Chatter milling modeling of active magnetic bearing spindle in high-speed domain

A new dynamical modeling of Active Magnetic Bearing Spindle (AMBS) to identify machining stability of High Speed Milling (HSM) is presented. This original modeling includes all the minimum required parameters for stability analysis of AMBS machining. The stability diagram generated with this new model is compared to classical stability lobes theory. Thus, behavior’s specificities are highlighted, especially the major importance of forced vibrations for AMBS. Then a sensitivity study shows impacts of several parameters of the controller. For example, gain adjustment shows improvements on stability. Side milling ramp test is used to quickly evaluate the stability. Finally, the simulation results are then validated by HSM cutting tests on a 5 axis machining center with AMBS

Tuning of a Nonlinear Energy Sink using multi-stability

International audienceThis work addresses the development of a nonlinear absorber based on the concept of a Nonlinear Energy Sink(NES) under different multi-stable configurations. The potential energy of the system can be written under a potential thatpossesses two or more stable equilibrium positions separated by saddle points. The study of the dynamics at different timescales leads to the computation of the Slow Invariant Manifold (SIM) where singular points indicate the possible occurrenceof Strongly Modulated Responses (SMR). It is shown that, compared to a bi-stable NES, the threshold activation of amultistable NES can be significantly lowered with same dissipation ability

Large Retaining Structures Reinforced by Geosynthetics: French Case Histories

French experience in earth embankments reinforced by geosynthetics dates back more than 25 years. This technique was developed on the basis of reference structures fitted with instruments to monitor their behaviour. Three of the largest structures built have been chosen in this paper as they are typical of the different construction technologies used in France

Dynamical modeling of spindle with active magnetic bearing for milling process

A dynamical modeling of spindle with Active Magnetic Bearing (AMB) is presented. All the required parameters are included in the model for stability analysis. The original map of stability is generated by Time Domain Simulation. The major importance of forced vibrations is highlighted for a spindle with AMB. Milling test are used to quickly evaluate the stability. Finally, the simulation results are then validated by cutting tests on a 5 axis machining center with AMB

Vendor Managed inventory, from concept to processes, for an unified view

International audienceIn a supplier-customer relationship, Vendor Managed Inventory (VMI) is currently used to monitor the customer's inventory replenishment. However the integration of VMI implies consequences on the collaboration process that links the different planning processes of each partner. This paper proposes a unified view of the VMI: beyond the short term pull system inventory replenishment, partners have to share their vision of the demand, their requirements and their constraints to fix middle/long term common objectives for each article concerned by VMI. There are many ways to specify these links between VMI and partner's planning processes

Connaissance de la biodiversité Elaboration du document d'objectifs du site Natura 2000 du Mont Ventoux

Dans le cadre de la mise en uvre de la directive européenne « habitats » en région Provence-Alpes-Côte d'Azur, l'Office national des forêts s'est vu confier l'élaboration du document d'objectifs du site Natura 2000 Mont Ventoux (Vaucluse). C'est ainsi que, sur cette véritable île biogéographique montagnarde en zone méditerranéenne, ont été menés à bien inventaires et cartographies des habitats ainsi que de quelques éléments de la faune et de la flore. Une attention particulière a été portée sur l'analyse des dynamiques évolutives. Cette approche a été croisée avec une analyse des activités humaines pour déboucher sur une définition concertée des enjeux en matière de « patrimoine biologique » et des objectifs et plan d'actions pour y répondre. L'intérêt et les limites de cette approche de la biodiversité et ses conséquences sur la gestion sont ici évoquées. Ces considérations valent pour nombre d'autres sites Natura 2000 de la région

PRELIMINARY DISCRETE MODELLING OF LANDFILLS CLAY BARRIER

International audienceSUMMARY: The Discrete Element Method is used to investigate the tensile behaviour and cracks mechanisms of a clay material submitted to bending loading. It is the case of compacted clay liners in landfill cap cover application. Such as the soil tested in this study is plastic clay, the distinct elements model was calibrated with previous data results by taking into account cohesive properties. Various contact and cohesion laws are tested to show that the numerical model is able to reproduce the failure mechanism. Numerical results are extending to simulate a landfill cap cover

Innovative process engineering: a generic model of the innovation process

International audienceInnovation can be represented as a knowledge transformation process perceived with different levels of granularity. The milestones of this process allow assessment for its each step and set up feedback loops that will be highlighted. This innovation process is a good starting point to understand innovation and then to manage it. Best practices being patterns of processes, we describe innovation best practices as compulsory steps in our innovation process. To put into practice, the management of innovation in a concrete organisation, an alignment (in our case a mapping) between a repository of business processes and our typical innovation process, helps to describe which best practice applies to which business process

La démarche Natura 2000 sur le mont Ventoux.

La démarche Natura 2000 est révélatrice des enjeux actuels, où la société, désormais urbaine, porte un nouveau regard sur ses espaces naturels. De nouvelles attentes quant aux forêts et espaces naturels se sont révélées et l'évolution des politiques de protection de la nature ont permis de s'y adapter : on protège les milieux et les espèces à travers leurs habitats, sans oublierd'y associer les composantes socio-économiques. Ainsi, la directive Habitat doit aboutir à des protections, mais surtout à une démarche contractuelle