Convergence analysis of Laplacian-based gradient elasticity in an isogeometric framework

A convergence study is presented for a form of gradient elasticity where the enrichment is through the Laplacian of the strain, so that a fourth-order partial differential equation results. Isogeometric finite element analysis is used to accommodate the higher continuity required by the inclusion of strain gradients. A convergence analysis is carried out for the original system of a fourth-order partial differential equation. Both global refinement, using NURBS, and local refinement, using T-splines, have been applied. Theoretical convergence rates are recovered, except for a polynomial order of two, when the convergence rate is suboptimal, a result which also has been found for the (fourth-order) Cahn-Hilliard equation. The convergence analyses have been repeated for the case that an operator split is applied so that a set of two (one-way) coupled partial differential equations results. Differences occur with the results obtained for the original fourth-order equation, which is caused by the boundary conditions, which is the first time this effect has been substantiated

Rôle prédictif des anomalies de la paroi artérielle carotido-fémorale sur la survenue d'une coronaropathie chez les sujets de moins de 45 ans

PARIS-BIUM (751062103) / SudocCentre Technique Livre Ens. Sup. (774682301) / SudocSudocFranceF

Chaleur spécifique a basse température de la famille Ni1-xCo xAl : observations en relation avec la structure de bandes de ces composés et la transformation martensitique de Ni1+yAl 1-y

Electronic specific heat and magnetic susceptibility measurements confirm the occurrence of a density-of-states peak between the Fermi levels of NiAl and CoAl (rigid band description). This peak would show, according to Connolly band calculations [3], a dominantly deg character. The NiAl Debye temperature is particularly low. This effect is probably connected with the proximity of a martensitic transformation which occurs for the Ni1+yAl1-y compounds when y > 0.2. Electron microscope observations on (Ni1-xCo x)1+yAl1-y alloys show that cobalt, when substituted to nickel, stabilizes the cubic phase, in agreement with the former statement.Des mesures de chaleur spécifique électronique et de susceptibilité magnétique confirment l'apparition d'un pic de densité d'états entre les niveaux de Fermi de NiAl et de CoAl (en bandes rigides). Ce pic, selon les calculs de Connolly [3], aurait un caractère dominant deg. La température de Debye pour NiAl est particulièrement basse. Cet effet est sans doute lié à la proximité d'une transformation martensitique qui apparaît pour les composés Ni 1+yAl1-y pour y > 0,2. Des observations en microscopie électronique sur des alliages (Ni1-xCox) 1 +yAl1-y montrent que la substitution de cobalt au nickel a bien pour effet de stabiliser la phase cubique

Le Contrat de Programme et de Recherche TiAl : un exemple de collaboration coordonnée entre recherche académique et Industrie

On présente dans cet article l'esprit qui gouverne la mise en place d'un CPR, la problématique industrielle des intermétalliques TiAl et une synthèse des résultats scientifiques marquants du CPR