Feed rate modeling in circular–circular interpolation discontinuity for high-speed milling

In this paper, a modeling approach is presented in order to evaluate feed rate during a circular interpolation in high-speed milling. The developed model depends on the type of discontinuity and the kinematic performance of the machine tool. To begin with, a feed rate modeling for circular interpolation with continuity in tangency is developed. After, the discontinuity in tangency between two circular interpolations is replaced by discontinuity in curvature by adding a fillet which is in relation to the functional tolerance ε imposed in the part design. An experimental study has been carried out to validate the models

Modélisation de la rugosité des surfaces fraisées

L’objectif de cette étude est de déterminer les paramètres de coupe permettant de réduire la rugosité des surfaces fraisées. Deux matériaux ont été étudiées : un acier au carbone et un acier inoxydable austéno-ferritique (duplex). L’outil utilisé est en carbure revêtu, de nuance M15. En fraisage en bout, un plan complet d’expériences constitué de 25 (52) essais (uniquement V et fz sont variables), a permis de déduire que le travail en avalant donne le meilleur état de surface. Les résultats des essais de ce plan complet ont été utilisés pour développer un modèle d’évolution de la rugosité en fonction de la vitesse de coupe et de l’avance par dent en utilisant le logiciel d’identification SiDoLo. En fraisage de face en avalant, un plan factoriel utilisant la table L25(53) a été utilisé pour déduire pour chacune des deux nuances, la combinaison de paramètres qui minimise la rugosité arithmétique moyenne Ra et la hauteur maximale de rugosité Rr Les résultats expérimentaux de ce plan factoriel ont permis de mettre en place des modèles empiriques pour exprimer la rugosité en fonction des paramètres de coupe. La comparaison des différentes méthodes a montré une bonne cohérence entre les différents résultats

Experimental characterization and numerical modeling of the three-dimensional anisotropic behavior of a thick sheet aluminum alloy AA2024-T351 using multi-scale approaches

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Finite element assessment of an affine self–consistent model for hexagonal polycrystals

International audienceThe present study aims at providing computations that can be used as reference solution to check mean-field nonlinear homogenization models for elastoviscoplastic constituents. These computations are based on finite element (FE) simulations of polycrystalline aggregates made of grains with hexagonal crystalline structure. A detailed statistical analysis has been performed for a specific grain located at the center of the aggregate by varying its neighboring grains. Comparisons are performed at the overall and local scales between simulations using the affine extension of the self-consistent scheme and the FE results for tensile and creep loading tests

Capabilities of the multi-mechanism model in the prediction of the cyclic behavior of various classes of metals

International audienceThe paper deals with an evaluation of the multi-mechanism (MM) approach capabilities in the prediction of the cyclic behavior of different classes of metallic materials. For this objective, the tests detailed in (Taleb, Int J Plast 43:1–19, 2013a) have been simulated here by the MM model. In these tests, six alloys were considered: two ferritic steels (35NCD16 and XC18), two austenitic stainless steels (304L and 316L), one “extruded” aluminum alloy (2017A) and one copper-zinc alloy (CuZn27). The specimens have been subjected to proportional and non-proportional stress as well as the combination of stress and strain control at room temperature. The identification of the material parameters has been carried out using exclusively strain controlled experiments under proportional and non-proportional loading paths performed in the present study for each material. The model may describe a large number of phenomena with twenty five parameters in total but, it appears that for a given material under the adopted conditions, the activation of all parameters may be not necessary. Our attention was focused mainly on the capabilities to predict correctly the cyclic accumulation of the inelastic strain including the shape of the hysteresis loops. The comparison between test responses and their predictions by the MM model are generally satisfactory with relatively small number of material parameters (between eight and thirteen according to the material). One can also highlight the capability of the MM model to describe a transient ratcheting without activation of the dynamic recovery term in the kinematic variables. Finally, the MM model deserves improvement for a better description of the cyclic behavior of anisotropic materials