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Aerotecnica Missili & Spazio : Journal of Aerospace Science, Technologies & Systems
Number of Followers: 0  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0365-7442 - ISSN (Online) 2524-6968
Published by Springer-Verlag Homepage  [2574 journals]
  • AIDAA News #3
    • PubDate: 2019-09-01
       
  • Thermal Influence of the Screw Axial Load on a 1-mm Accuracy Laser Ranged
           Satellite
    • Abstract: This work explores the role of the screw axial load on the temperature experienced by the mounting set of a Cube Corner Retroreflector (CCR) in a spherical satellite, designed to achieve 1-mm accuracy in satellite laser ranging. Since thermal gradients inside CCRs induce refractive index gradients, changing the optical behaviour, thermal analysis and simulation are needed to ensure the best performances. The screw axial load influences the thermal interface resistances between the rings of the mounting set, changing their thermal behaviour. It is important to study the temperature, not only for the thermal gradients inside a CCR, but also to check that the Kel-F mounting rings do not overcome their maximum operative temperature. Two models have been realized in the commercial software C&R Thermal Desktop®: a model to simulate the entire satellite behaviour and a detailed model to represent the cavity which includes the CCR and its mounting set. Different on-orbit scenarios are analyzed, focusing on the influence of the screw axial load in each of them.
      PubDate: 2019-09-01
       
  • Numerical Methods for Efficient Fluid–Structure Interaction
           Simulations of Paragliders
    • Abstract: After specifying the general context and needs of the paragliding industry, a new model to compute paraglider cloth dynamics is presented. Applications in research and development are then shown. Results are very promising: using simulations is drastically changing the way paragliders are being developed. Then the firsts steps towards the use of immersed boundaries with Lattice Boltzmann method for the highly coupled, transient high fidelity fluid–structure interaction simulation of paragliders are presented. Despite strong bias due to under-resolved boundary layers, numerical results of the cloth deformations are in an acceptable agreement with wind tunnel measurements conducted in a previous study on a small and simple parachute geometry.
      PubDate: 2019-09-01
       
  • Aerosols’ Impact on Optical Satellite Transmission
    • Abstract: Optronic sensors on board satellites are used for remote sensing and telecommunications, but are submitted to meteorological conditions and among them cloud cover and aerosols. Aerosol presence in the field of view could be one of the key factor limiting performances of these sensors. The goal of this study is to predict optical transmission of a satellite’s sensor due to aerosols with a Monte Carlo method. Geometrical and optical properties required to build the model are obtained from CloudAerosol Lidar with Orthogonal Polarization (CALIOP) measurements. Atmospheric scenes containing aerosols are generated and transmission spectra are obtained along the line-of-sight of a virtual satellite. To evaluate the impact of aerosols on the optical link, we computed the probability that the transmittance along the LOS is higher than a given threshold. Different areas are selected and relevant satellites configurations are investigated: geostationary, Low-Earth-Orbit, nadir view angle, or tilted view. Results’ discussion points out the impact of climates and environments but also the importance of the satellite instruments angle of view in the optical transmission between ground stations and satellites.
      PubDate: 2019-09-01
       
  • Methodology to Analyse Handling Qualities Under Force Gradient Transitions
           of an Active Sidestick
    • Abstract: In recent years, active sidesticks have been used in concepts of civil aircraft enabling more intuitive force-feedback, amongst other improvements. But mode degradations or mechanical failures can cause sudden transitions in the force–deflection gradient. During manual control, such an event can lead to overcontrol by the pilot and into pilot-in-the-loop oscillations. A methodology is developed to investigate the impact of these events on pilot–vehicle system dynamics. Tracking tasks are designed to repeatedly elicit pilot reactions comparable to those of sudden and unexpected transitions. First simulator tests proved the methodology to be effective in surprising the pilot and preventing memorisation of the task. The tests reveal that transitions have a greater impact when pilots are well adapted and force gradients decrease.
      PubDate: 2019-09-01
       
  • Statistical Characterization of Biomimetic Gecko Adhesives
    • Abstract: This paper presents a way to characterize the strength of bioinspired gecko-adhesives. These are the most promising mechanisms, so far, which enable controlled adhesion (i.e. turning it on and off). They emulate the forces present in geckos’ fingertips to stick temporarily to surfaces without any preconditioning and keeping them intact. Moreover, they do not need of any specific environment to work, which makes them specially useful for space applications such as grippers, or robots capable of climbing the outer surface of a space vehicle to perform inspections or repairs. To further enhance their adhesion strength, a high voltage electrostatic field is usually applied. However, while these adhesives tend to perform very well on smooth surfaces, the nefarious effects of surface roughness are yet uncharacterized. In this paper, we developed a statistical method to characterize those effects based on the concept of effective surface defects, and without need of a yet intractable direct measurement. In particular, controlled surface defects on adhesives themselves were statistically analyzed through a sample of over 2000 experiments; matching them with the statistical results. Through this process, the validity of the analysis lead to a way of calculating effective surface defects on substrates by considering the dual problem. Because this method does not require substrates to have any specific surface conditions, its use might be extended to study adhesion on more challenging surface morphologies such as that of kapton thermal covers, which often appear on space vehicles.
      PubDate: 2019-09-01
       
  • Delta-DOR Observations Using VLBI Antennas
    • Abstract: Delta-DOR (differential one-way ranging) is a technique which addresses the problem of orbit determination of a target deep-space spacecraft, in particular by determining its angular position in the sky. This can be achieved by means of analyzing both quasar signals, using this radio source as a calibrator, and a proper signal transmitted by the target spacecraft. These signals should be received by two or more stations, possibly set at a large distance from each other. Nowadays, European Space Agency (ESA) can count only on a few stations, more precisely the largest ones, since large signal-to-noise ratios are required to acquire the faint transmissions involved. This study has the aim to exploit a different set of stations, the ones belonging to the very long baseline interferometry (VLBI) network, to perform Delta-DOR measurements. VLBI antennas have in general the right hardware requirements but lack a proper recording output; therefore, a software translation of the recorded signal is required. As a proof-of-concept of the proposed technique, a shadow pass, involving an Italian VLBI station, of a standard ESA Delta-DOR session has been scheduled. The recorded data were successfully translated and analyzed by means of the ESA’s software correlator, showing the feasibility of this innovative procedure.
      PubDate: 2019-09-01
       
  • Getting Information on Impact Damage of Carbon Fibre-Reinforced Composites
           from Thermal Signature Evolution
    • Abstract: The susceptibility of carbon fibre-reinforced polymers to impact damage is a well-known problem and drives efforts of researchers towards the creation of new materials, which may be able to contrast impact. Being difficult to predict the behaviour of a newly conceived material during the design phase, specific tests are necessary to assess its impact resistance. This is generally obtained through lengthy tests, which, amongst others, are aimed to find a relationship between the impact energy and the size of the produced damage. A fast and relatively cheap way appears to be in-line monitoring of impacts with an infrared imaging device; the obtained information can contribute to enhance the knowledge of impact damage mechanisms. The attention of this paper is mostly focused on post-processing and analysis of thermal images, which were recorded during in-line monitoring of impact tests. The obtained results are compared with the existing literature and a general agreement is found. As important points, from mechanical-coupled thermal effects, it is possible to get information about some characteristic times such as the impact duration and the time at which peak contact force occurs as well as to individuate damage initiation. These findings can be achieved in a remote way, without any contact with the part under investigation and without any interference with the test execution.
      PubDate: 2019-08-14
       
  • Rapid Prototyping of Variable Angle-Tow Composites
    • Abstract: The recent development of new manufacturing techniques of composite structures, e.g., additive manufacturing (AM) techniques, allows for going beyond the classical design rules, thus leading the designer to find innovative and more efficient solutions like the variable angle-tow (VAT) composites. VAT composites allow taking advantage from the benefits related to the curvilinear fibre path in the most effective way, though their utilisation unavoidably implies an increased complexity of the design process. In fact, VAT composites are characterised by a large number of design variables involved at different scales. Accordingly, a dedicated multi-scale optimisation approach able to integrate both mechanical and technological requirements (to ensure the manufacturability of the solution) must be developed. In this work, the multi-scale two-level (MS2L) optimisation strategy for VAT laminates is used, for the first time, to design a VAT laminate by taking into account the manufacturing requirements related to the fused filament fabrication (FFF) and continuous filament fabrication (CFF) processes. To show the effectiveness of the MS2L strategy in terms of manufacturability of the optimised solutions, a prototype of the VAT plate is realised by developing an ad hoc CAD model interfaced with the CFF machine. The realised prototype matches very well the optimum fibre path resulting from the MS2L strategy and the importance of including technological constraints within the design process is highlighted.
      PubDate: 2019-08-05
       
  • Ultrasonic-GW Tomographic Analysis and Probabilistic Reconstruction
           Approach for SHM Applications
    • Abstract: We present a structural health monitoring (SHM) paradigm based on the active generation, detection, and processing of guided ultrasonic waves (GUWs). The paradigm is tested on an aluminum plate instrumented with an array of six piezo-wafer transducers. These transducers are part of a unified SHM system where the non-destructive evaluation technique of acoustic emission, electromechanical impedance, and guided ultrasonic waves are integrated in the same hardware/software unit. In the study presented in this paper, we analyzed the ultrasonic data using a tomographic and a probabilistic reconstruction algorithm based on different reconstruction techniques and/or several damage ultrasonic parameters analysis. The objective is to enhance the detection and localization of damage that, in this study, consisted of a permanent magnet attached to the plate. The damage is, therefore, represented by a small mass added to the plate. The results presented here show that the tomographic reconstruction algorithm is robust and can be integrated into the unified SHM system to reduce false positives/negatives. A comparison with a probabilistic reconstruction algorithm is also presented.
      PubDate: 2019-06-01
       
  • A.I.D.A.A. News #2
    • PubDate: 2019-06-01
       
  • Possible Trajectories for Electric Solar Wind Sail Validation
    • Abstract: The aim of this paper is to analyze a potential mission scenario that could be used to perform an in situ test of the Electric Solar Wind Sail. Such an advanced propulsive system works only outside the Earth’s magnetosphere; so, a translunar mission (where the spacecraft is supposed to be inserted as a secondary “piggyback” payload) is hypothesized, in which at least a part of the spacecraft trajectory is around or beyond the Moon’s orbit. The analysis of possible selenocentric trajectories is conducted with a three-dimensional generalization of the classical patched conic approximation. In particular, two cases are considered: a closed selenocentric orbit, and a Moon flyby that inserts the spacecraft on a post-flyby geocentric orbit with at least some branches outside the Earth’s magnetosphere.
      PubDate: 2019-06-01
       
  • CIRA Preliminary Roadmap for the Development of Mars Research Project
    • Abstract: Human and robotic exploration is foreseen to be one of the next steps in human space colonization, and it is growing the common vision that Moon, on the pathway to Mars, is the outpost to extend human presence in deep space. At the same time, technologies and knowledge derived from space exploration tests, key factors for a more affordable, easier and quicker access to Space, will expand our understanding of the Universe, and create economic opportunities. In this scenario, CIRA intends to support the national community, involved in space colonization projects, through the Mars research project. The project is conceived as a technology-driven effort aimed at maturing a number of technologies and engineering tools necessary to enable future space exploration and colonization missions. Indeed, the project goal is to develop experimental infrastructures and necessary competences for future human and robotic Martian, Lunar and cis-Lunar exploration and colonization missions, supporting industries, universities and national research centres, to meet the challenges of this extremely promising and competitive sector. The present paper gives an overview of CIRA development plan related to Moon and Mars exploration and colonization, focusing on the design and realization of test analogue facilities and the development of enabling technologies. In the definition of the roadmap, a particular emphasis will be given to the facilities concept proposed and constituted by the following research areas: Environmental facility, Robotic laboratory, Aeolic Tunnel and Life Support System area.
      PubDate: 2019-06-01
       
  • Basic Technology for Smart Multifunctional Components with Embedded
           Electronics using Fused Filament Fabrication
    • Abstract: In this work, we discuss the use of the space-proven Fused Filament Fabrication (FFF) technology for the realization of smart multifunctional components. FFF is an Additive Manufacturing (AM) technology from the Material Extrusion set. The typical FFF procedure, intended to produce plastic component for rapid prototyping applications, is firstly introduced. A modified approach enabling the implementation of electric connections and inclusion of components in the manufacturing process is presented. All the phases of the digital manufacturing, as AM is also known, must be reconsidered to allow the insertion of internal circuitry. Key points such as material characterization and digital model creation are discussed. As far as this last point is concerned, several strategies for 3D digital model creation are presented along with a description of essential constituting elements and FFF-specific fabrication timelines. These are organized according to user’s will to insert or FFF-manufacture electric connections and part-consolidation considerations. All these strategies come along with illustrative test cases, demonstrating the effectiveness of the procedure proposed in this work. This work presents an alternative method enabling to turn a typical rapid-prototyping system into a system to potentially fabricate smart components.
      PubDate: 2019-06-01
       
  • Analytical Prediction of High-Velocity Impact Resistance of Plane and
           Curved Thin Composite Targets
    • Abstract: Resistance to ballistic impacts is a key requirement for an effective use of composite structures in many engineering applications. In fact, when fiber-reinforced composites are subject to high-velocity impacts (HVI), they are likely to suffer complete perforation, eventually causing the dramatic failure of the overall system. Moreover, elements with shielding requirements often feature nontrivial curvatures, so that their use in many engineering applications must undergo a precise evaluation of the effects of curvature on their resistance to impacts. The objective of the present work is to present an analytic formulation to model high-velocity impacts on both plane and curved (cylindrical and spherical) thin woven fabric composite targets, relying on the geometric and the elastodynamic characteristics of the target.
      PubDate: 2019-06-01
       
  • Biodynamic Modeling Techniques for Rotorcraft Comfort Evaluation
    • Abstract: This work shows how different occupant biodynamic modeling techniques are integrated in a rotorcraft design environment and discusses the resulting differences in comfort assessment. Three modeling techniques, that are used for biodynamic characterization, are considered: lumped parameter, finite element and multibody dynamics. These models are identified for the same gender, age, weight and height, and then integrated into a virtual helicopter environment with a seat–cushion interface. A generic helicopter model is used to demonstrate the approach. For each of the three techniques, the vertical acceleration levels at the human–helicopter interface, as required by vibration regulations, and at the head are evaluated up to 30 Hz. At a first glance, it is observed that the lumped parameter is the easiest to implement in terms of model set-up. However, the use of lumped parameter models is limited to the population groups that they are identified from, and thus are not as flexible as the finite element and multibody ones in developing biodynamic models for individuals of an arbitrary population percentile. Furthermore, through numerical analysis, it is found that the differences are not very significant in terms of accelerations at the human–seat interface. Therefore, for comfort-related issues, the use of more complex models is not justified, unless complicated comfort assessments other than human interface accelerations are required. On the other hand, it is observed that the spine dynamics can play a significant role in estimating the acceleration of head; therefore, the sophisticated finite element and multibody dynamics models redeem their higher modeling cost and computation time when the head–neck health of occupants is considered.
      PubDate: 2019-06-01
       
  • A.I.D.A.A. News
    • PubDate: 2019-03-01
       
  • Drop Test Simulations of Composite Leaf Spring Landing Gears
    • Abstract: This paper deals with the investigation of the static and dynamic behaviors of composite leaf spring landing gears during the landing phase of an aircraft. An accurate simulation of the overall landing gear mechanism needs to be performed in order to evaluate the forces that result on the fuselage during the impact of the aircraft on the ground. Thus, a model of the leaf spring landing gear was built through the Finite Element Method (FEM), and then its motion was analyzed with a Multibody Simulation (MBS). The results show the force transmitted to the fuselage by straight and curved leaf springs. Different values of thickness and materials were taken into account, in order to evaluate design sensitivities. In conclusion, the relationship between the geometry and material characteristics of the composite landing gear and the force on the fuselage is highlighted in graphs and tables, which can be used for future design and developments of landing gear systems.
      PubDate: 2019-03-01
       
 
 
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