Advancement of Multifunctional support structure technologies (AMFSST)

The multifunctional support structure (MFSS) technology is promising a reduction of overall mass and packing volume for spacecraft (S/C) electronic components. This technology eliminates the electronic box chassis and the cabling between the boxes by integrating the electronics, thermal control and the structural support into one single element. The ultimate goal of the MFSS technology is to reduce size, weight, power consumption, cost and production time for future spacecraft components. The paper focus on the main challenges and solutions related to the thermal management within the MFSS technology based on the selected charge regulator (CR) application. Starting with the main set of thermal requirements for the CR the paper will include, conceptual and detailed design based on highconductivity carbon fibre CFRP, description and results of the thermal material sample test program ; parameter and results for the performed first thermal simulationComment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

IN-SERVICE INSPECTION OF AERONAUTICS PARTS PRODUCED BY ADDITIVE LAYER MANUFACTURING (ALM) - in the framework of Bionic Aircraft project (GA nº 690689)

Bionic Aircraft is a project founded under the H2020 Framework Program and it is a result of a need to reduce emissions due to the impact of the growth of the aviation industry. The introduction of Additive Laser Manufacturing (ALM) to produce some metal aircraft parts is considered as an opportunity to address this issue. This technology allows to produce ultra-lightweight and highly complex parts (so-called “bionic parts”). One of the actions to consider in the project is the development of new NDT strategies to inspect, in-service, parts produced by ALM made of Al-based alloys. This need arises because, ALM processes for these alloys are at low maturity level (TRL2) and hence, no proven and certified NDT methods are yet developed. Moreover, in-service inspection of aeronautic bionic parts involves challenges like the uncertainty of the inner inspection of a layered material, the lack of accessibility (the part is attached to the aircraft fuselage), and the expected defects under in-service conditions, something still under study. The objective of this work is to assess the inspection, in-service, of this kind of parts, by selecting and customizing the most suitable NDT methods, according to the type and maximum tolerable damage sizes estimated by a fatigue life prediction evaluation.H2020, 690689, Bionic Aircraf

RADIATION SHIELDING OF COMPOSITE SPACE ENCLOSURES

Space electronic systems employ enclosures to shield sensitive components from space radiation. The purpose of shielding is to attenuate the energy and the flux of ionizing radiation as they pass through the shield material, such that the energy per unit mass (or dose) absorbed in silicon is sufficiently below the maximum dose ratings of electronic components. The received radiation amount varies significantly depending on several variables that include mission parameters (orbit, altitude, inclination and duration), spacecraft design (spacecraft wall thickness and panel-enclosure location). To achieve the optimum shielding with the minimum weight, all these variables have to be considered in the design. Energetic particles, mainly electrons and protons, can destroy or cause malfunctions in spacecraft electronics. The standard practice in space hardware is the use of aluminium as both a radiation shield and structural enclosure. Composite structures show potential for significant mass savings. However, conventional graphite epoxy composites are not as efficient shielding materials as aluminium because of their lower density, that is, for the same mass, composites provide 30 to 40% less radiation attenuation than aluminium. A solution is to embed high density (atomic weight) material into the laminate. This material, typically metallic material, can be dispersed in the composite or used as layers in the laminate (foils). The main objective of the “Radiation Shielding of Composite Space Enclosures” (SIDER) project is the development of the technologies and tools required to obtain lightweight, safe, robust and reliable composite structures. Two different strategies are being analysed as alternatives for radiation shielding: and he incorporation of a high density material foil. This paper will present and analyse the radiation shielding obtained by the incorporation of nanomaterials in composite structures

Study of the failure of a duplex stainless steel valve

A study has been performed to determine the reason for the failure of a group of duplex stainless steel valves after 15 years in service. Chemical analysis did not agree with the required quality. Metallographic analysis revealed some small pits with corrosive products inside which were blamed to be the origin of long cracks and consequently of the failure. Pitting and cracks progressed along the ferrite-austenite interface where carbides and brittle phases are precipitated. This precipitation drags a significant content of chromium whose percentage in the surrounding matrix is depleted losing its pitting resistance being attacked by the circulating fluid. The use of a steel with higher pitting resistance and avoid working in the temperature range where both carbides and brittle phases are formed is recommended.Peer reviewe

Failure analysis of the end of a shaft of an engine

The aim of this paper is to analyse the root causes of the premature failure of the end of the shaft of an engine, which was theoretically manufactured using a C45 steel. This shaft presented a keyway which was damaged and repaired by welding, machining a new one in another zone of its periphery. Neither the carbon content nor the mechanical properties of the steel agreed with those specified in the purchase order, having strength significantly lower than the envisaged one. Examination of the fracture surface revealed that the origin of the failure was sited in one corner y of the first keyway which was incorrectly repaired. From this origin, cracking progressed by fatigue until the area which remained joined was not enough for bearing the applied loading, inducing the failure. The marked damage suffered by the fracture surface precluded evaluating the existing ratio between fatigue crack growth and final fracture and determining if the stress level was high. Observation of the metallographic samples confirmed the deficient union between the key used for repairing the previous damage and the shaft promoting a faster cracking. Consequently, the failure of the shaft was attributed to the sum of various factors (lack of strength, incorrect design and execution of the repair) which have promoted the failure.Peer reviewe

Hot stamping of aerospace aluminium alloys: Automotive technologies for the aeronautics industry

This paper proposes the use of the hot stamping process that provides ready to use parts for the obtention of aircraft components as an alternative manufacturing technology to e.g. machined parts. The development has been focused on the study of the high temperature formability of aluminium alloys. The feasibility of hot forming the AA2198 aluminium lithium alloy into complex shapes component has been studied. A wide experimental campaign has been carried out to set up the optimum hot stamping process parameters. In addition, forming trials with different geometries (omega and B-pillar shapes) have also been performed and, after the corresponding heat treatment, material properties have been recovered. Simulations of the hot stamping process have been carried out with Pamstamp® 2G software. These results have been correlated with the ones obtained in the experimental campaign. As a final step of the development, a demonstrator corresponding to a wing rib has been successfully manufactured. Characterization carried out to the prototype indicate specifications are fulfilled.The study presented in this paper was carried out in the frame of OUTCOME project within Airframe ITD of Clean Sky 2 Programme. The project received funding from the Clean Sky 2 Joint Undertaking (JU) under ITD Airframe Grant Agreement for Members. The JU received support from the European Union's Horizon 2020 (H2020) research and innovation programme and the Clean Sky 2 JU members other than the Union. The authors want to acknowledge Airbus Defence and Space S.A.U for providing the design of the developed prototype, Aernnova Aero- space S.A.U for OUTCOME project coordination and facilitator and fruitful technical discussions and RIB-ON Consortium for developing and building the die and final manufacturing of the wing rib

Failure analysis of two sets of aircraft blades

This paper analyses the failure of two blades, coming from different aircraft engines. The first one corresponds to the high pressure compressor manufactured in a 718 nickel base superalloy. The failure analysis carried out on this blade points towards foreign object damage (FOD). The second set belongs to the high pressure turbine of another engine. Scanning electron microscopy attributes the first fail to the premature failure by a thermo-mechanical fatigue mechanism of one blade with an inadequate microstructure. The remaining blades of this set, which possess a correct microstructure, failed due to the impacts of the debris generated by the fracture of the first one.Peer reviewe

Failure analysis of two sets of aircraft blades

This paper describes the methodology employed for the failure analysis of aircraft blades and its application to two premature failed sets. The first one corresponds to the high pressure compressor manufactured in a 718 nickel base superalloy. The failure analysis carried out on this blade points towards foreign object damage (FOD). The second set belongs to the high pressure turbine of another engine. Scanning electron microscopy attributes the first fail to the premature failure by a thermo-mechanical fatigue mechanism of one blade with an inadequate microstructure. The remaining blades of this set, which possess a correct microstructure, failed due to the impacts of the debris generated by the fracture of the first one.Peer reviewe

Failure analysis of a set of compressor blades

This paper analyses the root causes of the failure of a set of blades belonging to the high pressure compressor of an aircraft engine. All these blades were manufactured using a 718 nickel base alloy. The performed study consisted in a fractographic analysis by scanning electron microscopy and a microstructural study using both scanning and optical microscopy. Phases which were present in the fracture surfaces were identified by means of X-ray energy dispersive spectrometry. As a result of this labour the failure was attributed to the impact of sand and stones; that is the so-called foreign object damage mechanism.Peer reviewe

Effect of microstructure on fatigue behaviour of cast Al-7Si-Mg alloy

The fatigue behaviour of a cast Al-7Si-Mg alloy, conforming to A356, has been studied. Specimens of this material were tested in both the as cast condition and a solution treated and aged condition. It was observed that the size, number, and position of casting defects influenced the fatigue life very strongly. This marked effect nearly hides that of the heat treatment. Nevertheless, if the analysis is carried out considering only results obtained from sound specimens it is revealed that the heat treatment causes an improvement in the fatigue resistance of the alloy.Peer reviewe