Aurélien Maurel-Pantel

3D FEM simulations of shoulder milling operations on a 304L stainless steel

Abstract This paper describes investigations realised to perform simulations of shoulder milling operations on AISI 304L stainless steel using the commercial software LS-Dyna©. A Lagrangian formulation with an explicit solution scheme and a penalty contact algorithm has been used. Many experiments were performed in shoulder milling configurations in order to study the machinability of this material and also to validate the results obtained from the developed 3D finite element model. In the simulations, the material behaviour is modelled with a classical Johnson–Cook law. Some enhancements and simplifications had to be made in geometry, meshing, friction and temperature considerations for limiting the calculation time. The final aim consists to obtain realistic numerical cutting forces for shoulder milling operations.

Process parameters influence on mechanical strength of direct bonded surfaces for both materials: Silica and Zerodur glasses

Direct bonding is of particular interest for optical system manufacturing for spatial application. This technology is already used in terrestrial optical system manufacturing because of the very high precision of the process and complex geometries are able to bond. However, even if a first prototype already passed with success space environment test, quantification and improvement of the mechanical strength of assemblies are essential to validate the assembly’s life expectancy and to validate the European Space Agency standards. So, this work proposes to study the influence of process parameters, such as roughness, relative air humidity during room temperature bonding, annealing time and temperature, on mechanical strength of an elementary mechanical structure using a double shear test procedure and cleavage tests. At the same time, the performances of fused silica and Zerodur® glasses are compared. For the process considered in this study, a parallel is made between chemical phenomena, surface roughness and mechanical strength. In the end, cleavage tests confirm the choice of the optimal process parameters and highlight a damaging phenomenon of bonded interfaces with successive re-adhesion.