A deterministic approach for shape and topology optimisation under material uncertainty in additive manufacturing

The present work aims at handling uncertain materials in shape and topology optimisation applied to additive manufacturing. More specifically, we minimise an objective function combining the mean values of standard cost functions and assume that the uncertainties are small and generated by two random variables. These two variables representing the amplitude of the Young's modulus correspond to the zone of porosity inclusion and surface roughness defects. A deterministic approach that relies on a secondorder Taylor expansion of the cost function has been proposed by Allaire & Dapogny [2]. The present work proposes a general framework to handle uncertainties of the Young's modulus in which its amplitude is divided into N zones and then applied onto two zones corresponding to the porosity inclusion and surface roughness defects. We demonstrate the effectiveness of the approach in the context of the level-set-based topology optimisation for the robust compliance minimisation of three-dimensional cantilever test cases

Mechanical Properties and Microstructural Characterization of Aged Nickel-based Alloy 625 Weld Metal

The aim of this work was to evaluate the different phases formed during solidification and after thermal aging of the as-welded 625 nickel-based alloy, as well as the influence of microstructural changes on the mechanical properties. The experiments addressed aging temperatures of 650 and 950 A degrees C for 10, 100, and 200 hours. The samples were analyzed by electron microscopy, microanalysis, and X-ray diffraction in order to identify the secondary phases. Mechanical tests such as hardness, microhardness, and Charpy-V impact test were performed. Nondestructive ultrasonic inspection was also conducted to correlate the acquired signals with mechanical and microstructural properties. The results show that the alloy under study experienced microstructural changes when aged at 650 A degrees C. The aging was responsible by the dissolution of the Laves phase formed during the solidification and the appearance of gamma aEuro(3) phase within interdendritic region and fine carbides along the solidification grain boundaries. However, when it was aged at 950 A degrees C, the Laves phase was continuously dissolved and the excess Nb caused the precipitation of the delta-phase (Ni3Nb), which was intensified at 10 hours of aging, with subsequent dissolution for longer periods such as 200 hours. Even when subjected to significant microstructural changes, the mechanical properties, especially toughness, were not sensitive to the dissolution and/or precipitation of the secondary phases

Remaillage conforme, capture exacte d’interface et contraintes géométriques pour l’optimisation topologique de structures mécaniques

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Soudage par Faisceau d’Electrons de l’Acier Inoxydable Austénitique stabilisé au niobium X6CrNiMoNb 17.12.2

DCNS a conduit une démarche complète de conception et de réalisation d’un équipement sous pression nucléaire en acier inoxydable austénitique stabilisé au niobium (Nb) en remplacement d’une technologie acier au carbone revêtu d’acier inoxydable. Ce changement de technologie a conduit en particulier à des travaux portant sur la qualification du soudage des soudures principales par faisceau d’électrons (FE) en forte épaisseur, et sur la contrôlabilité de ces soudures en fabrication et en service. La présentation développera la démarche de qualification du mode opératoire de soudage et présentera les résultats obtenus pour les soudures de production

Soudage par Faisceau d’Electrons de l’Acier Inoxydable Austenitique stabilise au niobium X6CrNiMoNb 17.12.2

DCNS a conduit une démarche complète de conception et de réalisation d’un équipement sous pression nucléaire en acier inoxydable austénitique stabilisé au niobium (Nb) en remplacement d’une technologie acier au carbone revêtu d’acier inoxydable. Ce changement de technologie a conduit en particulier à des travaux portant sur la qualification du soudage des soudures principales par faisceau d’électrons (FE) en forte épaisseur, et sur la contrôlabilité de ces soudures en fabrication et en service

A R&D software platform for shape and topology optimization using body-fitted meshes

International audienceTopology optimization is devoted to the optimal design of structures: It aims at finding the best material distribution inside a working domain while fulfilling mechanical, geometrical and manufacturing specifications. Conceptually different from parametric or size optimization, topology optimization relies on a freeform approach enabling to search for the optimal design in a larger space of configurations and promoting disruptive design. The need for lighter and efficient structural solutions has made topology optimization a vigorous research field in both academic and industrial structural engineering communities. This contribution presents a Research and Development software platform for shape and topology optimization where the computational process is carried out in a level set framework combined with a body-fitted approach

A R&D software platform for shape and topology optimization using body-fitted meshes

International audienceTopology optimization is devoted to the optimal design of structures: It aims at finding the best material distribution inside a working domain while fulfilling mechanical, geometrical and manufacturing specifications. Conceptually different from parametric or size optimization, topology optimization relies on a freeform approach enabling to search for the optimal design in a larger space of configurations and promoting disruptive design. The need for lighter and efficient structural solutions has made topology optimization a vigorous research field in both academic and industrial structural engineering communities. This contribution presents a Research and Development software platform for shape and topology optimization where the computational process is carried out in a level set framework combined with a body-fitted approach