Advances in martensitic transformations in Cu-based shape memory alloys achieved by in situ neutron and synchrotron X-ray diffraction methods

This article deals with the application of several X-ray and neutron diffraction methods to investigate the mechanics of a stress induced martensitic transformation in Cu-based shape memory alloy polycrystals. It puts experimental results obtained by two different research groups on different length scales into context with the mechanics of stress induced martensitic transformation in polycrystalline environment

On the difficulty of finding spines

We prove that the set of symplectic lattices in the Siegel space $\mathfrak{h}_g$ whose systoles generate a subspace of dimension at least 3 in $\mathbb{R}^{2g}$ does not contain any $\mathrm{Sp}(2g,\mathbb{Z})$-equivariant deformation retract of $\mathfrak{h}_g$

Simulation de la diffraction cohérente d'un film polycristallin

http://hdl.handle.net/2042/38756International audienceLa diffraction cohérente permet de caractériser les hétérogénéités de déformation dans un polycristal. La figure de diffraction dans l'espace réciproque dépend de la forme du grain illuminé et de son champ de déformation. Dans ce travail, La déformation d'un film mince polycristallin est calculée par élément finis et les figures de diffraction de certains grains en sont déduites en fonction de la déformation imposée. L'influence de la densité de maillage, de la taille et de la forme du grain illuminé est étudiée

Advances in friction stir welding of steel : Project HILDA

A microstructure and property evaluation of friction stir welded DH36 6mm plate has been undertaken. The study examined a wide range of process parameters and, from this, a process parameter envelope has been developed and an initial process parameter set established that gives good welding properties. Thermo-mechanical deformation studies were developed to generate flow stress regimes over a range of stain rates and temperatures and these data will support the on-going local numerical modelling development. A preliminary thermo-fluid model has been developed to predict temperature and material flow during the FSW of steel grade DH36. In this model, materials are considered as highly viscous incompressible fluid. The welded material is flowing around the rotating tool thanks to the modelling of the friction at tool/workpiece interface. In parallel, a global numerical model is being developed to predict the inherent residual stresses and distortion of FSW butt welded assemblies often in excess of 6m long plate