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In order to obtain a widespread application of Additive Manufactured (AM) technology in the aircraft industry for fatigue critical parts, a detailed characterization of the Fatigue and Damage Tolerance (F&DT) behavior of structural components is required. Metal AM techniques in particular are prone to internal defects inherently present due to the nature of the process, which have a detrimental effect on fatigue properties. In the present work, Ti6Al4V and Inconel 718 coupons with artificially induced defects of different dimensions were produced by the Laser Powder Bed Fusion (LPBF) technique. Fatigue tests were performed, and a different defect sensitiveness was observed between the two materials with Inconel being more defect tolerant compared to Titanium. The environmental role at the crack tip of internal defects was discussed, and based on a purely fracture mechanics approach, a simplified stress–life–defect size model was finally devised. The experimental test results together with the information obtained from the fracture surface analysis of tested samples are used to validate the model predictions. The proposed approach could be adopted to define a critical defect size map to be used for tailored Non-Destructive Testing (NDT) evaluation.

In order to obtain a widespread application of Additive Manufactured (AM) technology in the aircraft industry for fatigue critical parts, a detailed characterization of the Fatigue and Damage Tolerance (FDT) behavior of structural components is required. Metal AM techniques in particular are prone to internal defects inherently present due to the nature of the process, which have a detrimental effect on fatigue properties. In the present work, Ti6Al4V and Inconel 718 coupons with artificially induced defects of different dimensions were produced by the Laser Powder Bed Fusion (LPBF) technique. Fatigue tests were performed, and a different defect sensitiveness was observed between the two materials with Inconel being more defect tolerant compared to Titanium. The environmental role at the crack tip of internal defects was discussed, and based on a purely fracture mechanics approach, a simplified stress-life-defect size model was finally devised. The experimental test results together with the information obtained from the fracture surface analysis of tested samples are used to validate the model predictions. The proposed approach could be adopted to define a critical defect size map to be used for tailored Non-Destructive Testing (NDT) evaluation.

International audience; The aircraft industry is always looking for improved efficiency through higher in-service engine temperatures and lighter structures. Titanium-based alloys are good candidates for such applications because of their high specific strength. However, when exposed to high-temperature oxidizing environments, a large amount of dissolved oxygen can be found in such alloys beneath the growing oxide scale, possibly leading to embrittlement. Consequently, evaluating the oxidation resistance of these alloys is essential. With this aim, long-term oxidation tests were carried out on Ti6242S alloy between 500 and 650 °C to study the effect of temperature, surface preparation and microstructure on oxide scale and oxygen dissolution. While increasing the temperature from 560 to 625 °C led to accelerated oxidation kinetics, surface preparation had no noticeable effect on mass variations and oxygen diffusion profiles. Regarding microstructure, when comparing Ti6242S samples having similar α-phase fraction but very different microstructures (fineness and morphology), there wasn’t any significant effect found on mass change and oxygen diffusion after 1 kh at 650 °C.

Electron Beam Additive Manufacturing (EBAM) is a Wire Directed Energy Deposition (W-DED) process that is receiving much more attention than other Additive Manufacturing (AM) techniques, especially in the aeronautical sector for the serial production of metallic parts. However, this technique leads to singular microstructures due to the rapid heating and cooling cycles generated during the deposition of the pieces. In this work, a first identification of the main microstructural features of Ti-6Al-4V parts manufactured by EBAM technology is performed to better understand the general characteristics of this type of parts for further improvement of this technology. The characterization is carried out by means of Optical Microscopy (OM), Scanning Electron Microscopy (SEM) observations, and Energy Dispersive X-Ray Spectrometry (EDS) analysis. The most remarkable aspects found are the formation of long columnar prior beta grains throughout several layers in the built material and the presence of many parallel thermal bands perpendicular to the thermal gradient. Quantitative measurements such as the average width of the α lamellae, the volume fraction of β phase, and the chemical composition at different positions are also accomplished. A heterogeneous microstructure is reported, which mainly derives from the complex and diverse thermal histories at the different positions of the deposited material. In addition, Al vaporisation is noticed. However, no significant change along the deposit material is observed for a same configuration. Next, experiments will focus on the influence of different key processing parameters on the microstructure and mechanical properties.

Les phototraumatismes oculaires sont des lesions traumatiques d´origine photochimique. Elles sont responsables de lesions retiniennes ou maculaires qui peuvent etre graves et irreversibles. Nous rapportons le cas d´un patient de 35 ans de sexe masculin, sans antecedent particulier, recu pour une baisse de l´acuite visuelle de survenue brutale aux deux yeux a la suite de l´observation du soleil lors d´une seance de priere appele « danse du soleil ». L´effet deletere des rayons solaires sur les structures du globe oculaire a ete decrit depuis l´antiquite. L´avenement de la tomographie en coherence optique (OCT) a permis une meilleure approche des lesions maculaires solaires. Les phototraumatismes sont des lesions de gravite diverses qui generalement sont evitables par la sensibilisation.

Objective: Cataract is a partial or total opacification of the lens responsible for blindness. The treatment is surgical. The purpose of our study was to evaluate the results of the newly introduced manual small incision cataract surgery (SICS) and compare them with those of the conventional extra-capsular extraction method. Patients and Method: Analytical cross-sectional study was carried out at the ophthalmology department of the University Hospital of Bouake for a period of 1 year. Results: The two surgical techniques were compared at equal proportions. The average duration of interventions was longer during the sutured Extra Capsular Extraction (ECE) compared to the SICS. Rupture of the posterior capsule with vitreous exit, which was the most observed intraoperative complication, was predominant with ECE with suture (16%) against 8% for SICS. Corneal edema observed in the early postoperative period, was predominant with sutured ECE (30%), against 20% for SICS. Corneal edema, which was more observed with EEC compared to SICS, dominated secondary and late postoperative complications. Post-operative astigmatism induced by ECE with suture was between ?2 and ?4 dioptre in 51.5% of patients and between ?0.5 and ?2 dioptre in 73.91% of SICS. Visual acuity without correction in the early days was better with SICS. Conclusion: In this comparative study of cataract surgery, we noted superimposable results for both techniques. However, the prevalence of pre- and post-operative complications was more frequent with sutured ECE. The technique without suture allows visual recovery and a quick return to normal life.

Objective: To describe the epidemiological profile and indications of mutilating eyeball surgery in Abidjan. Patients and methods: This is a retrospective descriptive study on the files of eviscerated, enucleated or exentered patients in the Ophthalmology Department of the University Hospital of Yopougon from January 2010 to December 2016. The parameters studied were: socio-demographic characteristics, indications of mutilating surgery, anesthetic technique, operative technique and patient evolution. Results: During the study period, 59 patients underwent surgery for mutilating eye surgery out of a total of 11,114 procedures, a frequency of 0.53%. The average age of the patients was 31 years with extremes of 3 years and 67 years. Men predominated in 62.1% of cases with a sex ratio of 1.64. Patients came from rural areas in 68.5% of cases. The main indications of the mutilating surgery were: post-inflammatory phthisis (58.6%) and tumoral affections (29.31%). Evisceration was the most common operative technique (67.2%). In 68% of cases the interventions were performed under peribulbar anesthesia. Patients with evisceration (67.2%) and enucleation (5.1%) all benefited from prosthetic equipment. Conclusion: The mutilating surgery of the eyeball is responsible for serious psychological and sociological impacts. The seriousness of these repercussions requires primary prevention through early and adequate management of eye conditions.

Aircraft industry always looks for higher in-service temperatures and lighter structures. With a high specific strength, Ti-based alloys are good candidates for such applications. However, when exposed to oxidizing environments at high temperatures, they undergo large oxygen dissolution while forming an oxide scale, which can greatly affect their mechanical properties. Then, evaluating the oxidation resistance and mechanical behavior of such alloys is essential. In this aim, long term oxidation tests were performed under laboratory air between 500 °C and 625 °C on two Ti-based alloys: β21s, exhibiting a fully β microstructure supposed to dissolve lower amount of oxygen and nitrogen, and Ti6242S, with an α/β microstructure. The oxidized samples were characterized using XRD, Raman spectroscopy, SEM-EDS and micro-durometer. As for the mechanical behavior, tensile tests were performed at room temperature on not aged and on oxidized samples. While larger mass variations were obtained at 500 and 560 °C and up to 997 h at 625 °C for β21s, its mass variations became lower than those of Ti6242S for longer durations at 625 °C. Nevertheless, β21s exhibited thicker micro-hardness affected depths and underwent larger mechanical property modifications compared to Ti6242S.

Additive Manufacturing (AM) is rapidly expanding in aviation due to the advantages it offers compared to conventional manufacturing routes. It allows the production of geometry optimized complex parts with an efficient use of material. However, in order to design reliable parts using this novel manufacturing route, the changes it involves in material properties, defects and shape of parts need to be understood. This paper presents an industrial structural analysis approach applied by AIRBUS to justify newly introduced AM parts on aircraft. Some areas for future development and improvement are also presented.

International audience; Intradermal (ID) vaccination constitutes a promising approach to induce anti-infectious immunity. This route of immunization has mostly been studied with influenza split-virion vaccines. However, the efficacy of ID vaccination for sub-unit vaccines in relation to underlying skin innate immunity remains to be explored for wider application in humans. Relevant animal models that more closely mimic human skin immunity than the widely used mouse models are therefore necessary. Here, we show in domestic swine, which shares striking anatomic and functional properties with human skin, that a single ID delivery of pseudorabies virus (PRV) glycoproteins without added adjuvant is sufficient to trigger adaptive cellular and humoral immune responses, and to confer protection from a lethal respiratory infection with PRV. Analysis of early events at the skin injection site revealed up-regulation of pro-inflammatory cytokine and chemokine genes, recruitment of neutrophils and monocytes and accumulation of inflammatory DC. We further show that the sustained induction of pro-inflammatory cytokine genes results from the combined effects of skin puncture, liquid injection in the dermis and viral antigens. These data highlight that immune protection against respiratory infection can be induced by ID vaccination with a subunit vaccine and reveal that adjuvant requirements are circumvented by the mechanical and antigenic stress caused by ID injection, which triggers innate immunity and mobilization of inflammatory DC at the immunization site. ID vaccination with sub-unit vaccines may thus represent a safe and efficient solution for protection against respiratory infections in swine and possibly also in humans, given the similarity of skin structure and function in both species.

International audience; Titanium-based alloys are increasingly used in aircraft industry due to their good mechanical properties and low density. To reach better efficiencies, the engine design is constantly evolving and the temperature of the combustion chamber is always increasing. Then, surrounding parts are exposed to higher working temperatures and consequently have to cope with more severe oxidation phenomena. For Ti-based alloys, this leads to the formation of an external oxide scale and a large oxygen dissolution in the metal, which may be detrimental for ductility. As nitrogen is the major element of the atmosphere, it seems relevant to study its effect on the oxidation behavior of Ti-6Al-2Sn-4Zr-2Mo-0.1Si titaniumbased alloy used for these applications. Thermogravimetric analyses were carried out at 650 °C for 100 h in synthetic air (20%O2–80%N2) and in a mixture of 20%O2–80%Ar. Results showed that nitrogen decreases the oxidation kinetics by slowing down the oxide scale growth but also by limiting the oxygen dissolution inthe alloy.

At high temperatures under oxidizing environments, titanium-based alloys form an oxide scale and dissolve large amount of oxygen in their metallic matrix. Oxygen dissolution is a cause of embrittlement. Nitrogen is a secondary oxidant, which also dissolves in titanium during oxidation in air. Oxidation experiments of Ti-6Al-2Sn-4Zr-2Mo-0.1Si titanium-based alloy at 650 °C for 1000 h in synthetic air (20%O2- 80%N2) and in a mixture of 20%O2-80%Ar, showed that nitrogen reduces both oxide scale growth and oxygen dissolution. Atom probe tomography revealed that nitrogen effect is due to the formation of an interfacial layer of nitride Ti2N but also to the formation of a nitrogen rich a-Ti-based solid solution, which both act as difiusion barriers for oxygen because of their low oxygen solubility.

Colloque avec actes et comité de lecture. Internationale.; International audience; Les alliages de titane sont utilisés dans les composants aéronautiques tels que les structures secondaires de fixation du moteur. Augmenter l''efficacité du moteur conduit à une augmentation de la température de ces composants. Pour améliorer l'évaluation de la durée de vie de ces pièces, il est nécessaire d'obtenir une meilleure compréhension des changements en service, dans le comportement mécanique. Ceux-ci sont dus à l'enrichissement en oxygène de l'alliage pendant son oxydation. Dans ce travail, des échantillons minces en alliage Ti-6Al-2Sn-4Zr-2Mo-0.1Si ont été pré-oxydés pendant des durées contrôlées afin d'obtenir différentes épaisseurs de la couche affectée par l'oxygène. L'analyse par résonance acoustique permet d'obtenir le module de Young à différentes températures, des essais de traction et de fluage sont ensuite réalisés. En utilisant des échantillons minces, l'effet de la zone de diffusion de l'oxygène (ODZ) sur les propriétés mécaniques a été déterminé.