bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical and experimental assessment of a linear aerospike
Authors: Resta E.
Published: October 2023

Abstract. In the present work a linear aerospike nozzle model has been studied with cold flow experiments in various working conditions. A series of numerical 3D RANS simulations have been performed in order to directly compare numerical and experimental results. Mean pressure distributions have been measured on the nozzle model symmetry plane, in order to characterize the flow evolution along the walls of the plug. The presented results show a good agreement between numerical and experimental results.
Numerical suite for the design, simulation and optimization of cathode-less plasma thrusters
Authors: Souhair N.
Published: October 2023

Abstract. A numerical suite developed for the analysis and design of cathodeless plasma thrusters is presented. The suite includes a Global Model that estimates the thruster's propulsive performance by means of a balance of electron energy and population density, and a 3D numerical strategy to assess plasma behavior. The suite incorporates a FLUID and EM modules to solve plasma transport and electromagnetic wave propagation within the discharge chamber. The PLUME module, managed by the Starfish code, handles plasma dynamics in the magnetic nozzle using the electrostatic particle-in-cell approach. The suite has been validated against thrust measurements from a Helicon Plasma Thruster demonstrating the suite's potential for optimizing the design and operation of cathodeless plasma thrusters for space propulsion applications.
Particle migration modeling in solid propellants
Authors: Andriulli R.
Published: October 2023

Abstract. This work presents the development of an OpenFOAM solver to predict the migration of solid particles in concentrated suspensions under non-uniform shear flow. The solver modifies the pimpleFoam solver by implementing the conservation equation for particle volume fraction. It adapts the equation of motion for non-Newtonian flows and establishes a model for the viscous field using Krieger's correlation. The code is successfully validated by the experimental results from literature.
Neural networks for the identification of degraded components of aircraft fuel quantity system
Authors: Arcuri R.
Published: October 2023

Abstract. The physical and software architecture design of the fuel system of high-performance aircrafts is very complex and represents a challenging topic for aeronautic engineers. Among the main functionalities, there is the calculation of the on board fuel quantity, consisting in data computed by the fuel gauging sub-system, shown to the pilot on the cockpit display and used by the flight control system for aircraft controllability. Due to the large number of sensors and to a strongly ramified calculation code, faults and performance degradation of components, are difficult to be detected/isolated, since the operation would require an invasive investigation on the aircraft. To reduce the impact of the fault detection and isolation process in terms of time and costs, a digital twin of the fuel system has been developed and coupled with a condition-monitoring algorithm based on machine-learning methods. It is thus possible to quickly replicate the mission profiles during which the faults can occur, to calculate the residual fuel mass in parallel with the fuel computer and to precisely identify which component caused the system failure. A neural network, trained on experimental flight data, has been developed to provide reliable data. Once validated , the neural network is coupled with a 0D model that simulates the movement of the fuel inside the tank. In this way, it is possible to obtain the mass of fuel, simulating any flight mission profile. This approach optimizes the analysis of system malfunctions in terms of time and costs, highlighting unexpected mass values, otherwise undetectable. The reliability of the neural network can clearly be increased by training the algorithm with additional flight data, which can be derived from experimental or virtual flights simulated using the 0D model. The versatility of this process makes it applicable for different aircrafts as well as for further developments.
The ESA PANGAEA programme: training astronauts in field science
Authors: Massironi M.
Published: October 2023

Abstract. PANGAEA (Planetary ANalogue Geological and Astrobiological Exercise for Astronauts) is a field training course designed by the European Space Agency (ESA) that, since 2016, has imparted to ESA and NASA astronauts, and Roscosmos cosmonauts the basic theoretical and practical knowledge of geology and astrobiology and trained them in the field. Hence developing independent field skills, including working with a remotely located science team, is a key part of the training. For this reason, classroom and field lessons are tightly interwoven so that the concepts introduced in the classroom are shown in the field soon afterwards. The primary field sites selected for the course are the Permo-Triassic sedimentary sequences in the Italian Dolomites, analogue to the Martian alluvial plains ones, the impact geological environment of the Ries Crater, Germany, a comprehensive suite of volcanic emplacements and deposits in Lanzarote, Spain, and the anorthosite outcrops, analogue to lunar highlands rocks, in Lofoten, Norway. Each site is used as a base to deliver the main learning sessions, respectively: 1) Earth geology, rock recognition and sedimentology on Earth and Mars, 2) Lunar geology and impact cratering, 3) volcanism on Earth, Moon, and Mars, and astrobiology 4) intrusive rocks and lunar primordial crustal evolution. The four sessions are designed to increase the trainees’ autonomy in the field up to autonomously executed geological traverses including sampling activities. Whilst PANGAEA’s primary focus is astronaut training, where appropriate, technologies being developed for future missions are used to evaluate their performances in analogue field envi-ronments and to train the astronauts in using technologies that might support future missions.
Front cover for space optical telescopes. a legacy from ROSETTA to JUICE
Authors: Parzianello G.
Published: October 2023

Abstract. The reliability of a telescope's front cover for a space mission constitutes its primary demand, not to compromise the functionality of the entire instrument. Avoidance to expose possible reference surfaces to the external environment and contamination often drives the selection of the motion of the cover. The Front Door Mechanism (FDM) for the OSIRIS experiment of the ROSETTA mission has been developed and optimised to provide protection of the telescope, reliable functioning and being single point failure tolerant. Its combined translational and rotational motion allowed also the preservation of internal calibration surface for the entire duration of the mission. The ROSETTA mission was launched in 2004 and reached the comet in 2014 after several gravity assists, and deep space hibernation. It has been orbiting around the comet for roughly two years collecting enormous amount of data of the peculiar celestial body and ended in September 2016. As legacy of the successful design of the front cover for the ROSETTA mission, another cover mechanics (Cover Mechanism – COM) for the JANUS Optical Head Unit of the JUICE mission has been prepared with minor modifications to the initial design. All qualification has been performed and the JUICE mission has been launched successfully on 14 April 2023 and is now travelling towards Jupiter and its moons.
Experimental application of pseudo-equivalent deterministic excitation method for the reproduction of a structural response to a turbulent boundary layer excitation
Authors: Mazzeo G.
Published: October 2023

Abstract. The use of wind tunnels for studying the vibrational response of structures subjected to turbulent flows presents various challenges, such as background noise and complex setup requirements. This work introduces an alternative experimental method called X-PEDEm (eXperimental Pseudo-Equivalent Deterministic Excitation) that aims to reproduce an equivalent structural response to a Turbulent Boundary Layer (TBL) excitation without the need for a wind tunnel. X-PEDEm involves coupling the experimental acquisition of the structure's vibrational response with deterministic forces, such as an impulse force from a hammer, followed by post-processing. The method has been validated for different boundary conditions and flow speeds, offering versatility in recreating various types of TBL. While not an exact reproduction of turbulent flow-induced responses, X-PEDEm provides an optimal approximation with low time and resource requirements, making it easy to implement experimentally.
ADS-B driven implementation of an augmented reality airport control tower platform
Authors: Fadda T.
Published: October 2023

Abstract. This paper describes a real-world implementation of the solutions developed within the SESAR DTT Solution 97.1-EXE-002 project, which tested in a simulated scenario the use of Augmented Reality (AR) to assist the airport control tower operators (TWR). Following a user-centred design methodology, the requirements of a real-world live AR platform join with design concepts validated in previous projects, namely the Tracking Labels, the weather interface, and a low-visibility overlay, all used to increase the TWR situational awareness, performance and reactivity while reducing the workload. The designed AR platform performs the live tracking and visualization of real aircraft and surveillance information in the airport traffic zone. It bases on three key processes: the transmission of an ADS-B data flow to a Microsoft™ HoloLens2, the registration process of the AR platform, and the rendering of a real-time tracking system and other surveillance overlays. The concept has been first validated with the help of a TWR, preceding a technical validation to ensure the repeatability and reproducibility of the results. The results allow for defining new guidelines for the deployment in a control tower environment.
A tool for risk assessment after a catastrophic event during suborbital flight operations
Authors: Avanzini G.
Published: October 2023

Abstract. Suborbital flights represent a new frontier for the aerospace industry. Together with technological challenges and legal aspects, suitable tools for risk analysis are required to evaluate the potential damage produced by a catastrophic event during a suborbital flight. In particular, an explosion during the powered acceleration phase can cause dispersion of a large number of debris over a wide area, potentially harming the population living close to the launch site. A tool for the determination of the impact footprint of debris after an explosion is proposed, with the objective of supporting the definition of suitable ascent trajectories which reduce the risk for third parties below a publicly acceptable threshold. Legal aspects are also discussed.
Decision trees-based methods for the identification of damages in strongly damped plates for aerospace applications
Authors: Casaburo A.
Published: October 2023

Abstract. Damage identification and localization is fundamental in industrial engineering, since it helps perform corrective actions in time to reduce as much as possible system downtime, operational costs, perform quick maintenance and avoid failure. Recently, structural health monitoring has found in machine learning an extremely useful tool, making the monitoring of complex systems more manageable. In this work, composite plates manufactured with the purpose of damping vibrations in aerospace structures are experimentally tested; the strong damping suddenly reduces the vibrations, leading to responses very similar to one another, without noticeable or structured differences between undamaged and damaged plates. To overcome this issue, machine learning methods are applied. Decision trees-based methods are chosen since they provide a combination of feature selection capabilities and robust classification performances. The used methods are decision trees themselves and two boosting methods: AdaBoost and RUSBoost. All three methods perform well in identifying damaged plates, the type (thickness damage and debonding) and sub-type of damage (thickness/debonding of types A and B).
SHM implementation on a RPV airplane model based on machine learning for impact detection
Authors: Scarselli G.
Published: October 2023

Abstract. In this work an on-working Structural Health Monitoring system for impact detection on RC airplane is proposed. The method is based on the propagation of Lamb waves in a metallic structure on which PZT sensors are bonded for receiving the corresponding signals. After the detection, Machine Learning algorithms (polynomial regression and neural networks) are applied to the data obtained by the processing of the acquired ultrasounds in order to characterize the impacts. Furthermore, this work presents the development of a mini-equipment for acquisition and data processing based on a Raspberry Pi micro-computer.
Assessment and optimization of dynamic stall semi-empirical model for pitching aerofoils
Authors: Galli E.
Published: October 2023

Abstract. Dynamic stall is a phenomenon affecting aerofoils in unsteady flows which is particularly relevant in the helicopter field. Semi-empirical models are reliable tools to simulate this phenomenon, especially during preliminary design phases and for aeroelastic assessments. However, they need a large number of tuning parameters to provide reliable estimations of unsteady airloads. To face this problem, a parameter identification procedure based on sequential resolutions of optimization problems by means of a Genetic Algorithm is developed and it is applied to the state-space formulation of a modified version of the so-called "Second Generation” Leishman-Beddoes model. The effects of the optimal parameters on the model prediction capabilities are discussed and the variability of the parameters with reduced frequency is studied. The estimations of the unsteady airloads obtained by applying the optimization of parameters show a great improvement in the correlation of the experimental data if compared to the predictions obtained by using the parameters provided in literature, especially for pitching moments where the negative peaks are very well described. These improvements justify the need for optimization to set the parameters.
RANS transition model predictions on hypersonic three-dimensional forebody configuration
Authors: Cutrone L.
Published: October 2023

Abstract. Future space transportation systems will heavily rely on predicting and understanding Boundary Layer Transition (BLT) during atmospheric entry, especially in the hypersonic phase. Several models, compatible with RANS solvers, have yet been proposed, but not validated in the hypersonic regime. This paper focuses on evaluating prediction capabilities for such models on complex 3D geometries, using the International Boundary Layer Transition (BOLT) Flight Experiment as a test case.
A finite-volume hybrid WENO/central-difference shock capturing approach with detailed state-to-state kinetics for high-enthalpy flows
Authors: Bonelli F.
Published: October 2023

Abstract. This work shows novel space discretization capabilities of an innovative fluid dynamics solver able to deal with thermochemical non-equilibrium by using a detailed state-to-state model. The implementation of a WENO hybrid scheme is verified and thermochemical non-equilibrium effects are investigated by considering a high temperature shock tube test case. The work represents a first step to enable the solver to perform LES and DNS simulations of turbulent hypersonic flows.
Quantum computing CFD simulations: state of the art
Authors: Malinverno G.
Published: October 2023

Abstract. This document is meant to review and discuss the possible applications of Quantum computing in the area of computational fluid dynamics (CFD). A review of the current state-of-the-art of quantum computing applied to computational fluid dynamics has been carried out, highlining how the technology is promising but still in an early stage of development. Furthermore, within the approaches developed to solve CFD problems with the use of quantum algorithms and / or quantum computers, this article discusses a quantum algorithm approach, based on the Lattice Boltzmann Method and developed to the study of 2D flow around a cylinder, a model which can be related to several industrial problems and, in the future, modified to simulate the refrigeration cycle used in aeronautical environmental control systems (ECS). This preliminary code helped to highlight the inherent difficulties to implement a quantum algorithm but helped also to demonstrate the applicability of quantum computing.
Analysis of plasma formation during hypersonic flight in the earth atmosphere
Authors: Esposito S.
Published: October 2023

Abstract. In this study we investigate the formation of plasma in hypersonic flight and its impact on radio communications and radar tracking. The transfer of kinetic energy from the vehicle to the surrounding gas in the hypersonic regime leads to the formation of plasma, which can cause interference with electromagnetic waves. By conducting a numerical simulation campaign using Computational Fluid Dynamics (CFD), we are determining the critical Mach number and altitude conditions that lead to plasma formation. The plasma generated at the nose of the vehicle and its subsequent convection along the body and in the wake are the main subjects of our investigation. The simulations include physical models that account for chemical, vibrational and electron-electron energy non-equilibria, using a two-temperature approach. The results indicate the Mach numbers and altitudes at which plasma formation can significantly affect the propagation of electromagnetic waves.
Experimental investigation of the noise emitted by two different propellers ingesting a planar boundary layer
Authors: Falsi M.
Published: October 2023

Abstract. Novel-aircraft concepts consider the possibility of placing the propulsor very close to the fuselage to ingest the incoming airframe boundary layer. In this configuration, the engine takes in flow at a reduced velocity, thus consuming less fuel in the combustion process. However, this induces a series of noise consequences that alter the noise perceived by an observer. The present work reports an experimental investigation to compare the far-field noise directivity emitted by two different propellers ingesting a boundary layer at two different states. The experiments have been performed in the anechoic wind tunnel at the University of Bristol. The experimental setup consists of a propeller placed in the proximity of a tangential flat plate, which represents a simplified model of a fuselage. Two tripping devices placed 1 m (6.5 rotor radii) upstream of the propeller have been used to generate distinct boundary layer thicknesses. Results from two distinct propellers with three and five blades have been compared, varying the advance ratio J from 0.56 to 0.98. Far-field noise has been acquired using a microphone array positioned in the plate plane. The data have been analysed in the frequency domain, providing an extensive characterization of the far-field directivity. Results show a general increase in noise when the propeller ingests a thicker boundary layer. Furthermore, a change in directivity pattern is observed varying the advance ratio, suggesting a variation of the underlying physics. Finally, considering different J, the overall noise emission appears to be dependent on the number of blades.
Large Eddy simulations and Reynolds-averaged Navier-Stokes simulations of separation-induced transition using an unstructured finite volume solver
Authors: Carreño Ruiz M.
Published: October 2023

Abstract. The study aims to assess the capability of different methodologies in capturing the separation-induced transition phenomenon. This transition mechanism occurs when the flow separates from the airfoil surface, and transitions from a laminar to a turbulent state due to the amplification of the Kelvin-Helmholtz instability developed in the separated shear layer. The simulations employ high-order numerical methods for solving the Navier-Stokes equations, while the transition modeling for RANS is based on the γ-Re_θ transition model. LES enables prediction of the onset and location of transition and provides turbulent flow statistics.
Impact of a wedge in water: assessment of the modeling keyword, presence of cavitation and choice of the filter most suitable for the case study
Authors: Guagliardo D.
Published: October 2023

Abstract. The purpose of this paper is to compare the results obtained from a rigid wedge impacting water that is modelled using different techniques based on the SPH (Smoothed Particle Hydrodynamics) method. The study aims to evaluate the quality of the results, optimizing the computational time, which is obtained when the wedge is discretized as a section or as a half of it. The comparison of the results obtained considers the different materials that the ANSYS LS-DYNA software allows to assign to water through different keywords. The effect of cavitation on the pressures reached during the vertical impact was evaluated as a function of ambient temperature. Finally, given the high noise recorded in the pressure files, the study uses a filter created in MATLAB. The latter involves a double pass through the Kalman filter first and the Gauss filter later. All results obtained through the numerical method are compared with Von Karman and Wagner analytical theories.
Thermal fluid-structure interaction by discontinuous Galerkin methods
Authors: Gulizzi V.
Published: October 2023

Abstract. This research study presents a novel high-order accurate computational framework for thermal fluid-structure interaction problems. The framework is based on the use of block-structured Cartesian grids where level set functions are employed to define both the fluid and the solid regions. This leads to a mesh that consists of a collection of standard d-dimensional rectangular elements and a relatively smaller number of irregular elements at the fluid-solid interface. The embedded boundaries are resolved with high-order accuracy thanks to the use of high-order accurate quadrature rules for implicitly-defined regions. The fluid is assumed compressible and governed by the inviscid Navier-Stokes equations, whilst the solid region obeys the equations of thermo-elasticity within the small-strain regime. Numerical examples are provided to assess the capability of the proposed approach.
Conjugate heat transfer applied to transitory analysis for rocket engine cooling systems design
Authors: Barbato V.
Published: October 2023

Abstract. This study investigates the use of an in-house Conjugate Heat Transfer (CHT) numerical solver for the modelling of transient phenomena in liquid rocket engines active cooling systems. Heat transfer considerations place great limitations in the development of rocket engines and transient operative conditions are amongst the most critical. The current lack of models and numerical tools capable of accounting for the complexities of this time-dependent multi-physics problem, results in oversized cooling systems, long development times and increased risk of failure. The fine modelling of all the involved phenomena and their interaction with each other is crucial to achieve a correct prediction of the thermal fluxes and wall temperatures involved. Hence, CHT simulations are the state-of-the-art for this application. The CHT solver proposed in this work utilizes a partitioned coupling strategy where two extensively validated single-physics solvers exchange information through their interfaces at discrete time steps. A simplified version of the RL-10A-3-3A regenerative cooling jacket is considered as reference to test the strengths and the limits of this approach. Both a complete chilldown of the engine and part of the start-up transient have been simulated. The analyses performed show the ability of the solver proposed to deal with transient phenomena where fluid-structure interaction occurs. In addition, they provide a complete overview of the numerical issues related to the partitioned coupling approach. These preliminary results pave the way for further developments aimed at increasing the reliability of the solutions and extending the application field of the software developed.
A combustion-driven facility to study phenomenologies related to hypersonic sustained flight
Authors: Esposito A.
Published: October 2023

Abstract. This paper reports on the development of a new Blowdown-Induction Facility driven by two different Oxy-Fueled Guns. The facility is conceived and realized to simulate different phenomenologies and flow conditions related to hypersonic sustained flight.
Numerical tank self-pressurization analyses in reduced gravity conditions
Authors: Rossetti F.
Published: October 2023

Abstract. In this study, a suitable numerical methodology to study the self-pressurization phenomenon inside a cryogenic tank, in a reduced gravity environment is proposed. This methodology is validated with the results of a benchmark self-pressurization experiment, carried out in the liquid hydrogen tank of the second stage of the Saturn IB AS-203 vehicle. The time-varying acceleration and heat flux due to solar radiation to which the tank was exposed during the experiment, have been modeled in our analysis. Finally, the numerical results show that the proposed methodology allows to reproduce the experimental data with a reasonably good accuracy.
Predicting noise spectrum of a small drone rotor in a confined environment: a lattice Boltzmann Vles analysis
Authors: Colombo R.
Published: October 2023

Abstract. The objective of this paper is to study the predictive capabilities of a Very-Large-Eddy-Simulation CFD solver for the simulation of the flow past a small drone propeller blade. The solver is based on a Lattice-Boltzmann Method coupled with an FW-H acoustic analogy to compute the far field noise. The method is able to cope with the anechoic test chamber to predict the complex flow-field and the characteristic boundary layer phenomena (such as laminar separation, transition and reattachment). The acoustic hybrid formulation provides tonal and broadband noise radiation in agreement with the experimental data. Frequency spectrum prediction exhibited a strong low-frequency tonal contribution at multiples of the blade passing frequency related to the interaction with coherent vortical structures in hover, and a high-frequency broadband hump due to the laminar separation bubble at high advance ratio.
Nonlinear transient analyses of composite and sandwich structures via high-fidelity beam models
Authors: Filippi M.
Published: October 2023

Abstract. In this study, we employ low and high-fidelity finite beam elements to conduct geometrical nonlinear transient analyses of composite and sandwich structures. The equations of motion for various structural theories are derived in a total Lagrangian scenario using the Carrera Unified Formulation. The unified formalism's three-dimensional nature enables us to include all components of the Green-Lagrange strain tensor. To solve the equations, we utilize the Hilber-Hughes-Taylor (HHT)-α algorithm in conjunction with a Newton-Raphson procedure. We present the dynamic response of a sandwich stubby beam subjected to a step load, calculated using both equivalent-single layer and layer-wise approaches. Additionally, we discuss the effects of geometrical nonlinearity.
Coupling effect of acoustic resonators for low-frequency sound suppression
Authors: Catapane G.
Published: October 2023

Abstract. Acoustic resonators like Helmholtz resonators, micro-perforated panels and quarter wavelength tubes are employed to suppress tonal noise for several industry application. The issue related to the design of these resonators is their bulkiness for low-frequency application and their narrow band behaviour. In this paper, microperforated panels and coiled quarter wavelength tubes are coupled in series and in parallel, tested inside impedance tube for sound absorption. The experimental samples are 3D printed with filament (PLA) additive manufacturing technique. The two acoustic devices are coupled and tested to reach broadband low-frequency noise suppression just by positioning one respect to the other in series or in parallel. The reported results demonstrate that the tonal behaviour of the acoustic devices can lead to enlarged absorption if they are tuned at similar frequencies. The disposition of the acoustic resonators and their frequency tuning hardly impact absorption: indeed, anti-resonance and filtering effect are experienced for series configuration, while parallel configuration is the sum of the two acoustic devices standalone absorption behaviour.
Remote sensing validation with in-situ measurements for efficient crop irrigation management
Authors: Terlizzi I.
Published: October 2023

Abstract. The multi-spectral data acquired with either satellite imagery, UAV or tethered and stratospheric balloons can be used to calculate vegetation indices directly related to the well-being of the crops providing a quantitative information about its health and growth. The vegetation indices are calculated combining measurements from different parts of the electromagnetic spectrum, typically in the visible and near-infrared ranges. The aim of this work is to integrate the remote sensing data with in-situ collected measurements in order to validate remote observations for monitoring soybean water status and requirements. The study is conducted in Italy on a field of 160 x 40 m2, divided into four plots of 40 x 40 m2; two of them are irrigated at 100% of the CRW (Crop Water Requirement) and two irrigated at 70% of CWR. In each plot tensiometers and capacitive probes directly measure the soil moisture, along with a climate station used to monitor environmental parameters. The in-situ data are correlated with multi band satellite images by the PlanetScope constellation providing a ground resolution of 3 m. The use of UAV or balloons is needed to monitor the diurnal variation of the indices, as the satellite revisit time is once per day around 9:00 and 10:00 UTC on the site. The balloon payload is equipped with commercial cameras and dedicated filters to acquire images in the same spectral bands as satellites. The importance of this study lies in the possibility of managing the fields irrigation basing on the actual physiological need of the crop rather than relying on a predefined timetable, resulting in a more efficient and environmentally responsible irrigation. The article will present the methodology and the instruments applied, together with the results obtained.
A static, refractive and monolithic Fourier spectrometer for an HEMERA balloon flight
Authors: Frassetto F.
Published: October 2023

Abstract. In this work we present the characteristics of a static Fourier transform spectrometer designed for a balloon flight and meant to test the instrument in an actual working environment. The flight campaign has been provided within the HEMERA Research Infrastructure. The interferometric assembly, the core of the instrument, is made with only refractive and reflective surfaces, without diffraction gratings. It is realized with four glass elements that are glued in a single monolithic structure with no spacers or framed supports. There are no hollow spaces, thus improving the mechanical stiffness. The spectral band accessible to the presented optical design is 450 – 850 nm and the working spectral region can be chosen to be either 550 – 850 nm or 450 – 550 nm. The spectral resolution is variable as it is driven by the refractive index of the used glasses in the considered spectral region. In this design, the resolution varies from 1500 at 550 nm to 200 at 800 nm and to 4000 at 450 nm. The total field of view of the instrument is 3 degrees. All the optical elements used to operate the spectrometer are installed on a 3D printed structure. This is possible due to the low sensitivity of the instrument to vibrations. The interferometric assembly has undergone thermal test to quantify the temperature range it can tolerate. We will present the instrument design and the first results of the flight campaign.
On the influence of airframe flexibility on rotorcraft pilot couplings
Authors: Talamo C.
Published: October 2023

Abstract. A set of numerical simulations of the interactional dynamics of the pilot-rotorcraft system is performed. The aim of the numerical analysis is to evaluate the stability of the closed-loop system in hovering conditions, focusing on the influence of the first airframe flexible mode, the one with the most participation in relative motion between the main rotor and the pilot’s seat and closest in frequency to pilot-vehicle interaction. Two approaches are employed. First, a linear analysis, in which the modal representation of the airframe flexible mode is added to a linearized model of the helicopter vertical motion and the helicopter dynamics is coupled with a single degree of freedom linearized model of the pilot biomechanics. Subsequently, a multibody model of the helicopter is coupled with the same linear model of the pilot, trimmed in hover and perturbed by a vertical gust. A sensitivity analysis shows that such mode has a significant influence on the stability of the closed loop system, especially if its frequency is close to the natural frequency of the pilot’s biomechanics, as one might expect.
Ascent trajectory of sounding balloons: dynamical models and mission data reconstruction
Authors: Bettanini C.
Published: October 2023

Abstract. Small sounding balloons are a fast and cost-effective transport system to lift up scientific payloads up to stratospheric burst altitudes below 40 kilometres; during ascent and descent phase dedicated instruments may be operated to monitor atmospheric parameters and optical payloads may be used for remote observation. This work will focus on the reconstruction of the trajectory of the ascent phase, which is the longest and dynamically less perturbed part of the flight; in this section the dynamics of the flight system is determined by the lift of the balloon guiding the vertical motion and the local winds controlling the horizontal motion. The presented reconstruction algorithm is based on a linear quadratic estimation predictor corrector using the standard equations of motions in ECEF system to propagate the simulation and the measurement of the on-board sensors (triaxial accelerometer, GPS, pressure and temperature sensors) to correct the estimation and reduce the uncertainty in the reconstruction, which is mainly related to the value of balloon canopy drag coefficient Cd, the lifting gas volume and local wind perturbations. Two different balloon flights, both launched within a joint effort between teams by University of Padova and University of Pisa, are considered: one conducted during daytime, the other in night time. The different environmental conditions and in particular the different temperature evolution within the lifting balloon in the day flight due to Sun heating provide a good proving ground to investigate sensitivity of algorithm to environmental conditions. The prediction of flight dynamic models implementing horizontal and vertical equations of motion are compared with real mission data acquired by on board systems, highlighting the influence of local perturbations on the foreseen ascent trajectory.
Exploring aerospace advancements and global collaborations: a comprehensive analysis of MCAST's aerospace program in Malta
Authors: Barilaro L.
Published: October 2023

Abstract. This paper provides an overview of the Aerospace Program at the Malta College of Arts, Science and Technology (MCAST). The program comprises of four main projects that aim to address different challenges in the aerospace industry, in particular in the field of protection of aerospace structures and systems from space debris impacts. The first project focuses on the development of 3D printed Kevlar shields for aerospace applications. The outcome of this project is the development of repair strategies for inflatable manned modules in space and efficient small satellite shields. The second project describes the use of cold-welding phenomenon for spacecraft repair, in collaboration with South East Technological University (SETU), Ireland. The project aims to develop an experimental test rig to apply custom repair patches of different materials to pre-damaged metallic structures and monitor the performance of the adhered joint in low orbit and during re-entry. The third project presents a collaboration between MCAST and the University of Padova to develop a single stage Light-Gas Gun (LGG) impact facility in Malta. Finally, the paper discusses MCAST's participation in Malta's third space bioscience experiment launched to the International Space Station led by the University of Malta. The experiment aims to investigate how microgravity affects the behaviour of foot ulcer microbiomes in Type 2 Diabetes Mellitus patients. The project marks a significant milestone for both MCAST and the University of Malta. The projects presented in this paper reflect MCAST's commitment to contribute to the advancement of the aerospace industry and offer new opportunities for research, development, and commercialization.
Comparison of lattice core topologies in sandwich structures
Authors: Mantegna G.
Published: October 2023

Abstract. Hybrid sandwich structures are often used in the aviation industry thanks to their high strength-to-weight ratio and resistance to bending and buckling. Today, through Additive Manufacturing technologies, it is possible to use different materials to create topology-optimized structures with complex shapes using lattice structures. In this work, a numerical approach is proposed to study the behaviour of a hybrid sandwich structure which can be used as a reinforcement for a control surface of a lightweight aircraft. A comparative analysis is conducted between a conventional honeycomb lattice core and lattice truss core structures.
Surface node method for the peridynamic simulation of elastodynamic problems with Neumann boundary conditions
Authors: Scabbia F.
Published: October 2023

Abstract. Peridynamics is a nonlocal theory that can effectively handle discontinuities, including crack initiation and propagation. However, near the boundaries, the incomplete nonlocal regions are the cause of the peridynamic surface effect, resulting in unphysical stiffness variation. Additionally, imposing local boundary conditions in a peridynamic (nonlocal) model is often necessary. To address these issues, the surface node method has been proposed for improving accuracy near the boundaries of the body. Although this method has been verified for a variety of problems, it has not been applied for elastodynamic problems involving Neumann boundary conditions. In this work we show a numerical example of this case, comparing the results with the corresponding peridynamic analytical solution. The numerical results exhibit no stiffness variations near the boundaries throughout the entire simulation timespan. Therefore, we conclude that the surface node method allows to effectively solve elastodynamic peridynamic problems involving Neumann boundary conditions, with improved accuracy near the boundaries.
Adaptive finite elements based on Carrera unified formulation for meshes with arbitrary polygons
Authors: Cinefra M.
Published: October 2023

Abstract. The new Adaptive Finite Elements presented are based on Carrera Unified Formulation (CUF) that permits to implement 1D and 2D elements with 3D capabilities. In particular, by exploiting the node-dependent kinematic approach recently introduced and incorporating the FEM shape functions with the CUF kinematic assumptions in unique 3D approximating functions, it is demonstrated that new mesh capabilities can be obtained with the use of presented elements by easy implementation. A classical patch test is performed to investigate the mesh distortion sensitivity.
Polymer matrices for composite materials: monitoring of manufacturing process, mechanical properties and ageing using fiber-optic sensors
Authors: Airoldi D.
Published: October 2023

Abstract. Composite materials have gained significant prominence in the field of aerospace engineering owing to their exceptional strength-to-weight ratio, making them well-suited for structural applications. However, these materials are susceptible to degradation due to exposure to environmental factors, such as humidity and temperature changes. Detecting and quantifying such damage presents considerable challenges, particularly in the case of cyclically loaded components. Fiber Bragg Grating (FBG) sensors provide a non-destructive means of monitoring composite material degradation by leveraging optical reflection to measure changes in strain and temperature. This research aims to assess and validate a methodology for employing FBG sensors to effectively monitor the degradation of composite material matrices. The investigation mainly consists in characterizing the correlation between FBG sensor wavelength shifts and the strains incurred due to the manufacturing process, moisture absorption, and thermal effects. The anticipated outcomes hold the potential to enhance the reliability and safety of composite structures employed within the aeronautical domain.
A boundary element method for thermo-elastic homogenization of polycrystals
Authors: Fonzi N.
Published: October 2023

Abstract. A computational framework for thermo-elastic homogenization of polycrystalline materials is proposed. The formulation is developed at the crystal level and it is based on the explicit Voronoi representation of the micro-morphology. The crystal thermo-elastic equations are formulated in an integral form and numerically treated through the boundary element method. The presence of volume integrals, induced by the inherent physics of the thermo-elastic coupling, is addressed through a Dual Reciprocity Method (DRM), which allows recasting the formulation in terms of boundary integrals only. The developed methodology is applied for estimating the homogenized thermo-elastic constants of two widely employed ceramic materials. The method may find applications in multiscale analysis of polycrystalline structural component.
Can we use buckling to design adaptive composite wings?
Authors: Bisagni C.
Published: October 2023

Abstract. In aeronautics, buckling has long been considered as a structural phenomenon to be avoided, because characterized by large out-of-plane displacements and therefore by losing the ability to sustain the designed loads. Several recent studies show the possibility to allow composite stiffened panels of primary aeronautical components to work in the post-buckling field so to potentially reduce the structural weight. The present study aims to control buckling behavior of composite structural components for future adaptive wings using novel tailorable and effective mechanisms. Instead of the traditional design against buckling, the idea is to use the nonlinear post-buckling response to control stiffness changes which redistribute the load in the wing structure. Numerical studies are at first conducted on a composite plate and then implemented in a simplified thin-walled composite wing box, where stiffness changes is controlled using buckling.
Immersed boundary-conformal coupling of cylindrical IGA patches
Authors: Guarino G.
Published: October 2023

Abstract. In this work an Immersed-Boundary-Conformal coupling method for coupling shells is presented. The linear elastic static analysis is carried out using the Kirchhoff-Love shell model. The variational statement is discretized with an Isogeometric Analysis approach. The method employs auxiliary shell patches conformal to the interfaces which are coupled to the main ones using an Interior Penalty formulation. Results showing the potential of such approach to study multi-component shell structures are provided.
Structural batteries challenges for emerging technologies in aviation
Authors: di Mauro G.
Published: October 2023

Abstract. In a global context where modern societies need to move towards greater environmental sustainability, ambitious targets to limit pollutant emissions and combat climate change have been set out. Concerning the aviation sector, research centers and industries are carrying out new aircraft designs with increased use of electrical energy onboard aircraft both for non-propulsive and propulsive purposes, leading to the concepts of More Electric Aircraft (MEA), Hybrid Electric Aircraft (HEA) and All-Electric Aircraft (AEA). Despite the expected flight emissions reduction, new potential air transportation missions, safer flights, and enhanced design flexibility, there are some drawbacks hindering the trend to HEA solutions, strictly bounded to the limited performance of traditional battery systems. The reference is to low energy and power densities, which impact on aircraft weight and flight performances. A new technology, namely structural battery, combining energy storage and load-bearing capacity in multifunctional material structures, is now under investigation since capable to mitigate or even eliminate barriers to the electrification of air transport sector. Although, the deployment of this technology raises relevant questions regarding airworthiness requirements, which need to be applied when considering such multifunctional materials. The purpose of the presented activity is to take a step towards the definition of aircraft certification requirements when dealing with structural batteries, considering them both as a structure and as a battery, to maintain unchanged or even improve the level of safety in all normal and emergency conditions.
Deep learning algorithms for delamination identification on composites panels by wave propagation signals analysis
Authors: Monaco E.
Published: October 2023

Abstract. Performances are a key concern in aerospace vehicles, requiring safer structures with as little consumption as possible. Composite materials replaced aluminum alloys even in primary structures to achieve higher performances with lighter components. However, random events such as low-velocity impacts may induce damages that are typically more dangerous and mostly not visible than in metals. Structural Health Monitoring deals mainly with sensorised structures providing signals related to their “health status” aiming at lower maintenance costs and weights of aircrafts. Much effort has been spent during last years on analysis techniques for evaluating metrics correlated to damages’ existence, location and extensions from signals provided by the sensors networks. Deep learning techniques can be a very powerful instrument for signals patterns reconstruction and selection but require the availability of consistent amount of both healthy and damaged structural configuration experimental data sets, with high materials and testing costs, or data reproduced by validated numerical simulations. Within this work will be presented a supervised deep neural networks trained by experimental measurements as well as numerically generated strain propagation signals. The final scope is the detection of delamination into composites plates for aerospace employ. The approach is based on the production of images trough signal processing techniques and on employ of an image recognition convolutional network. The network is trained and tested on combinations of experimental and numerical data.