2021

Morphing wing structures are widely considered among the most promising technologies for the impr... more Morphing wing structures are widely considered among the most promising technologies for the improvement
of aerodynamic performances in large civil aircraft. The controlled adaptation of the wing shape to external
operative conditions naturally enables the maximization of aircraft aerodynamic efficiency, with positive fallouts
on the amount of fuel burned and pollutant emissions. The benefits brought by morphing wings at aircraft level are
accompanied by the criticalities of the enabling technologies, mainly involving weight penalties, overconsumption
of electrical power, and safety issues. The attempt to solve such criticalities passes through the development of
novel design approaches, ensuring the consolidation of reliable structural solutions that are adequately mature for
certification and in-flight operations. In this work, the development phases of a multimodal camber morphing wing
flap, tailored for large civil aircraft applications, are outlined with specific reference to the activities addressed by
the author in the framework of the Clean Sky program.
The flap is morphed according to target shapes depending on aircraft flight conditions and defined to enhance
high-lift performances during takeoff and landing, as well as wing aerodynamic efficiency during cruise. An
innovative system based on finger-like robotic ribs driven by electromechanical actuators is proposed as
morphing-enabling technology; the maturation process of the device is then traced from the proof of concept to the
consolidation of a true-scale demonstrator for pre-flight ground validation tests. A step-by-step approach involving
the design and testing of intermediate demonstrators is then carried out to show the compliance of the adaptive
system with industrial standards and safety requirements. The technical issues encountered during the development
of each intermediate demonstrator are critically analyzed, and justifications are provided for all the adopted
engineering solutions. Finally, the layout of the true-scale demonstrator is presented, with emphasis on the
architectural strengths, enabling the forthcoming validation in real operative conditions.

Aerospace, 2019

The application of morphing wing devices can bring several benefits in terms of aircraft performa... more The application of morphing wing devices can bring several benefits in terms of aircraft performance, as the current literature shows. Within the scope of Clean Sky 2 AirGreen 2 European project, the authors provided a safety-driven design of an adaptive winglet, through the examination of potential hazards resulting from operational faults, such as actuation chain jamming or links structural fails. The main goal of this study was to verify whether the morphing winglet systems could comply with the standard civil flight safety regulations and airworthiness requirements (EASA CS25). Systems functions were firstly performed from a quality point of view at both aircraft and subsystem levels to detect potential design, crew and maintenance faults, as well as risks due to the external environment. The severity of the hazard effects was thus identified and then sorted in specific classes, representative of the maximum acceptable probability of occurrence for a single event, in association with safety design objectives. Fault trees were finally developed to assess the compliance of the system structures to the quantitative safety requirements deriving from the Fault and Hazard Analyses (FHAs). The same failure scenarios studied through FHAs have been simulated in flutter analyses performed to verify the aeroelastic effects due to the loss of the actuators or structural links at aircraft level. Obtained results were used to suggest a design solution to be implemented in the next loop of design of the morphing winglet.

Aeronautical Journal, 2019

This paper deals with the actuation system design of a full-scale morphing aileron for regional a... more This paper deals with the actuation system design of a full-scale morphing aileron for regional aircraft. The aileron is allowed to smoothly change its geometrical configuration and perform the in-flight transition from a baseline shape to a set of optimal morphed ones pre-defined
on the basis of aerodynamic requirements. The design of such innovative aileron is aimed not only at substituting the conventional aileron installed on a real aircraft but also to provide additional functionality. The aileron is free to rotate around its main hinge axis and it is also allowed to smoothly modify camber with two independent actuation systems. In such a manner it can be used also during cruise with a symmetric deflection between the two half wings in order to reduce drag in off design condition. To accomplish variable aileron shape, a rigid-body mechanism was designed. The proposed aileron architecture is characterised by segmented adaptive ribs rigidly linked each other with spanwise reinforcements such as spars and stringers in a multi-box arrangement. Each rib is split into two movable plates connected by means of rotational hinges in a finger-like mechanism. The mechanism is driven by a load-bearing actuator by means of a kinematic chain opportunely tied based on the structural requirements in terms of shape to be matched and load to be withstood. The proposed device
is an innovative arrangement of the quick-return mechanism composed of a beam leverage, commercial linear guides and a crank. The actuator shaft is directly inserted in the crank, which transmits the rotation to the linear guide that slide along a rail moving upward or downward the beam thus resulting in a camber variation. The entire aileron is moved by three
leverages internally contained and distributed along the first two bays while the most external ribs are considered passive and their movement slaved. Two actuation layouts are analytically and numerically studied, the analytical theory is presented and validated by means of a
multi-body simulation. Moreover, a linear static analysis was carried out under the hypothesis of glued contact between linear guides components simulating a jamming condition. This assumption has been formulated because it represents the most severe condition that envelop
all the operative loads to which the actuation system is subjected. The analyses conducted are preliminarily aimed to verify that no failure occurs under the imposed loads. In this first design loop, the vertical static force acting on the linear carriage exceeded allowable value and then a new configuration with double-sided linear guides was then investigated.

MDPI-Aerospace, Feb. 19, 2019

Nature has many striking examples of adaptive structures: the emulation of birds' flight is the t... more Nature has many striking examples of adaptive structures: the emulation of birds' flight is the true challenge of a morphing wing. The integration of increasingly innovative technologies, such as reliable kinematic mechanisms, embedded servo-actuation and smart materials systems, enables us to realize new structural systems fully compatible with the more and more stringent airworthiness requirements. In this paper, the authors describe the characterization of an adaptive structure, representative of a wing trailing edge, consisting of a finger-like rib mechanism with a highly deformable skin, which comprises both soft and stiff parts. The morphing skin is able to follow the trailing edge movement under repeated cycles, while being stiff enough to preserve its shape under aerodynamic loads and adequately pliable to minimize the actuation power required for morphing. In order to properly characterize the system, a mock-up was manufactured whose structural properties, in particular the ability to carry out loads, were also guaranteed by the elastic skin. A numerical sensitivity analysis with respect to the mechanical properties of the multi-segment skin was performed to investigate their influence on the modal response of the whole system. Experimental dynamic tests were then carried out and the obtained results were critically analysed to prove the adequacy of the adopted design approaches as well as to quantify the dissipative (high-damping) effects induced by the rubber foam on the dynamic response of the morphing architecture.

Aerospace Science and Technologies, 2019

The Adaptive Trailing Edge Device (ATED) was a sub-project inside SARISTU (Smart Intelligent Airc... more The Adaptive Trailing Edge Device (ATED) was a sub-project inside SARISTU (Smart Intelligent Aircraft Structures, 2011–2015), an L2 level project of the 7th EU Framework programme coordinated by Airbus, aimed at developing technologies for realizing a morphing wing for the improvement of general aircraft performance. That study, divided into design, manufacturing and testing phases, involved universities, research centers and leading industries of the European consortium. The aim of the present work is to predict the aero-servo-elastic impact of a full-scale morphing wing trailing edge on a CS-25 category aircraft. Within SARISTU, many FE models were realized, taking into account the complete and complex adaptive wing structure behavior. Those numerical representations referred to the 5.5 m wing section that was then employed for wind tunnel tests; such segment included the winglet and was representative of the outer wing segment (namely, the so-called “aileron region”). Those models were taken as reference to develop numerical representation of the considered wing that better suited the complete wing segment, from the fuselage attachment to the end of the flap region. Therefore, a scaling process was necessary, aimed at translating the former architectures to the new geometries. This kind of extrapolation had the advantage to take into account larger rooms to host the complex actuator system with all its components. MSC Nastran®FE models were elaborated to estimate stiffness and inertial distributions that allowed constructing the stick-beam mock-up of the complete structure. Several cases of flutter analysis were investigated by an in-house code, SANDY 3.0, to verify the safety requirements imposed by the applicable aviation regulations (paragraph 25.629, parts a and b-1). Moreover, dynamic stability assessment was performed with respect to single and combined failures of the actuation line and kinematic chain enabling morphing in order to support FHA (Fault and Hazard Analysis).

International Journal of Mechanical Engineering and Robotics Research, 2019

Modern aerospace research programs are increasingly focusing on structural design strategies base... more Modern aerospace research programs are increasingly focusing on structural design strategies based on the adaptive wing philosophy. Morphing wing technologies are being studied because they can be used to maximize the aerodynamic efficiency, maneuverability, and load control effectiveness under different flight conditions. As one of the most important research projects in Europe, the JTI Green Regional Aircraft (GRA) focused on the design and demonstration of a true-scale morphing flap applicable to the natural laminar flow (NLF) wing of a 130-seat EASA CS25 category reference aircraft. The authors worked on developing an appropriate actuation and control system to enable flap bi-modal operational modes. In the deployed configuration, the overall camber morphs during take-off and landing for high-lift performances. In the stowed configuration, the flap trailing edge (nearly 10% of the local chord) is deflected upwards and downwards to improve the wing aerodynamic efficiency during cruising. Tailored control units were programmed according to a proper digital logic control law based on LTI DriveManager® software. Flap functionality tests showed that the obtained morphed shapes had an excellent correlation with the design target geometries.

Journal of Aerospace Engineering, Mar 1, 2019

When dealing with adaptive lifting surfaces, the level of complexity of the structural design nat... more When dealing with adaptive lifting surfaces, the level of complexity of the structural design naturally increases as a consequence of the augmented functionality of the resulting system. Specifically, an adaptive structure ensures a controlled and fully reversible transition from a baseline shape to a set of different configurations, each one characterized by different external loads and transmission paths of the internal stresses. The Consortium de recherche et d'innovation en aérospatiale au Québec (CRIAQ) MD0-505 research project, born from an efficient transatlantic cooperation among Italian and Canadian academic departments, research centers, and leading companies, suggests a possible solution to more stringent government requirements on emissions and safety: an innovative morphing aileron implemented to increase both structural stability and the in-cruise load control, was designed, manufactured, and tested. The aim of this article is to predict the aero-servo-elastic impact of a true-scale prototype on a regional aircraft, following an experimental test campaign and the development of a well-correlated finite-element model of the device. A detailed trade-off flutter analysis was performed by means of SANDY, an in-house code, in compliance with European Aviation Safety Agency (EASA) CS-25 airworthiness requirements and referring - initially - to nominal aileron functioning. Furthermore, a sensitivity investigation was carried out to assess the dynamic stability of the adaptive aileron, verifying the flutter clearance in the presence of critical scenarios related to malfunctions of the actuation system. Safety values for the aileron control harmonic were investigated looking at potential certification and industrialization issues.

MDPI-Aerospace, Jan 24, 2019

Within the framework of the Clean Sky-JTI project the design and technological demonstration of a... more Within the framework of the Clean Sky-JTI project the design and technological demonstration of a novel wing flap architecture were addressed. Research activities were carried out to substantiate the feasibility of morphing concepts enabling flap camber variation in compliance with the demanding safety requirements applicable to the next generation green regional aircraft. The driving motivation for the investigation on such a technology, was found in the opportunity to replace a conventional double slotted flap with a single slotted camber-morphing flap assuring similar high lift performances -in terms of maximum attainable lift coefficient and stall angle- while lowering emitted noise and system complexity. The actuation and control logics aimed at preserving prescribed geometries of the device under variable load conditions are numerically and experimentally investigated with reference to an “iron-bird” demonstrator. The actuation concept is based on load-bearing actuators acting on morphing ribs, directly and individually. The adopted un-shafted distributed electromechanical system arrangement uses brushless actuators, each rated for the torque of a single adaptive rib of the morphing structure. An encoder-based distributed sensor system generates the information for appropriate control-loop and, at the same time, monitors possible failures in the actuation mechanism. Further activities were then discussed in order to increase the TRL of the validated architecture.

MDPI-Aerospace, Nov 16, 2018

Modern transport aircraft wings have reached just near-peak levels of energy-efficiency and there... more Modern transport aircraft wings have reached just near-peak levels of energy-efficiency and there is still margin for further and relevant improvements. A promising strategy for improving aircraft efficiency is to change the shape of the aircraft wing in flight in order to maximize its aerodynamic performance under all operative conditions. In the present work, that has been developed in the framework of Clean Sky 2 (REG-IADP) European research project, the authors focused on the design of a multifunctional twistable trailing-edge for a Natural Laminar Flow (NLF) wing. Multifunctional wing trailing-edge is used to improve aircraft performances during climb and off-design cruise conditions in response to variations in speed, altitude and other flight parameters. The investigation domain of the novel full-scale device covers 5.15 meters along the wing span and the 10% of the local wing chord. Concerning the wing trailing-edge, the preliminary structural and kinematic design process of the actuation system is completely addressed: three rotary brushless motors (placed in root, central and tip sections) are required to activate the inner mechanisms enabling different trailing-edge morphing modes. The structural layout of the thin-walled closed-section composite trailing-edge represents a promising concept meeting both the conflicting requirements of load-carrying capability and shape adaptivity. Actuation system performances and aeroelastic deformations, considering both operative aerodynamic and limit load conditions, prove the potential of the proposed structural concept to be energy efficient, and lightweight for real aircraft implementation. Finally, the performance assessment of the outer natural laminar flow (NLF) wing retrofitted with the multifunctional trailing-edge is performed by high-fidelity aerodynamic analyses. For such NLF wing, this device can improve airplane aerodynamic efficiency during high speed climb conditions.

Smart Materials and Structures, Sep 18, 2018

Aircraft industry is by now deeply involved in technological breakthroughs bringing innovative fr... more Aircraft industry is by now deeply involved in technological breakthroughs bringing innovative frameworks, in which the morphing systems constitute the most promising scenario. These systems are taking a remarkable role among the unconventional solutions for the improvement of performance in the operating conditions. The application of morphing devices involves a combination among structural and aerodynamic analyses, actuation requirements, weight assessment and flight control performance. The research project CRIAQ-MDO505, Canadian-European cooperation project on smart technologies, has investigated morphing structures potential through the design and the manufacturing of a variable camber aileron tailored to CS-25 category aircraft applications. This paper is especially focused on the most considerable results able to validate the conceptual design: functionality, ground vibration and wind tunnel tests outcomes have been discussed. The ailerons typically constitute crucial elements for the aerodynamic forces equilibrium of the wing. Therefore, compared to the traditional architectures, the need of studying the dynamic performance and the following aeroelastic impact is, in the specific case of servo-actuated variable-shaped systems, higher. Relying upon the experimental evidence within the present research, the issue appeared concerns the critical importance of considering the dynamic modelling of the actuators in the design phase of a smart device. The higher number of actuators and mechanisms involved makes de facto the morphing structure much more complex. In this context, the action of the actuators has been modelled within the numerical model of the aileron: the comparison between the modal characteristics of numerical predictions and testing activities has shown a high level of correlation. Moreover, the compliance of the device with the design morphing shapes has been proved by wind tunnel test. The outcomes are expected to be key insights for future designers to better comprehend the dynamic response of a morphing aileron, primary knowledge for flutter and failure analyses.

Aeronautical Journal, 2018

A new wing-tip concept with morphing upper surface and interchangeable conventional and morphing ... more A new wing-tip concept with morphing upper surface and interchangeable conventional and morphing ailerons was designed, manufactured, bench and wind-tunnel tested. The development of this wing-tip model was performed in the frame of an international CRIAQ project, and the purpose was to demonstrate the wing upper surface and aileron morphing capabilities in improving the wing-tip aerodynamic performances. During numerical optimisation with 'in-house' genetic algorithm software, and during wind-tunnel experimental tests, it was demonstrated that the air-flow laminarity over the wing skin was promoted, and the laminar flow was extended with up to 9% of the chord. Drag coefficient reduction of up to 9% was obtained when the morphing aileron was introduced. Copyright © Royal Aeronautical Society 2018.

International Journal of Mechanical Engineering and Robotics Research, 2018

In the framework of Clean Sky 2 Airgreen 2 GRA ITD project, this paper deals with the design proc... more In the framework of Clean Sky 2 Airgreen 2 GRA ITD project, this paper deals with the design process of a morphing winglet for a regional aircraft. By improving A/C aerodynamic efficiency in off-design flight conditions, the morphing winglet is expected to operate during long (cruise) and short (climb and descent) mission phases to reduce aircraft drag and optimize lift distribution, while providing augmented roll and yaw control capability. The mechanical system is designed to face different flight situations by a proper action on the movable parts represented by two independent and asynchronous control surfaces with variable camber and differential settings. A set of suitable electromechanical actuators are integrated within the limited space inside the winglet loft-line, capable of holding prescribed deflections for long time operations. Such a solution mitigates the risks associated with critical failure cases (jamming, loss of WL control) with beneficial impacts on A/C safety. Numerical details on the system architecture and ability to cope with the typical mission loads profiles are given, along with a description of the conceptual analysis and the expected system performance according to a suitable metric. © 2018 Int. J. Mech. Eng. Rob. Res.

International Journal of Mechanical Engineering and Robotics Research, 2017

In last decades, several research programs were founded worldwide to exploit the potentialities o... more In last decades, several research programs were founded worldwide to exploit the potentialities of the morphing concepts, especially to improve aerodynamic efficiency, and so reduce fuel consumption. Among these, the CRIAQ MDO-505 project represents the first joined research program between Canadian and Italian academies, research centers and leading industries. The aim of the project is to design, manufacture and tests in wind tunnel facilities a morphing wing tip for a Bombardier-type aircraft controlled by electric actuators and pressure sensors. In such framework, the authors intensively worked on the flutter clearance demonstration of the wind tunnel wing model equipped with a full-scale variable-camber aileron driven by load-bearing electro-mechanical actuators. Rational approaches were implemented in order to simulate the effects induced by variations of aileron actuator's stiffness on the aeroelastic behavior of the wing. Reliable models were properly implemented to enable fast aeroelastic analyses covering several configuration cases in order to prove clearance from any dynamic instability (flutter) up to 1.2 times the maximum flow speed expected during Wind Tunnel Tests. Finite-element models were properly developed in order to obtain and implement wing model modal parameters (modes shapes, frequencies, generalized masses, damping) in SANDY®, an in-house developed code, that was used for the definition of the coupled aero-structural model as well as for the solution of aeroelastic stability equations by means of theoretical modes association in frequency domain. Obtained results were finally arranged in a diagram showing trend of the flutter speed with respect to changes in control surface harmonic covering a wide range of values for the stiffness of the aileron (external) actuator. © 2017 Int. J. Mech. Eng. Rob. Res.

Journal of Intelligent Material Systems and Structures, 2017

Trailing edge modification is one of the most effective ways to achieve camber variations. Usual ... more Trailing edge modification is one of the most effective ways to achieve camber variations. Usual flaps and aileron implement this concept and allow facing the different needs related to take-off, landing, and maneuver operations. The extension of this idea to meet other necessities, less dramatic in terms of geometry change yet useful a lot to increase the aircraft performance, moves toward the so-called morphing architectures, a compact version of the formers and inserted within the frame of the smart structures’ design philosophy. Mechanic (whether compliant or kinematic), actuation and sensor systems, together with all the other devices necessary for its proper working, are embedded into the body envelope. After the successful experiences, gained inside the SARISTU (SmARt Intelligent Aircraft STrUctures) project where an adaptive trailing edge was developed with the aim of compensating the weight variations in a medium-size commercial aircraft (for instance, occurring during cruise), the team herein exploits the defined architecture in the wing of a typical airfoil, used on high-altitude long-endurance aircraft such as the Global Hawk. Among the peculiarities of this kind of aerial vehicle, there is the long endurance, in turn, associated with a massive fuel storage (approximately around 50% of the total weight). A segmented, finger-like, rib layout is considered to physically implement the transition from the baseline airfoil to the target configurations. This article deals with an extensive estimation of the possible benefits related to the implementation of this device on that class of planes. Parametric aerodynamic analyses are performed to evaluate the effects of different architectural layouts (in-plane geometry extension) and different shape envelopes (namely, the rotation boundaries). Finally, the expected improvements in the global high-altitude long-endurance aircraft performance are evaluated, following the implementation of the referred morphing device. © 2017, © The Author(s) 2017.

Composite Structures, 2017

In this work, a structural health monitoring system has been implemented with damage identificati... more In this work, a structural health monitoring system has been implemented with damage identification purpose on a winglet of a general aviation aircraft. Using a pitch-catch approach, guided waves (Lamb waves) have been measured by means of an array of piezoelectric sensors able to excite and record the dynamic response of the structure. The undamaged configuration has been used as reference state (baseline) for the structural health monitoring (SHM) purpose while the damaged configuration (current state) has been obtained by low velocity impact test. The effectiveness of the damage has been verified using a Non-Destructive Inspection (NDI) by means of a C-SCAN Olympus Omni SX. The calculation of the damage index obtained comparing the measured wave propagation data in a reference state and the current state is introduced as a determinant of structural damage. Its calculation in different paths associated with the Probability Ellipse (PE) method has been used to identify the position of the damage. Additional radar graphs have been developed for the measurement of the directionality of the Lamb waves and further considerations have been introduced in order to evaluate the sensitivity of the Lamb waves with the aerodynamic load. © 2016 Elsevier Ltd

Applied Sciences, 2022

Biomimetics, 2021

Applied Sciences, 2021

Chinese Journal of Aeronautics, 2021

Aerospace, 2019

Aeronautical Journal, 2019

MDPI-Aerospace, Feb. 19, 2019

Aerospace Science and Technologies, 2019

International Journal of Mechanical Engineering and Robotics Research, 2019

Journal of Aerospace Engineering, Mar 1, 2019

MDPI-Aerospace, Jan 24, 2019

MDPI-Aerospace, Nov 16, 2018

Smart Materials and Structures, Sep 18, 2018

Aeronautical Journal, 2018

International Journal of Mechanical Engineering and Robotics Research, 2018

International Journal of Mechanical Engineering and Robotics Research, 2017

Journal of Intelligent Material Systems and Structures, 2017

Composite Structures, 2017

AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2022 (San Diego - CA, USA), 2022

This paper offers an overview of the Project of AIRGREEN2 (AG2, Clean Sky 2), in terms of main ta... more This paper offers an overview of the Project of AIRGREEN2 (AG2, Clean Sky 2), in terms of main targets, technology development and maturation path, current achievements and further steps and perspective. Starting from the industrial and scientific scenario in which AG2 was conceived, outlining the specific way it meets the current market and environmental requirements, the general structure is illustrated, paying attention to the specific validation gates and demonstration test campaigns. The paper then continues with an overview of the last achievements, encompassing the ground tests of an adaptive winglet and of an innovative wingtip, the finalization of a wind tunnel campaign for aeroelastic validation and the realization of morphing device models, for the upcoming wind tunnel tests on a flexible and laminar wing model. Finally, the next steps of the research are introduced, with specific reference to the ground test of a multifunctional flap, the execution of the just mentioned wind tunnel demonstration on a laminar, flexible and morphing wing, and the final flight demonstration of the winglet and of the wingtip.

AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2022 (San Diego - CA, USA), 2022

This paper summarizes the results of the design study and provides a description of three morphin... more This paper summarizes the results of the design study and provides a description of three morphing wing devices developed for a turboprop regional aircraft in the framework of the Clean Sky 2 REG-IADP Airgreen 2 project. In sinergy with a natural laminar flow wing, morphing wing technologies are investigated to improve both high-lift performance and aerodynamic efficiency in off-design conditions of the aircraft, by demonstrating also load control and alleviation capabilities over the flight envelope. The combined use of a deformable droop nose and a multifunctional morphing flap, designed by PoliMi and UniNA respectively, is able to meet the minimum high-lift performance requirement of the AG2-NLF aircraft for both take-off and landing conditions. The controlled flap is deployed during take-off by using a fairingless concept, totally hosted in the wing, that offers additional benefits on structural weight and aerodynamic efficiency at high speed. The flap camber is then morphed to gain the extra lift required for landing operations. An adaptive winglet concept, designed by CIRA, is also presented to further enhance aircraft aerodynamic efficiency also in climb/descent conditions by lowering at the same time wing-bending moments due to aircraft maneuvers. Such a mechanical system is characterized by two movable surfaces aimed at performing variable camber and differential tab settings depending on the flight conditions. Both aerodynamic performance and benefits of the three morphing devices are assessed by ONERA on the natural laminar flow wing.

AIAA Science and Technology Forum and Exposition, AIAA SciTech Forum 2022 (San Diego - CA, USA), 2022

An innovative adaptive architecture was defined for the wing flap of a large civil transport airc... more An innovative adaptive architecture was defined for the wing flap of a large civil transport aircraft with the scope of improving high-lift performances and wing efficiency in cruise. The adaptation of the flap shape follows three different morphing modes and is ensured by a smart
robotic structure driven by electric actuators combined with powerful transmission lines. For robotic morphing architectures, the design of the actuation system needs to be carried out in combination with the supporting structure as they both participate in withstanding the operative
loads. The integrated approaches adopted for the design of the morphing flap structure and embedded actuation have been outlined in this work; the outcomes of each design phase have been presented and critically analyzed.

Proceedings of SPIE Smart Structures and NDE Conference (Digital Forum), 2021

Large efforts are currently being spent in Europe for the maturation of innovative technologies e... more Large efforts are currently being spent in Europe for the maturation of innovative technologies enabling the application of morphing systems on next-generation civil transport aircraft. Running along with the CleanSky2 platform, the AirGreen2 project aims to evolve the proofs of concept addressed during the CleanSky program into true-scale demonstrators for a more comprehensive validation of morphing architectures both on the ground and in flight. In this challenging framework, research activities have been carried out to design a novel multi-modal camber morphing flap for the enhancement of the aerodynamic performances of a new-generation regional aircraft. Referring to CFD analyses, very relevant benefits in terms of CLmax increase and stall angle delay were proved to be achievable by properly morphing the camber of the flap; the extra-lift produced by flap cambering resulted more than adequate to allow for take-off and landing at a single flap deployment angle, in turn much lower than those required by a standard flap in both settings. As a side positive effect, a dramatic simplification of the flap deployment system was shown to be practicable, together with the adoption of fairing-less (no-drag) solutions with flap tracks fully embedded into the wing. In addition, wing aerodynamic efficiency in cruise was demonstrated to be enhanced by locally morphing the tip of the flap still exposed to the aerodynamic flow in flap-retracted configuration. The design and validation of the smart architecture enabling the different morphing modes required for low speed (take-off / landing) and high speed (cruise) conditions, consisted of a complex process involving both wind tunnel and ground tests. To increase the relevance of the wind tunnel test campaign, a large scale-factor (1:3) was selected for the test-article, in combination with the realization of the very same Mach numbers expected in flight. Standing the un-scalability of the flap architecture conceived for ground tests and flight operations, a very challenging design was faced for the test article, in order to define a totally new morphable system (Fig.1), assuring the same functionalities of the true-scale device. The path followed to accomplish this task has been outlined in this work, with emphasis on adopted design philosophy, implemented methodologies, and technological solutions.

Proceedings of SPIE - Smart Structures and NDE Conference (Digital Forum), 2020

Morphing is an increasingly investigated topic in aeronautics due to the performance improvements... more Morphing is an increasingly investigated topic in aeronautics due to the performance improvements brought by aerodynamic shapes adaptivity on large aircraft. Being aerodynamics mainly driven by geometry, a structure that can modify its shape may achieve tremendous capability enhancement, especially if its operating scenario is wide. However, the implementation of morphing structures leads to many issues that still need to be properly solved to make the technology fully operative in real application scenarios. For instance, additional DOFs generate systems with increased modal density and then with more complex aeroelastic behaviour, and premature onset of dynamic instabilities. The authors of the present paper have dealt with this problem in other publications, in cooperation with several colleagues, and interesting results are available in literature, to some extent. In this general framework, there are peculiar aspects that only recently have started to catch the attention of the scientific community. Among those, a particular one is the objective of the present work, referring to the numerical simulation strategy of adaptive devices. The kinematic system at the basis of a wide class of morphing structures is driven by an actuation chain, which gives an important contribution to the already cited aeroelastic behaviour. For safety-critical embedded subsystems, it is crucial to detect potential failures and predict their impacts since the early design stages. Now, kinematic components significantly affecting the structural dynamics, as torsion bars and bearings, are assumed rigid in the traditional simulation strategy. If such a concept may be supposed valid for standard layouts (as in the case of flap, ailerons and other moveable systems), it cannot be held for architectures integrating hundreds of those mechanical parts. This work addresses preliminary investigations on systematic analyses carried out on detailed simulations of selected components of aircraft morphing structures, trying to evaluate the effects of elasticity of bearings and hinged connections on the global dynamic response.

Proceedings of SPIE - Smart Structures and NDE Conference (Denver - CO, USA), 2019

After pioneering examples in the ’70 and the ’80, technology advances have brought aircraft morph... more After pioneering examples in the ’70 and the ’80, technology advances have brought aircraft morphing systems close to the exploitation on commercial vehicles. However, in spite of many successes, further steps shall be accomplished before series production lines are entered. They introduce new needs and sometimes exasperate aspects till now under control in the design phase. The increased number and kind of parts pushes for implementing additive manufacturing techniques; their modelling gives rise in turn to important simulation challenges. In case of mechanical, alternative to compliant systems, modelling of elements shall take in consideration behavior that is substantially different from the analogous counterparts on classical devices. Hinges and torsion bars are more diffused and smaller in these architectures. This work
deals with hinges modelling inside mechanically-driven architectures for adaptive winglets. Impact of these aerodynamic surfaces on aircraft stability is crucial and accurate models are required to guarantee their correct implementation.
Morphing capability emphasizes this occurrence even more. Schematization effects are investigated in terms of both static and dynamic response. The variation of the deformed shape is therefore examined, identifying the strain map and internal
forces distribution changes, essential for design purposes and stress analysis. Modal characteristics deviations are then explored, which may substantially influence aeroelastic stability margins. It is envisaged that this approach could be exploited to consider lags effect. A parametric investigation is finally carried out to identify structural behavior sensitivity to such kind of modifications.

Proceedings of SPIE - Smart Structures and NDE Conference (Denver - CO, USA), 2019

The adoption of mechanical systems represents a very promising solution to realistically enable w... more The adoption of mechanical systems represents a very promising solution to realistically enable wing-camber morphing for large civil aircraft. These systems implement the change of shape through the relative motion of parts usually interconnected by means of hinges, and therefore, without any morphing-induced elastic deformation of the load carrying structure; conversely to what happens in compliant structures, the energy provided by the actuation system is here spent to counteract only the external aerodynamic loads which are in turn dependant on shape, speed and flight altitude. Apart of the more effective use of the available power, the mechanical systems show a higher level of technological maturity and readiness for flight thanks to their
higher robustness, reliability and maintainability, as well as in force of their similarity with conventional airworthy architectures already in flight. On the other hand, the use of multiple-hinges connections imposes a
careful analysis of the effects induced by any degradation of their mechanical performance leading to overall system malfunction or local failures. In the framework of the CleanSky2, a research program in aeronautics among the largest ever founded by the European Union, the authors focused on the design and validation of a camber-morphing flap specifically tailored for EASA CS-25 category aircraft. The shape transition is obtained through a smart architecture based on segmented (finger-like) ribs with embedded electromechanical actuators. Three large tabs were located at the flap trailing edge to actively control the
shape of the wing in cruise and to optimize the aerodynamic load distribution along the span. Aeroelastic phenomena related to these flap components were duly addressed since the very preliminary design stage in order to avoid the maturation of a potentially unstable architecture; rational approaches compliant with applicable airworthiness requirements were implemented to properly model and investigate the aeroelastic behaviour of the flap tabs in nominal working conditions. Finally, free plays and internal failures were accurately simulated and their effects on the aeroelastic stability of the aircraft were duly investigated in order to assess the robustness of the conceived tabs as well as of the embedded mechanical subsystems
driving their motion.

Proceedings of ASME 2018 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, SMASIS 2018 (San Antonio - TX, USA - September 10,12) , 2018

In the framework of Clean Sky 2 Airgreen 2 (REG-IADP) European research project, a novel multifun... more In the framework of Clean Sky 2 Airgreen 2 (REG-IADP) European research project, a novel multifunctional morphing flap technology was investigated to improve the aerodynamic performances of the next Turboprop regional aircraft (90 passengers) along its flight mission. The proposed true-scale device (5 meters span with a mean chord of 0.6 meters) is conceived to replace and enhance conventional Fowler flap with new functionalities. Three different functions were enabled: overall airfoil camber morphing up to +30° (mode 1), +10°/-10° (upwards/downwards) deflections of the flap tip segment (mode 2), flap tip “segmented” twist of ±5° along the outer flap span (mode 3). Morphing mode 1 is supposed to be activated during take-off and landing only to enhance aircraft high-lift performances and steeper initial climb and descent. Thanks to this function, more airfoil shapes are available at each flap setting and therefore a dramatic simplification of the flap deployment system may be implemented. Morphing modes 2 and 3 are enabled in cruise and off-design flight conditions to improve wing aerodynamic efficiency.

The novel structural concept of the three-modal morphing Fowler flap (3MMF) was designed according to the challenges posed by real wing installation issues. The proposed concept consists of a multi-box arrangement activated by segmented ribs with embedded inner mechanisms to realize the transition from the baseline configuration to different target aero-shapes while withstanding the aerodynamic loads. Lightweight and compact actuating leverages driven by electromechanical motors were properly synthesized to comply with stringent requirements for real aircraft implementation: minimum actuating torque, minimum number of motors, reduced weight, and available design space. The methodology for the kinematic design of the inner mechanisms is based on a building block approach where the instant center analysis tool is used to preliminary select the locations of the hinges’ leverages. The final geometry of the inner mechanisms is optimized to maximize the mechanical advantage as well as to provide the kinematic performances required by the three different morphing modes. The load-path was evaluated, and the cross-sectional size of leverages was subsequently optimized. Finally, actuating torques predicted by instant center analysis were compared to the calculated values from finite element analysis. The structural sizing process of the multi-box arrangement was carried out considering elementary methods, and results were compared with finite element simulations.

Proceedings of ASME 2018 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, SMASIS 2018 (San Antonio - TX, USA - September 10,12), 2018

Future aircraft wing technology is rapidly moving toward flexible and morphing wing concepts capa... more Future aircraft wing technology is rapidly moving toward flexible and morphing wing concepts capable to enhance aircraft wing performance in off-design conditions and to reduce operative maneuver and gust loads. However, due to the reduced stiffness, increased mass, and increased degree of freedom (DOF), such mechanical systems require advanced aeroelastic assessments since the early design phases; this appears crucial to properly drive the design of the underlying mechanisms since the conceptual phase by mitigating their impact on the whole aircraft aeroelastic stability. Preliminary investigations have shown that the combined use of adaptive flap tabs and morphing winglets significantly improves aircraft aerodynamic performance in climb and cruise conditions by the order of 6%. Additionally, by adapting span-wise lift distributions to reduce gust solicitations and alleviate wing root bending moment at critical flight conditions, significant weight savings can also be achieved. Within the scope of Clean Sky 2 Airgreen 2 project, flutter and divergence characteristics of a morphing wing design integrating adaptive winglets and flap tabs are discussed. Multi-parametric flutter analyses are carried out in compliance with CS-25 airworthiness requirements (paragraph 25.629, parts (a), (b), (c) and (d)) to investigate static and dynamic aeroelastic stability behavior of the aircraft. The proposed kinematic systems are characterized by movable surfaces, each with its own domain authority, sustained by a structural skeleton and completely integrated with EMA-based actuation systems. For that purpose, a sensitivity analysis was performed taking into account variations of the stiffness and inertial properties of the referred architectures. Such layouts were reduced to a stick-equivalent model which properties were evaluated through MSC-NASTRAN-based computations. The proprietary code SANDY 4.0 was used to generate the aero-structural model and to solve the aeroelastic stability equations by means of theoretical modes association in frequency domain. Analyses showed the presence of critical modal coupling mechanisms in nominal operative conditions as well as in case of system malfunctioning or failure. Design solutions to assure clearance from instabilities were then investigated. Trade-off flutter and divergence analyses were finally carried out to assess the robustness of the morphing architectures in terms of movable parts layout, mass balancing and actuators damping.

Proceedings of ASME 2018 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, SMASIS 2018 (San Antonio - TX, USA - September 10,12), 2018

Regional aviation is an innovation driven sector of paramount importance for the European Union e... more Regional aviation is an innovation driven sector of paramount importance for the European Union economy. Large resources and efforts are currently spent through the CleanSky program for the development of an efficient air transport system characterized by a lower environmental impact and unequalled capabilities of ensuring safe and seamless mobility while complying with very demanding technological requirements. The Green Regional Aircraft (GRA) panel, active from 2006, aims to mature, validate and demonstrate green aeronautical technologies best fitting the regional aircraft that will fly from 2020 onwards with reference to specific and challenging domains: from advanced low-weight and high performance structures up to all-electric systems and bleed-less engine architectures, from low noise/high efficiency aerodynamic up to environmentally optimized missions and trajectories management. The development of such technologies addresses two different aircraft concepts, identified by two seat classes, 90-pax with Turboprop (TP) engine and 130-pax, in combination with advanced propulsion solutions, namely, the Geared Turbofan (GTF), the Advanced Turbofan (ATF) and the Open Rotor (OR) configuration. Within the framework of the Clean Sky program, and along nearly 10 years of research, the design and technological demonstration of a novel wing flap architecture was addressed. Research activities aimed at demonstrating the industrial feasibility of a morphing architecture enabling flap camber variation in compliance with the demanding safety requirements applicable to the next generation GRA in both open rotor and turboprop configurations. The driving motivation was found in the opportunity to replace a conventional double slotted flap with a single slotted morphing flap assuring improved high lift performances -in terms of maximum attainable lift coefficient and stall angle- while lowering emitted noise, fuel-burnt and deployment system complexity. Additional functionalities for load control and alleviation were then considered and enabled by a smart architecture allowing for an independent shape-control of the flap tip region during cruise. The entire process moving from concept definition up to the experimental qualification of true scale prototypes, characterized by global and multi-zone differential morphing capabilities, is here described with specific emphasis on the adopted design philosophy and implemented technological solutions. Paths to improvements are finally outlined in perspective of a low-term item certification and series production.

Proceedings of ASME 2018 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, SMASIS 2018 (San Antonio - TX, USA - September 10,12), 2018

Researchers and engineers design modern aircraft wings to reach high levels of efficiency with th... more Researchers and engineers design modern aircraft wings to reach high levels of efficiency with the main outcome of weight saving and airplane lift-to-drag ratio increasing. Future commercial aircraft need to be mission-adaptive to improve their operational efficiency. Twistable trailing edge could be used to improve aircraft performances during climb and off-design cruise conditions in response to variations in speed, altitude, air temperature, and other flight parameters. Indeed, “continuous” span-wise twist of the wing trailing edge could provide significant reduction of the wing root bending moment through redistribution of the aerodynamic load leading to an increase of the payload/structural weight ratio. Within the framework of the Clean Sky 2 (CS2) European research project, the authors focused on the preliminary design of a full-scale composite multifunctional tab retrofitting the outboard morphing Fowler flap of a turboprop regional aircraft. The investigation domain of the novel device is equal to 5.15 meters in span-wise direction and 10% of the local wing chord. The structural and kinematic design process of the actuation system is completely addressed: two rotary electromechanical motors, placed in the root and tip flap sections, are required to activate the inner mechanisms enabling delta twist angles up to 10 degrees along the outboard region when the flap is stowed in the wing. The structural layout of the thin-walled closed-section composite tab represents a promising concept to balance the conflicting requirements between load-carrying capability and shape adaptivity in morphing lightweight structures. The main design parameters are optimized to minimize actuation torque required for twisting while providing proper flexural rigidity to withstand limit aerodynamic pressure distributions for large airplanes. Finally, the embedded system functionality of the actuation system coupled with the composite wing trailing edge is fully investigated by means of detailed finite element simulations. Results of actuation system performances, and aeroelastic deformations considering operative aerodynamic loads demonstrate the potential of the proposed structural concept to be energy efficient, and lightweight for real aircraft implementation.

Proceedings of ASME 2018 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, SMASIS 2018 (San Antonio - TX, USA - September 10,12), 2018

By introducing the progresses on Morphing currently achieved within the European Project “AIRGREE... more By introducing the progresses on Morphing currently achieved within the European Project “AIRGREEN2”, in Clean-Sky 2 GRA platform, this work presents a review of the research step forwards accomplished in the last decade by three Italian Partners largely active in the field: the Italian Aerospace Research Centre, the University of Naples “Federico II” and the Politecnico of Milano. A chronologic overview is at first presented, revisiting the research programs and the achieved results; an organic development path has been then built, starting from low TRL achievements up to arrive at the most complete technical accomplishments, characterized by a high level of integration and targeting specific aerospace applications.

Proceedings of SPIE - Smart Structures and NDE Conference (Denver - CO, USA) , 2018

The in-flight control of the wing shape is widely considered as one of the most promising solutio... more The in-flight control of the wing shape is widely considered as one of the most promising solutions to enhance the aerodynamic efficiency of the aircraft thus minimizing the fuel burnt per mission ([1]-[26]). In force of the fallout that the implementation of such a technology might have on the greening of the next generation air transport, ever increasing efforts are spent worldwide to investigate on robust solutions actually compliant with industrial standards and applicable airworthiness requirements. In the framework of the CleanSky2, a research program in aeronautics among the largest ever founded by the European Union, the authors focused on the design and validation of two devices enabling the camber-morphing of winglets and flaps specifically tailored for EASA CS-25 category aircraft ([29]). The shape transition was obtained through smart architectures based on segmented (finger-like) ribs with embedded electromechanical actuators. The combined actions of the two smart systems was conceived to modulate the load distribution along the wing while keeping it optimal at all flight conditions with unequalled benefits in terms of lift-over-drag ratio increase and root bending moment alleviation. Although characterized by a quasi-static actuation, and not used as primary control surfaces, the devices were deeply analysed with reference to their impact on aircraft aeroelastic stability. Rational approaches were adopted to duly capture their dynamics through a relevant number of elastic modes; aeroelastic coupling mechanisms were identified in nominal operative conditions as well as in case of systems' malfunctioning or failure. Trade off flutter and divergence analyses were finally carried out to assess the robustness of the adopted solutions in terms of movable parts layout, massbalancing and actuators damping. © 2018 SPIE.

Proceedings of SPIE - Smart Structures and NDE Conference (Denver - CO, USA), 2018

A morphing structure can be considered as the result of the synergic integration of three main sy... more A morphing structure can be considered as the result of the synergic integration of three main systems: the structural system, based on reliable kinematic mechanisms or on compliant elements enabling the shape modification, the actuation and control systems, characterized by embedded electromechanical actuators and robust control strategies, and the sensing system, usually involving a network of sensors distributed along the structure to monitor its state parameters. Technologies with ever increasing maturity level are adopted to assure the consolidation of products in line with the aeronautical industry standards and fully compliant with the applicable airworthiness requirements. In the framework of the CleanSky2, one of the largest research projects ever funded by the European Union, a novel multi-modal camber morphing flap was conceived for the enhancement of the aerodynamic performances of the next generation green regional aircraft. Thanks to different morphing modes, the shape of the flap can be suitably adapted in order to preserve an optimal configuration as the aircraft trim parameters change according to the specific flight phase (take-off, climb, cruise, descent, landing). To further improve the benefits brought by such technology on the wing aerodynamic efficiency, an active flow control system based on plasma synthetic jet (PSJ) actuators was investigated for a potential installation on the upper skin of the flap. PSJ actuators, or Sparkjets, are able to produce very high jet velocities, without the aid of any moving parts, affecting the structure of the flow-field to be controlled and allowing a positive variation of the aerodynamic forces on the aircraft, with a modest power consumption. This work is focused on the two main aspects related to the feasibility of PSJ actuators integration into the adaptive flap skin: the thermal and electromagnetic interferences of the actuators with the other electronic equipment of the flap. Experimental measurements were carried out to characterize the thermal and the electromagnetic fields induced by the operating device into the surrounding structure. A simplified test article was designed and manufactured to support all experimental activities while being fairly representative of the actual PSJ-skin assembly. Test results allowed for a definition of the safety-critical areas for the installation of flap actuation, control and sensing systems. © 2018 SPIE.

Proceedings of SPIE - Smart Structures and NDE Conference (Denver - CO, USA), 2018

The design and application of adaptive devices are currently ambitious targets in the field of av... more The design and application of adaptive devices are currently ambitious targets in the field of aviation research addressed at new generation aircraft. The development of intelligent structures involves aspects of multidisciplinary nature: the combination of compact architectures, embedded electrical systems and smart materials, allows for developing a highly innovative device. The paper aims to present the control system design of an innovative morphing flap tailored for the next generation regional aircraft, within Clean Sky 2 - Airgreen 2 European Research Scenario. A distributed system of electromechanical actuators (EMAs) has been sized to enable up to three operating modes of a structure arranged in four blocks along the chord-wise direction: •overall camber-morphing; •upwards/downwards deflection and twisting of the final tip segment. A state-of-art feedback logic based on a decentralized control strategy for shape control is outlined, including the results of dynamic stability analysis based on the blocks rational schematization within Matlab/Simulink® environment. Such study has been performed implementing a state-space model, considering also design parameters as the torsional stiffness and damping of the actuation chain. The design process is flowing towards an increasingly "robotized" system, which can be externally controlled to perform certain operations. Future developments will be the control laws implementation as well as the functionality test on a real flap prototype. © 2018 SPIE.

Proceedings of SPIE - Smart Structures and NDE Conference (Denver - CO, USA), 2018

Variation of trailing edge camber proved to be one of the easiest and most effective ways to modi... more Variation of trailing edge camber proved to be one of the easiest and most effective ways to modify aerofoil shape to match different aircraft operational weights, with benefits approaching 3% of fuel savings or, equivalently, range extension. This is particularly the case of commercial planes, where both initial take-off conditions (because of the unpredictable payload or the specific required mission-transfer flight, for instance) and in-flight states (for the kerosene consumption) can undergo significant differences. Several studies (like the European Research Programs SARISTU or JTI-GRA) demonstrated that the most sensible region for installing an adaptive trailing edge system for those aims is towards the wing tip. This is unfortunately a very delicate area where usually ailerons are deployed and where significant mass insertions could affect the aeroelastic response with some risks of instabilities. Furthermore, the volume available are really limited so that the installation of a fully embedded system is challenging. Moving from the experience taken in many former projects as the cited ones, the authors faced the problem of installing a fully integrated adaptive trailing edge system within the existing structural skeleton of a reference aileron and defined a design strategy to take into account the aeroelastic modifications due to the installation of such a device. Besides, the architecture preserved the original function of that control surface so that it could work as a standard aileron (classical rigid tab movement) with the augmented function of a deformable, quasi-static shape. In this sense, the proposed system exhibited a double functionality: A conventional rigid aileron with augmented shape modification capability plus a continuous, slow change of the trailing edge, occurring during flight for compensating aircraft weight variation. The research was carried out within the Italian-Canadian program MDO-505 and led to the realisation of a multifunctional aileron with two operational motor systems (one for the classical aileron working and the other for the morphing enforcement), completely integrated so that no external element was visible or affected the aerodynamics of the wing. The manufacture of this device was possible thanks to the development of a suitable design process that allowed taking into account both the structural and the aeroelastic response of the integrated architecture. This system was part of an adaptive wing section that was completed with the realisations made by the ETS of Montreal, the Quebecoise Consortium for Aerospace Research and Innovation (CRIAQ) and the IAR-NRC, supported by Bombardier and Thales Canada. The joint demonstrator was tested in the wind tunnel at the NRC facilities in Ottawa and gave confirmation of the aerodynamic, aeroelastic and structural predictions. The paper that is herein presented deals therefore with the design process and the manufacture of an adaptive trailing edge, installed within the existing aileron system of a wing segment, to undergo wind tunnel tests. The resulting device considers the definition of the kinematic structural system, the development of the integrated actuator system, their integration and the assessment of their static and dynamic structural response, and the verification of a safe aeroelastic behavior. Numerical and experimental results are presented, achieved in lab and wind tunnel environments. © 2018 SPIE.

Proceedings of the ASME 2017 Conference on Smart Materials, Adaptive Structures and Intelligent Systems, SMASIS (Snowbird - UT, USA), 2017

Airfoil camber adaptation may be the key for the performance improvement of wings for many specif... more Airfoil camber adaptation may be the key for the performance improvement of wings for many specific applications, including shorter take-off distance, compensation of weight variation and so on. Following the successful experiences gained in SARISTU, where an adaptive trailing edge device was developed for medium to large size commercial aircraft, the authors propose to exploit the developed architecture to a small aircraft wing. The basic reasons behind that mainly rely on the associated possibility to access easier implementation onto a real aircraft instead of referring to wing segments for wind tunnel or ground tests. In this way, many operative problems are faced, that would be otherwise neglected in usual lab experimentation. First of all, the integration of the proposed device onto a flying machine, that in turn pose the problem of facing the interface with the existing systems. Secondly, the necessity of including the device into the flap while fully preserving its current functionality. Furthermore, the necessity of developing a robust design process that allows having the release of the permit-to-fly. Each of the above steps, nonexhaustive in illustrating the difficulty of the addressed challenge, is structured in many other sub-segments, ranging from a suitable FHA analysis to a full re-design of the existing high lift systems or the adaptation of the architecture of the reference morphing trailing edge itself. This last item poses the classical challenge of the scaling issues, requiring the structural and the actuation subsystems to entirely fit into the new geometry. The objective of the present research is then to verify the feasibility of applying a certain architectural morphing philosophy onto a real aircraft, taking into account all the operational difficulties related to such an operation. This paper reports the activities related to the exploitation of the reference adaptive structural architecture, to the geometry of a flap of a small aircraft. In detail, the system layout is presented, followed by a FE analysis of the structural system under the operational loads and an estimation of the weight penalty associated to this transformation. Interfaces of the flap system with the main aircraft body are considered as constraints to the design development, so that the only flap is affected. © 2017 ASME.

Proceedings of the 8th International Conference on Mechanical and Aerospace Engineering, ICMAE (Prague, CZ), 2017

The common challenge of all aerospace advancements is greening the air transport. This led the re... more The common challenge of all aerospace advancements is greening the air transport. This led the recent research programs towards the study of 'metamorphic' wing structures, capable of adapting their geometry to the different conditions of flight. The development of morphing structures allows the reduction of drag and the increase of range, together with the growth of load control effectiveness. In this context, the European research project SARISTU addressed the physical integration of smart and morphing structural concepts, by implementing them on a true scale outer wing belonging to a CS-25 category aircraft finally tested in a large Wind Tunnel. In the framework of SARISTU project, the design of an Adaptive Trailing Edge Device was developed. The morphing skin concept consisted of a segmented skin, with aluminum and silicone foam strips covered by a protective silicone top-layer. A two-bay demonstrator was tested inside the Wind Tunnel at the Department of Industrial Engineering of the University of Naples 'Federico II'; experimental analyses were performed in order to verify whether the silicone parts could show out of plane bumps induced by the aerodynamic loads occurring during the Wind Tunnel test campaign. A photogrammetric optic approach was adopted, in order to reach the aforementioned targets in a non-invasive way; such methodology was selected due the high resolution assured at a very low implementation costs. Obtained results allowed to confirm the demonstrator well done design and opened the doors to the next experimental test campaign performed in TsAGI Russian Wind Tunnel, on the outer wing equipped with a five-bay demonstrator of the Adaptive Trailing Edge Device. © 2017 IEEE.

AIP Conference Proceedings (from ICEESM 2017, Lyon, France), 2017

Nowadays, the design choices of the new generation aircraft are moving towards the research and d... more Nowadays, the design choices of the new generation aircraft are moving towards the research and development of innovative technologies, aimed at improving performance as well as to minimize the environmental impact. In the current "greening" context, the morphing structures represent a very attractive answer to such requirements: both aerodynamic and structural advantages are ensured in several flight conditions, safeguarding the fuel consumption at the same time. An aeronautical intelligent system is therefore the outcome of combining complex smart materials and structures, assuring the best functionality level in the flight envelope. The Adaptive Trailing Edge Device (ATED) is a sub-project inside SARISTU (Smart Intelligent Aircraft Structures), an L2 level project of the 7th EU Framework programme coordinated by Airbus, aimed at developing technologies for realizing a morphing wing extremity addressed to improve the general aircraft performance and to reduce the fuel burning up to 5%. This specific study, divided into design, manufacturing and testing phases, involved universities, research centers and leading industries of the European consortium. The paper deals with the aeroelastic impact assessment of a full-scale morphing wing trailing edge on a Large Aeroplanes category aircraft. The FE (Finite Element) model of the technology demonstrator, located in the aileron region and manufactured within the project, was referenced to for the extrapolation of the structural properties of the whole adaptive trailing edge device placed in its actual location in the outer wing. The input FE models were processed within MSC-Nastran® environment to estimate stiffness and inertial distributions suitable to construct the aeroelastic stick-beam mock-up of the reference structure. Afterwards, a flutter analysis in simulated operative condition, have been carried out by means of Sandy®, an in-house code, according to meet the safety requirements imposed by the applicable aviation regulations (paragraph 25.629, parts (a) and (b)-(1)). © 2017 Author(s).

Proceedings of SPIE - Smart Structures and NDE Conference (Portland - OG, USA), 2016

Within the framework of the JTI-Clean Sky (CS) project, and during the first phase of the Low Noi... more Within the framework of the JTI-Clean Sky (CS) project, and during the first phase of the Low Noise Configuration Domain of the Green Regional Aircraft - Integrated Technological Demonstration (GRA-ITD, the preliminary design and technological demonstration of a novel wing flap architecture were addressed. Research activities were carried out to substantiate the feasibility of morphing concepts enabling flap camber variation in compliance with the demanding safety requirements applicable to the next generation green regional aircraft, 130- seats with open rotor configuration. The driving motivation for the investigation on such a technology was found in the opportunity to replace a conventional double slotted flap with a single slotted camber-morphing flap assuring similar high lift performances -in terms of maximum attainable lift coefficient and stall angle- while lowering emitted noise and system complexity. Studies and tests were limited to a portion of the flap element obtained by slicing the actual flap geometry with two cutting planes distant 0.8 meters along the wing span. Further activities were then addressed in order to increase the TRL of the validated architecture within the second phase of the CS-GRA. Relying upon the already assessed concept, an innovative and more advanced flap device was designed in order to enable two different morphing modes on the basis of the A/C flight condition / flap setting: Mode1, Overall camber morphing to enhance high-lift performances during take-off and landing (flap deployed); Mode2, Tab-like morphing mode. Upwards and downwards deflection of the flap tip during cruise (flap stowed) for load control at high speed. A true-scale segment of the outer wing flap (4 meters span with a mean chord of 0.9 meters) was selected as investigation domain for the new architecture in order to duly face the challenges posed by real wing installation. Advanced and innovative solutions for the adaptive structure, actuation and control systems were duly analyzed and experimentally validated thus proving the overall device compliance with industrial standards and applicable airworthiness requirements. © 2017 SPIE.

Shape Memory Alloy Engineering: For Aerospace, Structural and Biomedical Applications - 2nd Edition (Elsevier), 2021

With increased emphasis on adaptability and multifunctionality, smart materials are increasingly ... more With increased emphasis on adaptability and multifunctionality, smart materials are increasingly becoming a focus of interest for aircraft applications. A number of international workshops on smart materials, such as SPIE and ASME, take place every year, and many articles can be found in the literature dealing with shape memory alloy (SMA)-based applications. p0015 The use of SMAs gives the chance to design mechanical and aerospace structures for better system performance, such as low vibration, shape control, and structural health monitoring. Such technologies, rapidly transitioning from basic research to innovative applications with an increasing profile of maturity, offer the possibility of enhancing current structural functionalities or replacing existing ones in retrofit applications. p0020 Although SMA alloys can be used and are doing so in many industrial sectors, novel applications continue to be developed because of their unique thermomechanical characteristics. In the early growth of SMA technology, the medical field was probably the most active, followed by the military sector with fasteners and couplings. More than 100,000 SMA fittings have been installed (for instance, in aircraft such as the F-14) and there have been no reported failures [1,2]. p0025 With the broader availability of alloys and the constant maturation of the related technology , a wider spectrum of other applications emerged. To date, most SMA-based technologies serve the needs of the biomedical, medicine, and orthodontics industries with stents, guide wires, graft reinforcement, orthodontics, surgical staples, and blood clot filters , owing to their excellent biocompatibility. Other areas such as eyeglass frames, cellular phone antennas, and automotive devices are growing rapidly. SMA torsional springs and linear motion actuators are valid alternatives to electrical motors because of the inherent potential to achieve mass and volume savings, which cannot be realized by traditional actuators [3]. p0030 There are various advantages to using smart materials such as SMAs in aeronautical applications. Different solutions and technologies have been developed and proposed, responding to aeronautical technological needs. In this section, some of the most interesting SMA applications in aeronautics are briefly reviewed.

Smart Intelligent Aircraft Structures - SARISTU (Springer), 2016

See the attached file.

Smart Intelligent Aircraft Structures - SARISTU (Springer), 2016

See the attached file.

Smart Intelligent Aircraft Structures - SARISTU (Springer), 2016

See the attached file.

Morphing Wing Technologies: Large Commercial Aircraft and Civil Helicopters (Elsevier), 2017

A major difficulty in the design of morphing devices for aircraft wings is to reach an adequate c... more A major difficulty in the design of morphing devices for aircraft wings is to reach an adequate compromise between high load-carrying capacity to withstand aerodynamic loads and sufficient flexibility to achieve better aerodynamic performance. Such counteracting and demanding targets lead to an increased structural complexity whose experimental characterization is a matter of high priority prior to the ultimate physical integration into the aircraft structure. Compared to the passive counterpart, morphing devices enable augmented capabilities by locally adapting wing shape and lift distribution through either a quasistatic or dynamic deflection, with excursions ranging into a few units of degrees, positive and negative.This chapter provides an overview of the verification approaches suitable for morphing devices ranging from the basic concepts applicable to individual subsystems up to the global experimental analysis of the integrated system. A number of test objectives are illustrated at both component and system level, providing practical tips for the experimental analysis of morphing structures combining both compliant structural systems and multibox self-contained actuation mechanisms. © 2018 Elsevier Ltd. All rights reserved.

Morphing Wing Technologies: Large Commercial Aircraft and Civil Helicopters (Elsevier), 2017

More severe regulations are growing worldwide due to increasing air traffic in order to reduce fu... more More severe regulations are growing worldwide due to increasing air traffic in order to reduce fuel consumption and noise. The achievement of challenging targets in terms of pollutant emissions abatement demands for the development of innovative aircraft technologies. Morphing is one of them and plays an extraordinary role for the improvement of aircraft performance. Many research projects are currently focused on morphing both in US and Europe. Among these, the CRIAQ-MDO505 constitute the first trans-European cooperation project on smart technologies. Its aim is to investigate morphing structures potential through the design and manufacturing of a full-scale variable camber aileron designed according to the requirements of a regional aircraft. This project was carried out by Italian and Canadian academies, research centers, and leading industries. In this framework, the authors worked on the development of this technology addressing both numerical and experimental activities up to a thorough validation of a physical prototype. The effective capabilities of the adaptive prototype were proven by means of wind tunnel and ground test campaigns which successfully demonstrated the feasibility and the reliability of a morphing aileron. © 2018 Elsevier Ltd. All rights reserved.

Morphing Wing Technologies: Large Commercial Aircraft and Civil Helicopters (Elsevier), 2017

Aircraft wings are usually optimized for a specific design point. However, since they operate in ... more Aircraft wings are usually optimized for a specific design point. However, since they operate in a wide variety of flight regimes, some of these have conflicting impacts on aircraft design, as an aerodynamically efficient configuration in one instance may perform poorly in others.Conventional wing structures preclude any significant adaptation to changing conditions; movable surfaces, such as flaps or slats, lead to limited changes of the overall shape with narrow benefits compared with those that could be obtained from a wing structure that is inherently deformable and adaptable.An adaptive trailing edge concept conceived to enhance wing aerodynamic performance in cruise condition is outlined. The camber of the trailing edge is controlled during flight to compensate the weight reduction following the fuel burning. In this way, the trimmed configuration remains optimal in terms of efficiency (lift to drag ratio) or minimal drag with positive fallouts on aircraft fuel consumption per flight.The main steps concerning the design of the device are reported, with a special focus on each of its relevant architectural elements. In detail, the skin, the structural skeleton, the actuator, sensor, and control systems are dealt with. Some attention is devoted to aspects that are necessary to come to a finalized product of industrial relevance: namely, the aeroelastic and the safety analyses. The former assumes a main relevance because the system has augmented degrees of freedom with respect to a standard layout and then, a more complex dynamic response and a higher risk of instability. The latter is necessary to envisage a future certification process of this kind of device that requires the development of a dedicated path. © 2018 Elsevier Ltd. All rights reserved.

Morphing Wing Technologies: Large Commercial Aircraft and Civil Helicopters (Elsevier), 2017

Morphing structures have the greatest potential to dramatically improve aircraft aerodynamic perf... more Morphing structures have the greatest potential to dramatically improve aircraft aerodynamic performance. They are designed to accomplish with a single device what conventional mechanisms can do with major aerodynamic penalties. In doing so, such systems have to be flexible enough to deliver the desired motion while ensuring a certain structural response under operative loads.In this chapter, focus is given to the structural design of morphing structures. The objective is to develop a generalized scheme, spanning from stress analysis to material selection, to design morphing devices that can morph one shape to another with minimum error. After a brief introduction, general design guidelines and practical tips are provided to ensure satisfactory mechanical structural performance and durability, with an overview of subcomponents and systems validation, design loads and simulation constraints. The application of this approach is demonstrated through an adaptive trailing edge device design example, including FE modeling, simulations and results assessment. © 2018 Elsevier Ltd. All rights reserved.

Morphing Wing Technologies: Large Commercial Aircraft and Civil Helicopters (Elsevier), 2017

When dealing with the design of morphing wings, conventional structural arrangements are commonly... more When dealing with the design of morphing wings, conventional structural arrangements are commonly replaced by innovative solutions enabling shape changes through actively controlled elasticity or mechanical systems. In both cases, no simplified rules coming from consolidated experiences may be invoked to guarantee that a specific design will be characterized by stable and sustainable aeroelastic response to external loads expected in service.A rational approach for the aeroelastic analysis of the structural arrangements is therefore recommended since the earliest design stage so that the maturation of unflyable solutions is naturally avoided.The extra-modes method is herein detailed as a dramatically efficient tool to accomplish this paramount task. The morphing device is treated as a substructure and the aircraft (A/C) as the basic system on which the device is installed. Substructure's contribute to the aeroelastic response of the global system is expressed in terms of generalized parameters pertinent to additional and strategically defined modes capturing the substructure dynamics. After recalling the general formulation of the method, two case studies are presented in order to show its great potential to rapidly appreciate the aeroelastic behavior of a given design, irrespective of the maturity level of the design itself. © 2018 Elsevier Ltd. All rights reserved.

Morphing Wing Technologies: Large Commercial Aircraft and Civil Helicopters (Elsevier), 2017

Morphing of metallic wing structures has fascinated generations of researchers; numerous and some... more Morphing of metallic wing structures has fascinated generations of researchers; numerous and sometimes bizarre architectures have been proposed, tailored to specific end-applications and aircraft type. Although different for layout, all of them can be categorized in two basic groups: mechanized architectures and compliant mechanisms.Mechanized architectures implement morphing through the rigid-body motion of stiff subcomponents interconnected by suitably designed kinematic chains and actuation leverages.Each subcomponent of the kinematic chain is sized to provide its own contribution to the adsorption of the external solicitations arising in operative conditions; actuators and actuation transmission line are sized to enable the motion of the system and to preserve given shape configurations while counteracting aerodynamic loads with the minimum need of power.Compliant mechanisms involve the deformation of structural elements to enable the required shape-change; mechanical properties of the structure have to be properly distributed in order to assure adequate morphing compliance and adequate stiffness to withstand external loads.In this chapter, the design philosophy behind each type of morphing structure has been presented, together with practical applications to wing trailing edge camber adaptation.By referring to similar end-application, the adopted design strategies and obtained outcomes are compared, thus better highlighting the advantages and weak points of each morphing solution. © 2018 Elsevier Ltd. All rights reserved.

Computational Methods in Applied Sciences (Springer), 2017

Shape control of adaptive wings has the potential to improve wing aerodynamic performance in off-... more Shape control of adaptive wings has the potential to improve wing aerodynamic performance in off-design conditions. A possible way to attain this objective is to implement specific technologies for trailing edge morphing, aimed at changing the airfoil camber. In the framework of SARISTU project (EU-FP7), an innovative structural system incorporating a gapless deformable trailing edge was developed. A related key technology is the capability to emulate and maintain pre-selected target wing shapes within an established margin, enabling optimal aerodynamic performance under current operational pressure loads. In this paper, the actuation and control logics aimed at preserving prescribed geometries of an adaptive trailing edge under variable conditions are numerically and experimentally detailed. The actuation concept relies on a quick-return mechanism, driven by load-bearing actuators acting on morphing ribs, directly and individually. The adopted unshafted distributed electromechanical system arrangement uses servo-rotary actuators, each rated for the torque of a single adaptive rib of the morphing structure. The adopted layout ensures compactness and weight limitations , essential to produce a clean aerodynamic system. A Fiber Bragg Grating (FBG)-based distributed sensor system generates the information for appropriate open-and closed-loop control actions and, at the same time, monitors possible failures in the actuation mechanism.

Recent Progress in Some Aircraft Technologies (InTech), 2016

European Union is involving increasing amount of resources on research projects that will dramati... more European Union is involving increasing amount of resources on research projects that will dramatically change the costs of building and operating aircraft in the near future. Morphing structures are a key to turn current airplanes to more efficient and versatile means of transport, operating into a wider range of flight conditions. The concept of morphing may aim at a large number of targets, and its assessment strongly depends on the final objectives and the components where it has to be deployed. Maneuver, takeoff, landing, cruise conditions, just to cite few and very general examples, have all their own peculiarities that drive the specifications the wing shape change has to suit on. In general, an adaptive structure ensures a controlled and fully reversible transition from a baseline shape to a set of different configurations, each capable of withstanding the relative external loads. The level of complexity of morphing structures naturally increases as a consequence of the augmented functionality of the reference system. Actuation mechanisms constitute a very crucial aspect for adaptive structures design because has to comply variable wing shapes with associated loads and ensure the prescribed geometrical envelope. This chapter provides a presentation of the state of the art, technical requirements, and future perspectives of morphing ailerons. It addresses morphing aircraft component architecture and design with a specific focus on the structural actuator system integra‐ tion. The approach, including underlying concepts and analytical formulations, combines methodologies and tools required to develop innovative air vehicles. Aileron is a very delicate region, where aeroelastic phenomena may be very important because of the very reduced local stiffness and the complex aerodynamics, typical of the wingtip zone. On the other side, this wing segment showed to be the one where higher cruise benefits could be achieved by local camber variations. This target was achieved while keeping the typical maneuver functions.

Shape Memory Alloy Engineering: For Aerospace, Structural and Biomedical Applications (Elsevier), 2014

The aviation industry has achieved drastic improvements during the past few decades, thanks to re... more The aviation industry has achieved drastic improvements during the past few decades, thanks to research efforts and advances in technology. With increased emphasis on adaptability and multifunctionality, smart materials and adaptive structures are now common terms in the literature and have been investigated extensively in many research programs to explore enhanced capabilities in aeronautical and space applications. The use of smart materials such as shape memory alloys gives us the chance to design mechanical and aerospace structures for better system performance, such as low vibration, shape control, and structural health monitoring. Such technologies, transitioning rapidly from basic research to reliable applications with a certain profile of maturity, offer the possibility of expanding current structural functionalities or replacing existing ones in retrofit applications. © 2015 Elsevier Ltd. All rights reserved.

Morphing Wings Technologies: Large Commercial Aircraft and Civil Helicopters offers a fresh look ... more Morphing Wings Technologies: Large Commercial Aircraft and Civil Helicopters offers a fresh look at current research on morphing aircraft, including industry design, real manufactured prototypes and certification. This is an invaluable reference for students in the aeronautics and aerospace fields who need an introduction to the morphing discipline, as well as senior professionals seeking exposure to morphing potentialities. Practical applications of morphing devices are presented-from the challenge of conceptual design incorporating both structural and aerodynamic studies, to the most promising and potentially flyable solutions aimed at improving the performance of commercial aircraft and UAVs. Morphing aircraft are multi-role aircraft that change their external shape substantially to adapt to a changing mission environment during flight. The book consists of eight sections as well as an appendix which contains both updates on main systems evolution (skin, structure, actuator, sensor, and control systems) and a survey on the most significant achievements of integrated systems for large commercial aircraft. Provides current worldwide status of morphing technologies, the industrial development expectations, and what is already available in terms of flying systems Offers new perspectives on wing structure design and a new approach to general structural design Discusses hot topics such as multifunctional materials and auxetic materials Presents practical applications of morphing devices. © 2018 Elsevier Ltd. All rights reserved.

A wing-flap assembly includes a flap made up of a plurality of flap sections, in which each flap ... more A wing-flap assembly includes a flap made up of a plurality of flap sections, in which each flap section is connected to the preceding one in a rotatable manner, and one or more actuator devices adapted to control the rotation of the flap sections. Each actuator device includes an extended element made of shape memory alloy and an arch-shaped framework made of elastic material, to which the extended element is fixedly connected under tension. Each end of the extended element is fixed to a respective end of the arch-shaped framework. At least one of the actuator devices is connected at one end to the first of the flap sections, and on the other side is adapted to be connected to a wing structure.

The present invention refers to an actuator device and a wing-flap assembly. As it is known, the ... more The present invention refers to an actuator device and a wing-flap assembly. As it is known, the increase in lift required for the take-off and landing phases of an aircraft is mainly obtained through the deflection of a wing-flap around a hinging axis. Such a solution implies the presence of robust control lines and complex actuation devices which significantly contribute to the weight of the whole wing structure. From an aerodynamic point of view, the local modification of the curvature of the wing profile induced by a conventional flap is limited by the excursion range of the flap itself; for this reason only the profile curvatures compatible with the finite number of deflection angles of the mobile surface can be used in operating conditions. The purpose of the present invention is that of providing a wing-flap assembly which allows the weights as well as the operating and maintenance costs to be reduced with respect to conventional wing-flap technology, as well as allowing an optimization of the aerodynamic performances of the lift devices to be obtained. According to the invention the wing-flap is able to dynamically modify its own curvature (morphing flap) according to specific design requirements. The flap is controlled through one or more actuator devices based upon shape memory alloy, which enormously reduces the total weight of the group and makes the control system simpler to manufacture

The development of elastomeric materials for adaptive wings focuses on the elasticity at -55 °C t... more The development of elastomeric materials for adaptive wings focuses on the elasticity at -55 °C to ensure morphing at cruise altitudes. FEM simulations and mechanical tests are carried out to optimize fatigue and aging properties of this new multi-material device. Two large skin panels are manufactured and successfully assembled into a true-scale wind tunnel demonstrator for the experimental validation of adaptive trailing edge device functionality in simulated operative conditions.