Mechanical behaviour of pre-stressed spruce timber–timber 2.5-mm-step grooved connections under shearing tests

A smart shear connection system was tested in order to be used in manufactured elements of a lattice of wooden slats and a cross offset. This type of floor element can present advantages both in terms of weight and suitable insulating filler (Adalberth et al. 2001; Kawasaki and Kawai 2006; Kermani and Hairstans 2006; Dodoo et al. 2014). This connection is made to provide a substitute for a glue connection. The shear connection proposed is made by double-sided grooving timber interfaces to form a cross section. A specifically designed test assembly was constructed to measure and guarantee homogeneous contact pressure in interface test specimens. Shear test results are presented and compared in terms of capacity and stiffness with glue connections. The principal conclusions are as follows: the allowable shearing resistance of the grooved timber–timber joints can approximately reach the resistance of glued connections. The stiffness of the joints is improved by increasing the pre-stress applied for holding contact in the assembly. The grooved timber-to-timber joints exhibit non-linear behaviour which dominates the behaviour of the whole system. Therefore, the behaviour of a unit connection must be determined to obtain the mean load-carrying capacity and stiffness of a system with grooved connections

K44M ferritic stainless steel as possible interconnect material for SOFC stack operating at 600 °c: Characterization of the oxidation behaviour at early working stages

A commercial ferritic stainless steel (FSS) known as K44M (Type 444, according to ASTM A 240, DIN 1.4521 according to NF EN 10088-2) was aged in static air in two differing thicknesses (i.e. 1.5 and 0.4 mm) at a thermal cycle corresponding to the curing phase of an experimental glass used as sealing in solid oxide fuel cell (SOFC) stacks, and to an ageing process in air of 200 h at 600 °C. The characterization performed on the aged samples after the complete treatment and at each step of the thermal cycle allowed to investigate the scale formed depending on the temperature and to the thickness of the samples

« Retour vers le futur » de l'inox dans l'automobile

Cette présentation reprend le contenu d'une conférence donnée en décembre 2012 à l'INSA de Lyon pour célébrer les 100 ans de l'Inox. L'objectif est de balayer 20 ans de recherche en métallurgie des aciers inoxydables qui ont accompagné l'évolution de l'automobile, en particulier celle de la ligne d'échappement et de sa fonction en dépollution. Le titre faisait aussi référence au film « Retour vers le Futur »  et à la DeLorean conduite par les héros et qui reste le seul véhicule conçu et vendu dans les années 80 avec une carrosserie en inox. Une idée qui refait surface aujourd'hui pour des considérations d'allègement plutôt que d'esthétique. L'utilisation de l'acier inoxydable n'est pas récente et est souvent illustrée par la décoration automobile, une fonction esthétique exigeante où l'inox reste le matériau de référence. Aujourd'hui, l'essentiel de l'inox utilisé dans le véhicule se trouve dans l'échappement et l'environnement moteur. La ligne d'échappement s'est transformée et l'acier inoxydable s'est adapté aux contraintes des normes de dépollution et d'allègement, se traduisant par des condensats d'échappement de plus en plus acides, des températures plus hautes. En parallèle une augmentation des garanties fonctionnelles de la ligne d'échappement est régulièrement demandée. Les aciers inoxydables présentent aussi des propriétés mécaniques qui les placent aux niveaux des aciers THR tout en conservant un allongement supérieur. Actuellement un effort de recherche est entrepris pour incorporer de l'inox dans d'autres parties du véhicule en particulier la structure (caisse en blanc et pièce de châssis), le réservoir et la pile à combustible (notamment les plaques d'interconnexion du cœur de pile)

« Retour vers le futur » de l'inox dans l'automobile “Back to the future” of stainless steel in the automotive

Cette présentation reprend le contenu d'une conférence donnée en décembre 2012 à l'INSA de Lyon pour célébrer les 100 ans de l'Inox. L'objectif est de balayer 20 ans de recherche en métallurgie des aciers inoxydables qui ont accompagné l'évolution de l'automobile, en particulier celle de la ligne d'échappement et de sa fonction en dépollution. Le titre faisait aussi référence au film « Retour vers le Futur »  et à la DeLorean conduite par les héros et qui reste le seul véhicule conçu et vendu dans les années 80 avec une carrosserie en inox. Une idée qui refait surface aujourd'hui pour des considérations d'allègement plutôt que d'esthétique. L'utilisation de l'acier inoxydable n'est pas récente et est souvent illustrée par la décoration automobile, une fonction esthétique exigeante où l'inox reste le matériau de référence. Aujourd'hui, l'essentiel de l'inox utilisé dans le véhicule se trouve dans l'échappement et l'environnement moteur. La ligne d'échappement s'est transformée et l'acier inoxydable s'est adapté aux contraintes des normes de dépollution et d'allègement, se traduisant par des condensats d'échappement de plus en plus acides, des températures plus hautes. En parallèle une augmentation des garanties fonctionnelles de la ligne d'échappement est régulièrement demandée. Les aciers inoxydables présentent aussi des propriétés mécaniques qui les placent aux niveaux des aciers THR tout en conservant un allongement supérieur. Actuellement un effort de recherche est entrepris pour incorporer de l'inox dans d'autres parties du véhicule en particulier la structure (caisse en blanc et pièce de châssis), le réservoir et la pile à combustible (notamment les plaques d'interconnexion du cœur de pile). The use of stainless steel in automotive is not really new and began with the decorative trims because of its unique brightness and anticorrosion properties. Today, most of the stainless steel parts in vehicle are situated in the exhaust and powertrain systems. In fact, the exhaust line is subjected to a continuous evolution due to the more and more severe emissions regulations. Consequences are more acidic condensates, higher temperatures, and new high temperature corrosion-fatigue mechanisms that lead to the requirement of more and more resistant stainless steels to guaranty longer component's lifetime. The stainless steels could also exhibit interesting and very high mechanical properties at the level of AHSS carbon steels but preserving their excellent elongation and structural applications could be also prospected. Therefore research efforts are currently attempted to introduce stainless steel in body-in-white or chassis parts, but also in bio-fuel tank components, battery and for the future, in fuel cells propulsion. This paper is the summary of a talk at INSA Lyon in December 2012 to celebrate the century of the stainless steel. Its objective is to deal with the research progress made to adapt the stainless steel family to the transformation of the automotive for 20 years

Dual atmosphere study of the K41X stainless steel for interconnect application in high temperature water vapour electrolysis

High temperature water vapour electrolysis (HTE) is one of the most efficient technologies for mass hydrogen production. A major technical difficulty related to high temperature water vapour electrolysis is the development of interconnects working efficiently for a long period. Working temperature of 800 °C enables the use of metallic materials as interconnects. High temperature corrosion behaviour and electrical conductivity of a commercial stainless steel, K41X (AISI 441), were tested in HTE dual atmosphere (95%O2-5%H20/10%H2-90%H2O) at 800 °C. The alloy exhibits a very good oxidation resistance compared to single atmosphere tests. However, a supplied electrical current significantly changes the nature of the oxides that form during the test. A very good Area Specific Resistance (ASR) parameter was measured in dual atmosphere, much lower than the values obtained in single atmosphere tests

kinetic model of the glycerol oxidation by using a silver-based catalyst

SSCI-VIDE+CDFA+DLJ:PFOInternational audienceThe depletion of fossil fuels has led to the development of alternative and environmentally-friendly energy carriers, such as biodiesel. The manufacture of biodiesel leads to glycerol (GLY) as the main by-product (10 wt.%), so that its valorization has become an important issue. GLY is a versatile polyol which can be used as a bio-building block of different add-value products.There are many GLY transformation pathways, and among them the oxidation in the liquid phase has gained a great interest. So far, Pt, Pd and Au have been used as active phases in this reaction. These metals are selective towards the formation of glyceric acid in basic media. On the other hand, the use of Ag in this reaction has been seldom studied. This metal has been proven to be selective to glycolic acid [1], which is used in food, cosmetics and textile industries.The aim of this work is to develop a kinetic model of the GLY oxidation in the liquid phase, by using the experimental results obtained with an Ag/CeO2 catalyst. The effect of the reaction temperature and NaOH concentration was taken into account. Moreover, experimental results revealed that the catalyst was somehow deactivated, so that thedeactivation kinetics has also been included in the proposed model.First of all, the reaction pathways were deduced from the experimental data. Only glyceric, glycolic and formic acid were observed as primary products, as observed in Figure 1. A power-law kinetic model was proposed, by considering first order reaction of all components and a carbon balance close to 100%. Deactivation kinetics was considered first-order ofactivity and zero-order of the species concentration. Parameter fitting was carried out by using Matlab.The parity plot and results of the parameter fitting, (Figure 2), revealed that the proposed kinetic model predicted well the experimental concentrations, whereas the fitted parameters were statistically significant. The obtained activation energies were practically the same for all reactions. However, reaction 2 displayed the highest k value at the referencetemperature, which confirmed the high selectivity of the Ag-based catalyst towards glycolic and formic acids. As for deactivation kinetic parameters, results revealed that the catalyst deactivation was significant, whereas the high activation energy suggested a strong dependence on the reaction temperature. Future work will be focused on two points: to develop a heterogeneous Langmuir-Hinshelwood model and to compare different deactivation kinetics.This work has been performed, in partnership with the SAS PIVERT, within the frame of the French Institute for the Energy Transition (Institut pour la Transition Energétique (ITE) P.I.V.E.R.T. www.institut-pivert.com) selected as an Investments for the Future (âInvestissements dâAvenirâ). This work was supported, as part of the Investments for the Future, by the French Government under the reference ANR-001-01

Kinetic modelling of the glycerol oxidation in the liquid phase: comparison of Pt, Au and Ag AS active phases

SSCI-VIDE+CDFA+DLJ:PFOInternational audienceglycerol oxidatio

Promising Stability of Gold-Based Catalysts Prepared by Direct Anionic Exchange for DeNO x Applications in Lean Burn Conditions

International audienc