Amélioration de la connaissance et de la prévision des distorsions d'aciers au traitement thermique

National audienceno abstrac

Three-dimensional numerical simulation of the nitriding process

This paper presents a three-dimensional numerical simulation of a nitriding process applied to an industrial component. The aim of the simulation is to predict the residual stresses and distortions due to volume changes induced by chromium nitride (CrN) and carbides (M$_23$C$_6$ et M$_4$C$_3$) formation. The simulation is performed in two steps. The diffusion of nitrogen and the precipitation of chrome nitride and carbides are first simulated. Then stresses and strains are calculated, assuming an elastic behaviour of the component, and using a volume expansion due to the precipitate concentration. The proposed approach is applied on a gear tooth. Small holes and details were neglected. For symmetry reasons, only half a tooth is taken into account. As the main phenomena take place through the first millimetre from the outer surface, a special attention was paid on meshing. The mesh used for the diffusion and precipitation analysis is composed of 1 130 000 nodes and 1 110 000 elements. For the mechanical analysis, a coarser mesh including only 165 000 nodes and 290 000 elements was used

Overview of the In-Space Propulsion (ISP-1) project

The intent of this publication is to provide an overview of the progress of the ISP1 project over the 2011-2012 period. In the frame of the European FP7 Collaborative Project, Focused Research Project Theme 7, the In- Space Propulsion (ISP-1) project GA# 218849 was initiated in 2009 with the objective of improving the knowledge and the techniques which are necessary for future space missions relying on cryogenic propulsion. The ISP-1 program is structured into five main work packages which deal with various technological issues associated to the development of a Low Thrust Cryogenic Propulsion system. It concentrates on liquid oxygen, liquid hydrogen, and liquid methane propellants. The subject addressed by the work packages are the LOX-methane combustion, the hydrogen embrittlement, the material compatibility and tribology in liquid oxygen, the energy management of low thrust propulsion system, and the development of electrically driven cryogenic turbopumps

Structural and thermal investigation for FBAR reliability in wireless applications

International audienc

Quantitative analysis of heat affected zone due to ultra-short laser pulses using transmission electron microscopy.

International audienc

Heat affected zone in micro-drilling of metals by femtosecond laser pulses.

International audienc

Building blocks for a Ka band switch matrix using MEMS and printed circuit board technology

International audienceThe key objectives of the SMARTIS (SMART thin film on alumina Substrate) project are presented in this paper. A focus is made on the design of the DPDT switches and on the optimization of the elementary building blocks necessary for the development of a Ka band switch matrix on Printed Circuit Board