Assessment of the in-plane biomechanical properties of human skin using a finite element model updating approach combined with an optical full-field measurement on a new tensile device

International audienceHuman skin is one of the most important organ of the body. The assessment and knowledge of its properties are very useful for clinical or cosmetic research. Many techniques are used to measure the mechanical properties of this organ, like suction, indentation, torsion or tension tests. The aim of this paper is to present a new device based on tension technique and combining mechanical and optical measurements. The whole procedure used to assess the displacement field as described, and first results of tests performed in vivo are shown

Effect of tool profile and fatigue loading on the local hardness around scratches in clad and unclad aluminium alloy 2024

Nanoindentation has been used to study the hardness changes produced by scratching of aluminium alloy AA2024, with and without a clad layer of pure aluminium. The hardness was mapped around scratches made with diamond tools of different profiles. One tool produced significant plastic damage with associated hardening at the scratch root, whilst the other produced a 'cleaner' cut with no hardening. The different behaviours and are attributed to whether the tool makes the scratch by a 'cutting' or a 'ploughing' mechanism. The degree of plastic damage around the scratches has been correlated with peak broadening data obtained using synchrotron X-ray diffraction. There was no change observed in the local hardness around the scratch with fatigue loading

Modélisation numérique du comportement à l'usure de la fonte à graphite sphéroïdal

International audienceSince 1948, the date of its invention, nodular cast iron becomes more and more used. This, thanks to the mechanical and tribological performances which the cast iron can offer, compared to the other types of steel. Ductile iron is used for several structural applications particularly in that which require rigidity combined with good usinability. The second largest area of application of ductile iron is the automobile industry thanks to its lower density (10% less to steel), good wear resistance and its low coefficient of friction. In this work an experimental wear test allow to emphasize the role of graphite in the reduction in apparent friction coefficient during wear. Numerical simulations of sphere in plan friction test, with finite element code ABAQUS, make it possible to study the wear of nodular cast iron. The numerical simulation makes it possible to highlight the concentration of the perlitic stress caused by the presence of graphite.A partir de 1948, la date de son invention, la fonte à graphite sphéroïdal devient de plus en plus utilisée. Ceci grâce aux performances mécaniques et tribologiques que peut offrir la fonte par rapport aux autres types d'acier. La fonte ductile est utilisée pour plusieurs applications structurelles particulièrement dans celles qui nécessitent une rigidité combinée avec une bonne usinabilité. Le second large domaine d'utilisation de la fonte ductile est l'industrie automobile grâce à la faible densité par rapport à l'acier 10%, sa bonne résistance à l'usure et son faible coefficient de frottement. Dans ce travail des essais d'usure expérimentaux permettent de mettre en valeur le rôle du graphite dans la diminution de coefficient de frottement apparent au cours de l'usure. Des simulations numériques par le code d'élément finis ABAQUS de l'essai de frottement sphère plan permettent d'étudier l'usure de la fonte à graphite sphéroïdal. La simulation numérique permet de mettre en évidence la concentration des contraintes perlitiques à cause de la présence du graphite

Multi-scale tribological analysis of the technique of manufacture of an obsidian bracelet from Aşıklı Höyük (Aceramic Neolithic, Central Anatolia)

International audienceTribological analysis is employed in a pilot study of the technological steps involved in the manufacture of a polished obsidian bracelet from Aşıklı Höyük, an Aceramic Neolithic site in Central Anatolia (8,300-7,500 cal. B.C.). The study includes morphological analysis of the bracelet, based on profile measurements, and identifications of wear variations indicated by surface topographic features and parameters. The manufacturing skill that is revealed suggests early appearance of a regional tradition of obsidian working, which reached its full development in the 6th millennium cal. B.C. with the production of various ornamental objects, including mirrors and vessels. The cultural record and location of Aşıklı Höyük make the site important for our understanding of the technological developments during the early Neolithic in Anatolia