Développement du procédé de micro-hydroformage de tubes

Le procéde d'hydroformage de tubes commence à être largement répandu dans l'industrie automobile pour la réalisation de pièces tubulaires complexes et mono-composant. Dans le cadre de cet article, on propose une miniaturisation de ce procédé à des structures de faibles dimensions (diamètres et épaisseurs respectivement inférieurs à 5mm et à 0,2mm). On présente iciun pilote expérimental instrumenté et les premiers tests effectués sur du gonflement libre en cavité ouverte sur des tubes de 4mm pour une épaisseur 0,1mm

A simplified analytical model for post-processing experimental results from tube bulging test: theory, experimentations, simulations

International audienceA complete analytical model combined with a very simple experimental procedure is proposed. It permits the post-processing of experimental measures to obtain the stress–strain curve for tubes very quickly and well adapted for industrial use. The quality of the results is proved by comparison with experimental measures and finite element results. Anisotropy in tube is revealed by plotting the (ρ,α) curve where ρ and α stand for strain and stress path respectively. Two quadratic criteria (Hill 1948 and Hill 1993) are studied and it is found that the Hill 1993 criterion seems the best to represent tube anisotropy for 316L stainless steel tube studied in the present paper

Prédiction de la zone de transformation de phase autour de la pointe de fissure d'un alliage à mémoire de forme au comportement dissymétrique en traction/compression

Une nouvelle zone de transformation de phase autour de la pointe de fissure est proposée pour des alliages à mémoire de forme. La présente analyse intègre la dissymétrie entre la traction et la compression dans le calcul de la surface critère. Les modes I, II, et III ont été calculés. Des essais de rupture en mode I ont été réalisés sur du Nickel-Titane avec une attention particulière portée à l?évolution du champ de température autour de la pointe de fissure

A new way to identify thin sheet behaviour : micro-in def

International audienceIncremental forming is a rapid prototyping process which uses a forming tool to form a sheet metal according to a predetermined trajectory. In this work, a micro incremental deformation test (Micro InDef test) derived from the principle of single point incremental sheet forming is developed and proposed. A complex mechanical loading is applied and has a strong potential for the identification of inelastic behavior using inverse method. In the first part, this work addresses the parameters identification and validation procedures of ductile damage behavior of ultra-thin sheet metal under very large strain during this instrumented Micro InDef test. An inverse finite element method based on the comparison between numerical and experimental axial forming forces of the micro incremental deformation test is employed to extract a coupled ductile damaged plastic model. In the second part, the objective is to prove the reliability of ductile damage parameters identification using forming force. The richness of data contained in forming force is quantified and compared to the one from tensile test. Firstly, the<br&gtverification of the estimated parameter’s reliability is done via a simple analysis based on the forming force sensitivity to material parameters and secondly by calculating elastoplastic and elastoplastic with ductile damage

Shape memory alloys cyclic behaviour : experimental study and modeling

10-11 ma

Analyse de la transformation de phase autour de la pointe de fissure d'un AMF

National audienc