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Experimental Investigation on the Significance of the Conventional Endurance Limit of a Spheroidal Graphite Cast Iron
Full text linkFatigue tests were performed on a spheroidal graphite cast iron in four point plane bending under constant stress amplitude and block loading conditions. The microstructure of this material has a ‘bull’s eyes’ appearance, i.e. the spheroids of graphite are surrounded by ferrite and these nodules and ferrite zones are included in a pearlitic matrix. Scanning electronic microscope observations were carried out at different fractions of life for constant stress amplitude loadings above and below the conventional endurance limit. Non-propagating micro-cracks were observed at a stress level equal to the conventional endurance limit. These observations showed that another limit can be defined below the conventional endurance one, i.e. one below which micro-cracks were not observed to initiate in the matrix. These cracks were found to arrest at the ferrite/pearlite interface when the material was tested below this new limit. This concept was used to rationalize fatigue results from tests with loading in blocks above and below the conventional endurance limit
An energy based criterion for high cycle multiaxial fatigue
Full text linkIn spite of the great number of high cycle multiaxial fatigue in the literature, none predicts the difference that exist between the endurance limits in tension, four point rotative bending and four point plane bending. An enerdy based criterion based on a new concept using the strain energy density is proposed in the paper. This new calculation method explains the previous differnces by taking into account the volumic distribution of the strain energy density around the considered critical point in fatigue. This method, available now under fully reversed mutiaxial loadings, also takes into account the stress state triaxiality. Under combined plane bending and torsion the predictions of the new proposal lead to Gough and Pollard's ellipse quadrant for ductile materials and lead to a curve close to an ellipse arc for brittle materials. Under other multiaxial loadings, predictions are always close to an ellipse quadrant dependent on the loading mode. This method has been tested on smooth cylindrical specimens with several materials; calculations are in very good agreements with multiaxial experimental data
Physical and chemical characterization of automotive shredder residues
Full text linkCar manufacturers recycle many of the materials from wrecked vehicles, but the disposal of the lighter components is increasingly difficult. The high cost of landfill is making the option of incineration more attractive, as it reduces the mass and the volume of the waste. Energy recovery is also possible. This paper examines those properties of automotive shredder residues (ASR) which are relevant to the formation of pollutants during incineration. The higher specific energy of ASR was found to be 19,000 kJ kg-1 and the ash content 38%, which indicate that it is a suitable fuel for municipal incinerators or cement kilns. However, it is very heterogeneous, as the low density fraction is mainly composed of plastics, with smaller amounts of metallic pieces, rubber, glass and wood. The macroscopic composition of a representative sample of ASR was determined. The metal and the chlorine contents were analysed by special techniques and were found to be 22% and 3.5%, respectively of the fraction. Laboratory-scale incineration trials of ASR are now planned.ADEME RENAULT S
Identification of the environmental hotspots of a recycling process - Case study of a Pt PEMFC catalyst closed-loop recycling system evaluated via life cycle assessment methodology
Full text linkProton-exchange membrane fuel cell (PEMFC) technology using green H2 as a fuel to produce decarbonized electricity is considered as a promising substitute for fossil fuels. However, its development is impeded by the use of critical raw materials, such as platinum which catalyzes the hydrogen oxidation and oxygen reduction reactions. In this paper, a novel closed-loop system for the re-manufacturing of platinum-based catalyst electrode from recycled material is developed. Three different recycling alternatives are compared using the life cycle assessment (LCA) methodology. The most promising one, which combines the extraction step with an innovative synthesis of recycled Pt/C catalyst, leads to the manufacturing of an electrochemically active Pt/C catalyst with a high recovery efficiency of 96 %. Sensitivity analyses display that the recycling processes significantly relieve the environmental burdens associated with platinum mining and that their efficiencies directly relate to a decrease in environmental impacts
IMA11—interfacial fluid dynamics
No full textThis special issue presents recent advances on interfacial fluid dynamics, in link with the 11th conference of the International Marangoni Association organized in Bordeaux, France, on June 2023
Development of monoclonal antibodies in tablet form: A new approach for local delivery
No full textAmong the various pharmaceutical forms, tablets offer numerous advantages, like ease of administration, cost-effectiveness in production, and better stability of biomolecules. Beyond these benefits, the tablet form opens up possibilities for alternative routes for the local delivery of biopharmaceuticals such as oral or vaginal administration, thereby expanding the therapeutic applications of these biomolecules and overcoming the inconvenients associated with parenteral administration. However, to date there is limited information on the feasibility of developing biomolecules in the tablet form. In this study, we have evaluated the feasibility of developing monoclonal antibodies in the tablet form while preserving their biological properties. Different excipients and process parameters were studied to assess their impact on the antibody’s integrity during tableting. ELISA results show that applying compression pressure up to 100 MPa is not detrimental to the antibody’s binding properties when formulated from a lyophilized powder containing trehalose or sucrose as the major excipient. This observation was confirmed with SPR and ultracentrifugation experiments, which demonstrated that neither the binding affinity for both Fc and Fab antibody fragments nor its aggregation rate are affected by the tableting process. After compression, the tablets containing the antibodies have been shown to be stable for 6 months at room temperature
IMA11—interfacial fluid dynamics
Full text linkThis special issue presents recent advances on interfacial fluid dynamics, in link with the 11th conference of the International Marangoni Association organized in Bordeaux, France, on June 2023
Identification of the environmental hotspots of a recycling process - Case study of a Pt PEMFC catalyst closed-loop recycling system evaluated via life cycle assessment methodology
No full textProton-exchange membrane fuel cell (PEMFC) technology using green H2 as a fuel to produce decarbonized electricity is considered as a promising substitute for fossil fuels. However, its development is impeded by the use of critical raw materials, such as platinum which catalyzes the hydrogen oxidation and oxygen reduction reactions. In this paper, a novel closed-loop system for the re-manufacturing of platinum-based catalyst electrode from recycled material is developed. Three different recycling alternatives are compared using the life cycle assessment (LCA) methodology. The most promising one, which combines the extraction step with an innovative synthesis of recycled Pt/C catalyst, leads to the manufacturing of an electrochemically active Pt/C catalyst with a high recovery efficiency of 96 %. Sensitivity analyses display that the recycling processes significantly relieve the environmental burdens associated with platinum mining and that their efficiencies directly relate to a decrease in environmental impacts