I European Conference On Multifunctional Structures (EMuS2019), June, 11-12, 2019

The main aim of the Multifunctional Structures conference is to share among the scientific and the industrial community the recent advances made on mechanical structures with multiple functions. Recent advances in material technology have improved the additional capacities of such structures in a way in which now, their added functionalities can be as important as their mechanical performance.

Multifunctional Structures conference looked into a wide range of structural systems, serving different purposes: structures with embedded ... show more

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Analysis of Radar Absorbing FSS on Foldcores and Honeycombs
J. Es, A. Hulzinga, P. Tensen, H. Schippers, R. Heijmans, M. Journee

I European Conference On Multifunctional Structures (EMuS 2019).

Abstract
The objective of the paper is to investigate the radar absorption of honeycombs and foldcores with printed conductive patterns. These structures can be manufactured by first printing conductive Frequency Selective Surfaces (FSS) on planar substrates, which then can be used to shape foldcores and honeycombs by means of specific manufacturing technologies. Foldcores can be considered as intermediate shapes between planar sheets (where the printed patterns are perpendicular to the impinging radar waves) and honeycombs (where the printed patterns are parallel to the impinging radar wave). It is shown that the radar absorbing properties of the design strongly depend on the electrical conductivity of the paint, the size of the printed patterns and the orientation of the printed patterns with respect to the impinging wave. It is shown that a planar FSS has a maximum absorption of 50%, while foldcores and honeycombs may obtain a higher absorption due to the fact that the patterns are orientated under an angle with respect to the propagation direction of the wave.
Abstract
The objective of the paper is to investigate the radar absorption of honeycombs and foldcores with printed conductive patterns. These structures can be manufactured by first printing [...]
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Automated Manufacture of Grid Stiffened Panels
J. Müller, P. Nijhuis

I European Conference On Multifunctional Structures (EMuS 2019).

Abstract
Rib or grid stiffened structures have been investigated for decades, mainly for application in space structures. Grid structures offer the possibility to develop more damage tolerant structures as the network of ribs can provide redundant load paths. In an ideal situation, an aircraft fuselage could have a load carrying grid with ribs that carry tensile, compressive and shear loads. The skin would only need to sustain the cabin pressure load. Such a configuration could lead to significant weight reduction as a different design philosophy can be used. Typically, a damage tolerant design approach allowing a maximum of 3000 µstrain is used for composite aircraft structures. Using a grid structure, a different approach could be developed for a design which could allow strains up to 6000 µstrain. Automated fibre placement has made composite grid structures an affordable option. However, they pose a major challenge in the development of tooling for cure due to their complex and sometimes irregular structure. Within the European funded Horizon 2020 ACASIAS programme, square antenna elements are developed to be integrated in a composite aircraft fuselage panel. For this reason, an orthogrid stiffener pattern was chosen. As the skin of the panel must be transparent for the antenna signals, a glass fibre skin is required. A glass fibre skin to carry shear loads and carbon fibre ribs to carry compression and tension loads is therefore being developed to be able to meet structural and electromagnetic requirements. This paper describes aspects of the ongoing development for the design, manufacture and testing of an orthogrid stiffened structure in an efficient way. Simple alternating cutting of tapes at the crossing appear to be a suitable solution with a tensile stiffness reduction of 10 % compared to the situation without cuts. These and other details and elements are tested to validate the final design. The use of reusable silicone vacuum bags was investigated in order to replace complex metal tooling blocks. Besides saving on mould materials and machining, the use of a preshaped silicone vacuum bag is expected to reduce labour cost due to a decrease in handling of tooling blocks for positioning and cleaning. The first trial indicates that good quality laminates can be obtained using reusable vacuum bags. More testing will be carried out to validate the concept for a large 3×1.2 m panel.
Abstract
Rib or grid stiffened structures have been investigated for decades, mainly for application in space structures. Grid structures offer the possibility to develop more damage [...]
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Comparision of Density Measurement Methods for Unidirectional Flax-Epoxy Polymer Composites
Y. Saadati, J. Chatelain, G. Lebrun, Y. Beauchamp

I European Conference On Multifunctional Structures (EMuS 2019).

Abstract
Density is a decisive factor in determining one of the most important advantages of flax fiber-reinforced polymer (FFRP) composites, i.e. their relatively low weight leading to high specific properties. As a fundamental physical property of composites, density enters in many engineering design and quality control calculations and its value is a determining factor for several applications. Especially, we need precise material properties including density so as to develop efficient numerical models to these materials. In this work, three density measurement methods were evaluated and compared: Helium-gas pycnometry and Archimedes with two different immersing liquids, water and ethanol. The results show that Helium-gas pycnometry and Archimedes with ethanol gave similar and repeatable results, whereas using water resulted in much lower values. The density values were all in the range of reported values. However, Helium-gas pycnometry or Archimedes using ethanol are recommended for more precision in measuring the density of FFRP composites.
Abstract
Density is a decisive factor in determining one of the most important advantages of flax fiber-reinforced polymer (FFRP) composites, i.e. their relatively low weight leading [...]
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Contribution of Conformal Antennas Towards Sustainable Aircraft
P. Vrchota, A. Prachař, M. Šmíd, J. Middel

I European Conference On Multifunctional Structures (EMuS 2019).

Abstract
This paper shows the drag and emission reduction potential of integrated, flush communication antennas at the surface of an airliner. The CFD simulations of the aircraft model representing a modern airliner with radome in different locations on its upper part of the fuselage have been done. The results have been compared with the baseline configuration of the aircraft without radome. The aerodynamic equivalent weight penalty and additional fuel needed due to the drag of the radome and its weight itself have been calculated by two approaches. The obtained drag reduction potential has been used for the estimation of the CO2 and NOx emissions reduction by using integrated antenna.
Abstract
This paper shows the drag and emission reduction potential of integrated, flush communication antennas at the surface of an airliner. The CFD simulations of the aircraft model [...]
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Cooling of Active Components in Structurally Integrated Phased Arrays Antennas
J. Leiß, T. Ebert, M. Martínez-Vázquez, R. Baggen

I European Conference On Multifunctional Structures (EMuS 2019).

Abstract
This paper presents an innovative cooling solution for active phased array antennas, using a 3D printed liquid cooling device integrated in the structure’s PCB.
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Design Consideration for Fully Embedded Electronically Steerable SatCom Airborne Antenna
G. Expósito, J. Abellán, A. Jiménez, F. Martín, J. Menéndez, F. Cano, F. Jiménez, A. Gal

I European Conference On Multifunctional Structures (EMuS 2019).

Abstract
In this paper a conceptual design of a SATCOM On The Move (SOTM) system in the Ka band is presented. This system is intended to be airborne and fully integrated in an AIRBUS C295 Flight Test Bench. The system relies in two separated low profile TX and RX antennas (about half a meter size) which reach up to 10Mbps return link and 50Mbps forward link.
Abstract
In this paper a conceptual design of a SATCOM On The Move (SOTM) system in the Ka band is presented. This system is intended to be airborne and fully integrated in an AIRBUS [...]
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Development of Multifunctional Materials and Structures with Improved Capacities in Aerodynamics, De-icing, Acoustics or Electromagnetism for Civil and Military Aircrafts
B. Berton

I European Conference On Multifunctional Structures (EMuS 2019).

Abstract
For several years, either in the frame of research projects (French, European), or for direct application on aircraft programs, Dassault Aviation has developed multifunctional materials and structures (MMS) with specific benefits in aerodynamics, de-icing, acoustic or electromagnetisms. The main challenge is to get the best compromise between the high functional performances desired and the mechanical and aeronautic environment resistance needed for the application. This presentation will review some examples of development performed in the recent years for aircraft aerodynamics improvement, icing protection, acoustics and new antenna radomes.
Abstract
For several years, either in the frame of research projects (French, European), or for direct application on aircraft programs, Dassault Aviation has developed multifunctional [...]
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Electrical Conductivity and Electromagnetic Shielding Effectiveness of Bio-Composites
K. Tserpes, V. Tzatzadakis, J. Bachmann

I European Conference On Multifunctional Structures (EMuS 2019).

Abstract
In this paper, electrical conductivity and electromagnetic shielding effectiveness of two bio-composites have been studied by tests and numerical models. Two monolithic composites with partly bio-based content were manufactured. The first bio-composite is made of a carbon fibre fabric prepreg and a partly bio-based (rosin) epoxy resin (CF/Rosin). The second bio-composite is a combination of prepregs of carbon fibre fabric / epoxy resin and flax fibre fabric / epoxy resin (CF-Flax/Epoxy). A single line infusion process has been used prior to the curing step in the autoclave. Both variants are exemplary for the possibility of introducing bio-based materials in high performance CFRP. In-plane and out-of-plane electrical conductivity tests have been conducted according to Airbus standards AITM2 0064 and AITM2 0065, respectively. Electromagnetic shielding effectiveness tests have been conducted based on the standard ASTM D 4935-10. Materials were prepared at the German Aerospace Center (DLR) while characterization tests were conducted at the University of Patras. In addition to the tests, numerical models of representative volume elements have been developed using the DIGIMAT software to predict the electrical conductivity of the two bio-composites. The preliminary numerical results show a good agreement with the experimental results.
Abstract
In this paper, electrical conductivity and electromagnetic shielding effectiveness of two bio-composites have been studied by tests and numerical models. Two monolithic composites [...]
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Exploration of Radiating Aerostructures Ultimate Antenna and Structure Integration
Y. Konter, C. Heuts, C. Hengel

I European Conference On Multifunctional Structures (EMuS 2019).

Abstract
Two antenna designs are described that are both fully integrated into Fiber Metal Laminate fuselage panels. Full integration in this context means that the antennas are flush with the fuselage skin on the outside of the aero structure, while maintaining the structural properties of the FML panel. The antennas are designed to resonate at GNSS and at VHF frequency bands. Design considerations are discussed and preliminary results are presented.
Abstract
Two antenna designs are described that are both fully integrated into Fiber Metal Laminate fuselage panels. Full integration in this context means that the antennas are flush [...]
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From Design Towards Manufacturing of Winglets with Integrated VHF Antenna
K. Gonet, S. Steeger, Z. Řezníček, M. Martínez-Vázquez, J. Balcells-Ventura, P. Vrchota, V. Lungaho

I European Conference On Multifunctional Structures (EMuS 2019).

Abstract
This paper shows the technical aspects and the progress of manufacturing a winglet concept with integrated VHF antenna.
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Functionalization of Carbon Nanotubes and Mechanical Characterisation of Bio-based Epoxy Nano-composites
A. Singh, C. Sguazzo, C. Lima, L. Santos, P. Tavares, P. Moreira

I European Conference On Multifunctional Structures (EMuS 2019).

Abstract
Chemical functionalization of multiwalled carbon nanotubes (MWCNTs) is important from the view point of polymer based composite manufacturing. As pristine MWCNTs has certain disadvantage such as they have lower dispersion, they are hydrophobic and are not readily soluble in a solvent, these characteristics makes them unreliable candidate for most of the industrial applications. By doing chemical functionalization of MWCNTs, these shortcomings can be overcome, and the MWCNTs can be used as a filler in composite manufacturing. This has the advantage of better nanofillers’ dispersion and provide the better interfacial bonding. In this study, MWCNTs are functionalized by the carboxylic group, chemical functionalization of MWCNTs is an optimization problem, governed by parameters like mixture acid concentration, temperature, time of heating and amount of MWCNTs used. Material characterization of MWCNTs is done and test specimens are manufactured according to different concentrations of MWCNTs within a bio-based epoxy resin. Mechanical properties are then compared according to different concentrations. These mechanical and material characterizations increase the understanding of chemical functionalization by carboxylic group and the influence of the concentration of MWCNTs dispersed within the bio-based resin matrix.
Abstract
Chemical functionalization of multiwalled carbon nanotubes (MWCNTs) is important from the view point of polymer based composite manufacturing. As pristine MWCNTs has certain [...]
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Integrating Electromagnetic Functions into Fiber Metal Laminates – the Structural Challenge
C. Hengel, C. Heuts, J. Verpoorte

I European Conference On Multifunctional Structures (EMuS 2019).

Abstract
This paper outlines aspects, outcome and prospects of full integration of antennas into structural elements of aircraft, from a structural design perspective.
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Manufacturing Aspects of Active Acoustic Lining panel
K. Gonet, S. Steeger, S. Algermissen, V. Lungaho

I European Conference On Multifunctional Structures (EMuS 2019).

Abstract
This paper shows the technical aspects and the progress of manufacturing a lining concept with actuators and sensors for noise reduction within the cabin of aircraft with CROR engine. The structural integration, the repair possibilities and the serial production of such a lining are focused.
Abstract
This paper shows the technical aspects and the progress of manufacturing a lining concept with actuators and sensors for noise reduction within the cabin of aircraft with [...]
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New Enhanced Acoustic Damping Composite Material for the Aeronautics Industry
D. Pastorino, J. Lorenzo, B. López-Romano, P. Hadley, T. Blanco

I European Conference On Multifunctional Structures (EMuS 2019).

Abstract
The present article investigates an innovative structural composite material concept with the additional functionality of acoustic damping. It is achieved by introducing an embedded elastomeric layer within the composite laminate, which constitutes a constrained layer damping (CLD) system. The main objective is to increase the acoustic performance of the baseline material, while its mechanical properties are maintained. In addition, material processability and inspectability have been considered as important drivers for the technology development. In order to identify the most promising candidate, a set of alternatives has been explored and analysed, giving rise to a compromise solution between the enhanced acoustic performance and the structural properties of the baseline material.
Abstract
The present article investigates an innovative structural composite material concept with the additional functionality of acoustic damping. It is achieved by introducing an embedded [...]
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Remote Sensing for a Lining Integrated Active Structural Acoustic Control System
M. Misol, S. Algermissen

I European Conference On Multifunctional Structures (EMuS 2019).

Abstract
In the framework of the EU project ACASIAS an aircraft sidewall panel (lining) with structurally integrated actuators and sensors is developed. Each lining has a digital unit which samples the sensor signals, performs filtering operations and supplies the actuators with control signals. The whole system makes up an active structural acoustic control system aiming at the reduction of low-frequency multi-tonal aircraft interior noise. The novelty of this approach compared to past implementations of active noise control (ANC) systems in aircraft is its modularity. Each so-called smart lining is autonomous in the sense that it processes only structural sensor data from its own integrated sensors. The use of external microphones for error sensing is avoided because this conflicts with the modularity of the smart lining. Hence, one important design task is the replacement of the physical error microphones by the integrated structural sensors and an acoustic filter (observer) running on the digital unit. This method, which is called the remote microphone technique for active control, has never been applied to an aircraft interior structure so far. The detailed design of the smart lining module comprises several steps which are taken within work package 3 of the ACASIAS project. Experimental data of an aircraft typical double panel system is captured in a sound transmission loss facility. The system is excited with a loudspeaker array placed directly in front of the fuselage structure. Different acoustic load cases are used for the definition of the sensors and the actuators. A multi-tonal excitation with high sound pressure level is relevant for the actuator dimensioning and a broadband excitation with multiple independent sound sources is relevant for the sensor definition. 19 accelerometers are mounted on the lining and 20 microphones are placed in front of it. All sensor signals are sampled simultaneously for deterministic and broadband load cases. The lining is equipped with two inertial mass actuators which are used for the active control. Measured frequency response functions of actuators at 39 positions are used for the optimization of the actuator locations. The measurement data is also used for the derivation of an observer and for the simulation of a smart lining with remote microphones. In this contribution, the steps undertaken for the detailed design will be described and simulation results of the noise reduction performance of the smart lining with remote microphones will be presented.
Abstract
In the framework of the EU project ACASIAS an aircraft sidewall panel (lining) with structurally integrated actuators and sensors is developed. Each lining has a digital unit [...]
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Structural Analyses of Orthogrid Fuselage Panel for Integrated Ku-band SatCom Antenna.
F. Turon, F. Otero, X. Martinez

I European Conference On Multifunctional Structures (EMuS 2019).

Abstract
The aim of this work is to describe the structural analysis of a multifunctional aircraft fuselage panel. The structure of the panel has an embedded antenna tiles. The panel consists of UniDirectional (UD) carbon fibre reinforced composite skin stiffened with ortho-grid ribs, and a transparent skin window made using UD glass fibre reinforced composite. The orthogrid structure is a structural reinforcement but also the antenna tiles support. The presented work proposes a numerical multiscale strategy. The laminate is simulated with solid elements, in order to capture the real kinematics of the material, but several laminas are condensed in a single finite element. The performance of each lamina is obtained using the Serial-Parallel (SP) mixing theory. The specific formulations developed have been very useful to identify and study the mechanical performance of these new structures and the localization of unknown and un-predicted hot-spots in the structure.
Abstract
The aim of this work is to describe the structural analysis of a multifunctional aircraft fuselage panel. The structure of the panel has an embedded antenna tiles. The panel [...]
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Structural Integration of a Ku-band SatCom Antenna into Novel Fuselage Panel
J. Verpoorte, A. Hulzinga

I European Conference On Multifunctional Structures (EMuS 2019).

Abstract
This paper addresses the structural integration of a Ku-band SATCOM antenna in the fuselage of an aircraft. The phased array antenna consists of 25 antenna tiles that are integrated in an orthogrid fuselage panel. The specific electromagnetic aspects of the antenna integration will be discussed in this paper; this concerns the lightning protection of the antenna tiles and the electromagnetic interaction of the CFRP orthogrid and GFRP fuselage skin with the array antenna. The structural properties and thermal management of the antenna will be discussed in separate papers [1,2,3].
Abstract
This paper addresses the structural integration of a Ku-band SATCOM antenna in the fuselage of an aircraft. The phased array antenna consists of 25 antenna tiles that are integrated [...]
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Textile-Integrated Transmitting Unit
M. Cupal, J. Dřínovský, T. Götthans, J. Láčík, J. Prášek, Z. Raida, D. Kráčalová, Z. Ledrová, J. Procházka, D. Krutílek, Z. Řezníček

I European Conference On Multifunctional Structures (EMuS 2019).

Abstract
This contribution deals with the main parts of the textile-integrated transmitting unit, a transmitter and an antenna, operating in the ISM 5.8 GHz band. The transmitter is based on commercially available WLAN UART Serial Port OWS451 and it is controlled via the UART interface by microprocessor ATmega328. The antenna is based on the circular ring-slot concept and it is able to provide monopolar radiation pattern to ensure maximum coverage of the unit. The unit will be integrated in a seat cover and it will transmit the telemetry of sensors integrated in the seat (temperature, pressure…).
Abstract
This contribution deals with the main parts of the textile-integrated transmitting unit, a transmitter and an antenna, operating in the ISM 5.8 GHz band. The transmitter is based [...]
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The ECO-COMPASS EU-China Project
J. Bachmann, X. Yi

I European Conference On Multifunctional Structures (EMuS 2019).

Abstract
Fibre reinforced polymers are important materials used in aviation due to their excellent specific properties enabling the reduction of fuel consumption. For example, carbon fibre reinforced epoxy resins are used in fuselage and wing structures. Glass fibre reinforced phenolic resins are mainly used for the interior panels due to their low weight and favourable fire properties. All these composite materials used in aviation have one thing in common: they are man-made. Renewable materials like bio-fibres and bio-resins are under investigation for a long time for composites but they did not made it into modern aircraft in high amounts yet. The project ECO-COMPASS under Horizon 2020 aims to bundle the knowledge of 17 partners from China and Europe to develop ecological improved composites for the use in aircraft interior and secondary structures [1]. Bio-based reinforcements, epoxy resin and sandwich cores are developed and improved for their application in aviation. Furthermore the use of recycled carbon fibres to increase the mechanical strength and multifunctional aspects of bio-composites are evaluated. In order to withstand the special stresses in aviation environment, protection technologies to mitigate the risks of fire, lightning and moisture uptake are under investigation. An adapted modelling and simulation will enable the optimization of the composite design. Electrical conductive composites for electromagnetic interference shielding and lightning strike protection are under investigation in ECOCOMPASS as well. The cooperation includes the exchange of knowledge and materials in order to optimize the development of ecological friendly composites.
Abstract
Fibre reinforced polymers are important materials used in aviation due to their excellent specific properties enabling the reduction of fuel consumption. For example, carbon fibre [...]
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Towards a Lining Integrated Active Structural Acoustic Control System
S. Algermissen, M. Misol, A. Kokott, T. Haase, K. Gonet, V. Lungaho

I European Conference On Multifunctional Structures (EMuS 2019).

Abstract
For future aircraft counter-rotating open rotor (CROR) engines are a promising technology to reduce their CO2 footprint. Since the contribution of CROR engines to the cabin noise is higher than for jet engines, new strategies for the reduction of noise transmissions for frequency bands below 500 Hz are necessary. Active structural acoustic control (ASAC) systems are capable to reduce sound transmission of lining structures in this bandwidth. Sensors measure the vibrations of the lining to estimate its sound emission into the cabin. Based on these signals a controller calculates force signals for actuators on the lining. The actuator forces change the vibration behaviour of the lining in order to reduce its sound emission. For the realization of such a system in a real aircraft, manufacturing and maintenance issues have to be addressed. Within work package 3 of the EU project ACASIAS an aircraft lining with an integrated ASAC system is developed. The size of the lining is app. 1300 x 1690 mm2 (W x H) and it is simply curved. The radius of 2980 mm makes it relevant for a twin-aisle aircraft like the Airbus A350. The focus of research activities lies on the integration of components and the industrial manufacturing process of the lining. The components to be integrated are sensors, actuators and the corresponding wiring. A concept is proposed where each actuator and sensor is encapsulated in a kind of insert. The inserts smoothly integrate into the manufacturing process of the lining while they protect the actuators and sensors from humidity, dust, etc. The maintenance aspect is covered by the option to change each actuator or sensor upon insert level. The integrated wiring of the lining is left unaffected during an actuator or sensor replacement since connectors in each insert allow a nearly tool-free assembly/disassembly. In this paper the progress of work package 3 is presented at a detailed design review (DDR) stage. Finally, the lining will be manufactured and equipped with a full ASAC system. Experiments will be conducted in the acoustic transmission loss facility at the DLR.
Abstract
For future aircraft counter-rotating open rotor (CROR) engines are a promising technology to reduce their CO2 footprint. Since the contribution of CROR engines to the cabin [...]
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Martinez, Xavier 1995
International Centre for Numerical...

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Analysis of Radar Absorbing FSS on Foldcores and Honeycombs

Automated Manufacture of Grid Stiffened Panels

Comparision of Density Measurement Methods for Unidirectional Flax-Epoxy Polymer Composites

Contribution of Conformal Antennas Towards Sustainable Aircraft

Cooling of Active Components in Structurally Integrated Phased Arrays Antennas

Design Consideration for Fully Embedded Electronically Steerable SatCom Airborne Antenna

Development of Multifunctional Materials and Structures with Improved Capacities in Aerodynamics, De-icing, Acoustics or Electromagnetism for Civil and Military Aircrafts

Electrical Conductivity and Electromagnetic Shielding Effectiveness of Bio-Composites

Exploration of Radiating Aerostructures Ultimate Antenna and Structure Integration

From Design Towards Manufacturing of Winglets with Integrated VHF Antenna

Functionalization of Carbon Nanotubes and Mechanical Characterisation of Bio-based Epoxy Nano-composites

Integrating Electromagnetic Functions into Fiber Metal Laminates – the Structural Challenge

Manufacturing Aspects of Active Acoustic Lining panel

New Enhanced Acoustic Damping Composite Material for the Aeronautics Industry

Remote Sensing for a Lining Integrated Active Structural Acoustic Control System

Structural Analyses of Orthogrid Fuselage Panel for Integrated Ku-band SatCom Antenna.

Structural Integration of a Ku-band SatCom Antenna into Novel Fuselage Panel

Textile-Integrated Transmitting Unit

The ECO-COMPASS EU-China Project

Towards a Lining Integrated Active Structural Acoustic Control System

editors

Martinez, Xavier 1995

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