Today, optical full-field techniques to measure kinematics data, like digital image
correlation, mark tracking technique or grid method, are usually employed to
study the mechanical behavior of materials and structures in the zone of interest
with a size from some millimetres to one meter. Their success is linked to an
easy implementation by using an adaptable camera/lens setup and the possibility
to realize a pattern as a grid of dots and lines or a speckle. When we want to
lead studies for microscopic or sub-microscopic scales, difficulties appear: it
is also necessary to use another more complex observation system, often a
scanning electronic microscope (SEM), and it is more difficult to make a
pattern at these scales.
In the framework of LABEX INTERACTIFS and FEDER 2014-2020 program, the institute P’ of
Poitiers has bought a SEM with two beams (Field emission gun (FEG) / focalised
ion beam (FIB)), which is an original setup in France. It allows to observe
micro samples (some microns even less) and to build them by machining thanks to
FIB. It will also possible to study different mechanical phenomena at very
small scale as elementary strain mechanisms during elasto-plastic transition.
The goal of
this thesis is to couple full-field techniques and FIB-SEM in order to build a
suitable metrological protocol to quantify displacements and strains at these
scales. A part of the work will to assess metrological performances of the new
FIB-SEM in terms of image quality and to research adapted patterns which could
be made by FIB (machining or deposit). Another part will to adapt measurement
techniques to particular strain mechanisms at these scales as the strain
localisation by shear bands. The developed protocol will be used in particular
to study plasticity of micro pillars under compression and the influence of
micro defaults on the appearance of damage and cracks.
The candidate should have knowledge of solid mechanics or material physics. A practice
of optical methods and electronic microscopy will be considered as an advantage.
Valery Valle ; Professor
Pascal Doumalin ; Assistant-Professor
Mechanics Speciality
Contact details
Valery Valle ou Pascal Doumalin
Institut P’ Equipe PEM
Tel : 05 49 49 65 45 ou 40
valery.valle@univ-poitiers.fr,
pascal.doumalin@univ-poitiers.fr
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