Development of a multifunctional panel for aerospace use through SLM additive manufacturing

Lattice materials can overcome the need of light and stiff structures in the aerospace industry. The wing leading edge is one of the most critical parts for both on-board subsystem and structure features: it must withstand to the aerodynamic loads and bird-strike, integrating also the anti-ice system functions. Nowadays, this part is made by different components bonded together such as external skin, internal passageways, and feeding tubes. In the present work, a single-piece multifunctional panel made by additive manufacturing will be developed. Optimal design and manufacturing are discussed according to technological constraints, aeronautical performances and sustainability

Spin-Coated vs. Electrodeposited Mn Oxide Films as Water Oxidation Catalysts

Manganese oxides (MnOx), being active, inexpensive and low-toxicity materials, are considered promising water oxidation catalysts (WOCs). This work reports the preparation and the physico-chemical and electrochemical characterization of spin-coated (SC) films of commercial Mn2O3, Mn3O4 and MnO2 powders. Spin coating consists of few preparation steps and employs green chemicals (i.e., ethanol, acetic acid, polyethylene oxide and water). To the best of our knowledge, this is the first time SC has been used for the preparation of stable powder-based WOCs electrodes. For comparison, MnOx films were also prepared by means of lectrodeposition (ED) and tested under the same conditions, at neutral pH. Particular interest was given to -Mn2O3-based films, since Mn (III) species play a crucial role in the electrocatalytic oxidation of water. To this end, MnO2-based SC and ED films were calcined at 500 C, in order to obtain the desired -Mn2O3 crystalline phase. Electrochemical impedance spectroscopy (EIS) measurements were performed to study both electrode charge transport properties and electrode-electrolyte charge transfer kinetics. Long-term stability tests and oxygen/hydrogen evolution measurements were also made on the highest-performing samples and their faradaic efficiencies were quantified, with results higher than 95% for the Mn2O3 SC film, finally showing that the SC technique proposed here is a simple and reliable method to study the electrocatalytic behavior of pre-synthesized WOCs powders

Spin-Coated vs. Electrodeposited Mn Oxide Films as Water Oxidation Catalysts

Manganese oxides (MnOx), being active, inexpensive and low-toxicity materials, are considered promising water oxidation catalysts (WOCs). This work reports the preparation and the physico-chemical and electrochemical characterization of spin-coated (SC) films of commercial Mn2O3, Mn3O4 and MnO2 powders. Spin coating consists of few preparation steps and employs green chemicals (i.e., ethanol, acetic acid, polyethylene oxide and water). To the best of our knowledge, this is the first time SC has been used for the preparation of stable powder-based WOCs electrodes. For comparison, MnOx films were also prepared by means of lectrodeposition (ED) and tested under the same conditions, at neutral pH. Particular interest was given to -Mn2O3-based films, since Mn (III) species play a crucial role in the electrocatalytic oxidation of water. To this end, MnO2-based SC and ED films were calcined at 500 C, in order to obtain the desired -Mn2O3 crystalline phase. Electrochemical impedance spectroscopy (EIS) measurements were performed to study both electrode charge transport properties and electrode–electrolyte charge transfer kinetics. Long-term stability tests and oxygen/hydrogen evolution measurements were also made on the highest-performing samples and their faradaic efficiencies were quantified, with results higher than 95% for the Mn2O3 SC film, finally showing that the SC technique proposed here is a simple and reliable method to study the electrocatalytic behavior of pre-synthesized WOCs powders

Sandwich panel with lattice core for aircraft anti-ice system made by Selective Laser Melting

Additive Manufacturing (AM) technology offers the possibility to build strong and light components with complex structures, as lattice, optimizing the strength/mass ratio. The goal of this work is the characterization of an innovative sandwich panel with trabecular core made by Selective Laser Melting (SLM), used as heat exchanger for many industrial applications, for example in aerospace field [1]. In this case study, the panel is integrated into the leading edges of aircraft wings and acts as hot air anti-icing system and, at the same time, as impact absorber (Figure 1). The system, due to its lightness and shape, leads to the optimization of the heat exchange, the improvement of the thermal efficiency, and the reduction of fuel use and gas emission. A set of experimental and numerical tests is conducted on lattice specimens through a Design of Experiment (DOE). Different design parameters were varied to understand how they affect the mechanical and thermal behavior: six different cell shapes (Figure 2), varying cell size and volume fraction, were tested. The same experimental program is carried out for two different metal alloys: AlSi10Mg and Ti6Al4V. Mechanical tests involve compression test on single core and on the whole panel, flexural and impact test. Further analisys on failure mechanism is carried out by observation with Optical Microscope. Thermal behavior of the system is also investigated by preliminary thermal simulations, whose results are validated by experimental measuraments of the temperature gradients on the external surface. [1] C. Ferro et al., Technologies, 2017, 5, 35; doi:10.3390/technologies502003

Study and development of an innovative L-PBF demonstrator and an anti-ice solution based on trabecular structures

L'abstract è presente nell'allegato / the abstract is in the attachmen

Lattice structured impact absorber with embedded anti-icing system for aircraft wings fabricated with additive SLM process

This paper introduces the design and preliminary characterization of modified lightweight panel for aircraft wings produced by additive manufacturing (AM) technology. The benefits of the innovative structure are described in terms of improved strength and systems functions and reduction of overall weight and operative costs

AEROMOBILE DOTATO DI SISTEMA ANTIGHIACCIO STRUTTURALMENTE INTEGRATO

Il sistema brevettato riguarda un anti ghiaccio termico, ma supera lo stato dell'arte introducendo dei vantaggi quali: • unico componente che integra sia la parte strutturale del pannello del bordo d'attacco che quella sistemistica/termica relativa all'anti-ghiaccio, come si può vedere dalla Fig.3; • semplificazione impiantistica; • migliore efficienza di scambio termico; • riduzione dei tempi di assemblaggio e degli oneri di manutenzione. Utilizzando un pannello sandwich con un nucleo trabecolare che integra, nella sua faccia interna, i tubi di apporto di aria calda, infatti, è possibile sia massimizzare lo scambio termico (aumentando esponenzialmente la superfice esposta grazie alle trabecole e la turbolenza interna) che la riduzione delle ore di assemblaggio e di manutenzione semplificando i controlli periodici. La struttura così proposta si intende realizzata mediante la tecnologia di fabbricazione additiva di tipo "Powder Bed" che permette di costruire insieme sia il core trabecolare che le skin e relativi i tubi in un unico componente, senza quindi dover ricorrere a saldature, brasature o rivettature. Un altro vantaggio, di tipo strutturale è da ricercarsi nella aumentata rigidezza al birdstrike avendo inserito dei tubi internamente che fungono da correntini, aumentando la rigidezza meccanica. Non ultimo, la migliorata fluidodinamica interna, grazie alle trabecole e alla dislocazione multipla dei tubi, permette non solo di massimizzare lo scambio di energia (e quindi di spillare meno aria dai compressori), ma anche di riscaldare selettivamente solo la sezione relativa alla zona di formazione di ghiaccio, con una minore dispersione termica che comporta un notevole risparmio negli spillamenti e, quindi, una riduzione dei consumi

Mechanical behaviour of a multifunctional panel for de-icing systems

Anti-ice and De-ice are critical systems on modern airplanes. The potential hazards caused by the formation of ice on the external surfaces are various: from the loss of important flight data (such as flight speed and altitude) with the icing of air probes to more severe hazards such as the locking of the movable surfaces or also increase of drag due to the changing of the aerodynamic profile. To face this problem during the years different techniques have been adopted. One of the first solution was to add on the leading edges of the wing polymeric tubes to inflate with pneumatic air source; in this manner, the ice attached to the wing is removed mechanically. Other system uses different sources such as chemical sources (glycol) but are not suitable for large aircrafts. The most diffused plant takes hot air from the engines compressor and heat the sandwich panels of the wing blowing from the inner skin. This system requires feeding tubes (generally made of aluminium), valves and complex passageways to enhance the specific heat exchange surface. The proposed solution overcomes this adding of weight introducing a single sandwich panel with a porous cellular core, that have both structural and thermal functions. This device integrates, in a single component, the passageways of the hot air and the structure of the leading edges, without welding or bonding, due to the use of Additive Manufacturing (AM). In fact, this technique allows the production of complex geometries without additional costs. Moreover, it promotes the realization of components with a great by to fly ratio due to less use of material. Selective Laser Melting (SLM) is a Powder Bed Deposition AM technology: a technique that selectively melt the powders, deposited in layers, according with STereo Lithography interface format (STL) data provided. Layers by layers the component is produced and finally extracted from the machine, separating it from the un-melted powders that can be reused. The realization of a sandwich panel with a core in trabecular structure fully exploits the potential of the technology: as said before these structures are necessary to ensure a great heat exchange between the anti-icing panel material and the hot air tapped from the engine. To further improve the efficiency of the device, a material with a great thermal conductivity, like aluminium alloys, is chosen. In particular, the components are produced with AlSi10Mg powders, a traditional casting alloy, for which the SLM machine parameters are already been optimized. AM technology allows the production of sandwich panels with a very different structure in respect to the traditional one type actually used in aerospace industry: the component is made in only one material and in one piece, without welding and polymeric bonding. It a beneficial point for both the thermo-mechanical behaviour and the final weight of the device. The present work exploits the mechanical behaviour of this porous core sandwich with a comparison between experimental results collected from experimental characterization with numerical analysis based on a dedicated finite elements model. In particular, compressive tests will be presented for the porous core together with three points bending on the complete sandwich panel