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3-year PhD position at University Paris-Est on multiscale cracking modeling in 3D printed glass-polymer composites

Submitted by Julien Yvonnet on
job

 

We are looking for highly motivated PhD candidates to study the multiscale cracking in 3D printed glass-polymer composites. The main objectives of the project are to develop a multiscale numerical modeling framework for cracking in PA12/glass beads samples obtained by additive manufacturing (Selective Laser Sintering, SLS) and to combine these numerical tools with experimental 3D imaging and in-situ mechanical testing techniques to identify the models. The PhD is part of a funded national research project involving several academic institutions and an industrial partner.

The normal-auxeticity mechanical phase transition in graphene

Submitted by qing.peng on
research
graphene
auxitetic
Negative Poisson's ratio
normal-auxeticity mechanical phase transition

When a solid object is stretched, in general, it shrinks transversely. However, the abnormal ones are auxetic, which exhibit lateral expansion, or negative Poisson ratio. While graphene is a paradigm 2D material, surprisingly, graphene converts from normal to auxetic at certain strains. Here, we show via molecular dynamics simulations that the normal-auxeticity mechanical phase transition only occurs in uniaxial tension along the armchair direction or the nearest neighbor direction. Such a characteristic persists at temperatures up to 2400 K.

Toward realization of computational homogenization in practice

Submitted by Ken Lippmann on

Dear all,

I have read the article of Yuan and Jacob Fish entitled "Toward realization of computational homogenization in practice" and realize that they have published the source code they used in their paper. Unfortunately, I cannot download the code from the link that the authors provided. I wonder if any of you have downloaded the code before. If so, please kindly share the code to me.

Thanks in advance.

Ken

Localization and instability in sheared granular materials: Role of friction and vibration

Submitted by Ahmed Elbanna on
research
granular material
shear bands
friction
vibration
stick-slip

Shear banding and stick-slip instabilities have been long observed in sheared granular materials. Yet, their microscopic underpinnings, interdependencies and variability under different loading conditions have not been fully explored. Here, we use a non-equilibrium thermodynamics model, the Shear Transformation Zone theory, to investigate the dynamics of strain localization and its connection to stability of sliding in sheared, dry, granular materials. We consider frictional and frictionless grains as well as presence and absence of acoustic vibrations.

Objective Fracture Parameters and a Paradox for Interface Cracks

Submitted by Bin Liu on
research
fracture mechanics

Due to the oscillatory singular stress field around a crack tip, interface fracture has some peculiar features. This paper is focused on two of them. One can be reflected by a proposed paradox that geometrically similar structures with interface cracks under similar loadings may have different failure behaviors. The other one is that the existing fracture parameters of the oscillatory singular stress field, such as a complex stress intensity factor, exhibit some nonobjectivity because their phase angle depends on an arbitrarily chosen length.

PhD scholarship in Ecole Polytechnique, Paris, France

Submitted by Kostas Danas on
job
instabilities
Magnetorheological elastomers
experiments
finite elements

One Ph.D. position is now available starting October 2017 on harnessing instabilities in magnetorheological elastomers. The PhD will be pursued in the Solid Mechanics Laboratory of Ecole Polytechnique, Paris, France. The potential student will work on the development of new experimental procedures and numerical models for the fabrication and testing of new magnetorheological elastomeric devices that operate in the postbifurcation regime by proper combination of mechanical and magnetic loadings.

Masonry modeling in Abaqus

Submitted by eng.femiran on

here we are to tell you how we can model masonry in abaqus cae.
there are 3 ways:
1-micro modeling
2- macro modeling
3- micro-macro modeling(HOMOGENIZATION)
micro modeling; 
in this method all parts should be modeled in abaqus separately.
but notice that don't use shell to modeling grout because of 3d properties of grout and cohesive characteristics.
this method is suitable for small masonry panels with 2-3 layers of brick.

A simple finding on variable amplitude (Gassner) fatigue SN curves obtained using Miner’s rule for unnotched or notched specimen

Submitted by Mike Ciavarella on
research
Fatigue
variable amplitude
notches
critical distance method

We provide a very simple result for a problem which has been often neglected (variable amplitude loading) in academia, but which is of paramount importance in real engineering situations, where fatigue is almost never "constant amplitude".

We found few cases where we could check this extremely simple result, but it worked very well.  We would welcome further verifications.

The paper is in press here.

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