Comportement des monocristaux en AMF. Application au comportement des polycristaux :

Not availableLes résultats obtenus lors de la simulation d'un fluage anisotherme soumis à de faibles containtes ne sont pas satisfaisants. Le nombre de variantes activées au cours de tels essais est d'autant plus important que la contrainte appliquée est faible (Apparition de groupes auto-accomodants formés de quatre variantes). C'est pourquoi, nous proposons une nouvelle formulation qui prend en compte ce nombre grandissant de variantes activées. Cette approche donne naissance à une nouvelle matrice d'interaction qui renseigne sur la compatibilité ou l'incompatibilité pour des regroupements de quatre variantes au lieu de deux avec la matrice d'interaction classique. Cette matrice, associée à un nouveau critère de sélection des variantes, améliore considérablement les résultats obtenus lors de la simulation d'un essai de fluage anisotherme pour un AMF monocristallin à base cuivre. Cette démarche a été employée pour modéliser les polycristaux, mais les résultats sont moins probants et restent à améliorer

Comportement des monocristaux en AMF. Application au comportement des polycristaux

METZ-SCD (574632105) / SudocCACHAN-IUT (940162201) / SudocSudocFranceF

Influence of the microstructure on the SMA behavior

10th International Conference on Martensitic Transformations, ESPOO, FINLAND, JUN 10-14, 2002International audienc

New anisothermal creep modelling for Cu-based shape memory alloys

Autumn meeting of the French-Metallurgy-and-Materials-Society (SF2M), PARIS, FRANCE, OCT 29-31, 2001International audienc

Finite element simulation of a multicrystal in shape memory alloy

7th European Mechanics of Materials Conference, Frejus, FRANCE, MAY 18-23, 2003International audienc

Influence of microstructural parameters on shape memory alloys behavior

IUTAM Symposium on Mechanics of Martensitic Phase Transformation in Solids, HONG KONG UNIV, SCI & TECHNOL, HONG KONG, PEOPLES R CHINA, JUN 11-15, 2001International audienc

Non fracture prediction of a C–Mn weld joint in brittle to ductile fracture transition temperature range. Part II: Determination of the stress-based criterion parameters and evaluation of its transferability

International audienceThis paper evaluates the brittle fracture risk for a C–Mn weld in the brittle-to-ductile transition: the criterion considered is based on a critical stress σth, with the failure probability related to the volume around the crack where the maximum principal stress exceeds σth. In Part II, the criterion is calibrated using more fracture tests at lower temperature. The capacity of the criterion to predict the probabilities of failure is validated. Finally, its transferability to another geometry is evaluated and appears to be possible

Determination of the interaction energy in the martensitic state

8th International Symposium on Plasticity, WHISTLER, CANADA, JUL 17-21, 2000International audienc

Brittle fracture analysis of Dissimilar Metal Welds

International audienceThis paper deals with a fracture mechanics analysis of a narrow-gap Dissimilar Metal Weld (DMW) in the brittle fracture domain. The considered case is a Ni base alloy weld joint between a ferritic component and an austenitic pipe and the aim of the present study is to show that in the same loading conditions, the weld joint is less sensitive to the brittle fracture than the nearby ferritic part of the component.The bases of the proposed qualitative study rely on a stress-based criterion model, using a threshold stress (σth) below which the cleavage cannot occur. From that criterion, brittle fracture risk is evaluated, then compared between two positions of a postulated crack: one in the Heat Affected Zone (HAZ) of the ferritic material, the other in Base Metal (BM) far from the weld joint.For the experimental part of this comparison, one mock-up containing a DMW is used. From this mock-up, a large number of specimens of various types and with various crack locations was tested at low temperature. In parallel to that extensive experimental program, Finite Element Analysis has been done. The main result of that F.E.A. is that, due to the mismatch between the different materials, the brittle fracture risk is lower in the HAZ because of the stress relaxation with plasticity in the weld material and loss of constraint in the cracked section.This paper presents firstly a survey of DMW integrity evaluation, then the criterion used for the comparison, the experimental work and the F.E.A. made to show qualitatively the highest risk of brittle fracture of the homogeneous ferritic material compared to the DMW one