--> The recommended release of microMegas for most users is mM 4.3
In case you wants to publish work including mM simulation results, please be so kind as to mention "microMegas" in the Acknowledgement Section.
Download the last release of mM ==> mM.tar.gz
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mM version 4.3 is the last recommended release of the DD simulation code microMegas for most users.
This release of mM is known to be very stable and to allows large scale parallel simulations.
mM version 4.2 is the recommended release of the DD simulation code microMegas for most users. It contains a bunch of bug fixes and new features:
- The parallel computation algorithms were improved for simulations with large number of segments
- Free surfaces problems (with complex shapes) are fixed
- Simulation can be restarted with increasing values of NSEGMAX (the dimension of many fixed tabs)
- The non-singular dislocation field formula proposed by "Wei Cai and al." can be used. The default core spreading radius is set to 0.5b
- The simulation memory usage is reduced
- ...
mM version 4.1 is a more stable and improved version of mM 4.0. In what follows, major additions and modifications are listed:
- Simulations in structures with convex and concave free surfaces are now taken into account.
- A local rule for dislocation loop nucleation is now included
- Heterogenous loading using FE calculation results is possible
- Visualization of the mM film with the Paraview code is now included
- ...
mM version 4.0 contains many new features. In what follows, major additions and modifications are listed:
- Simulations with free surfaces are now taken into account.
- The possibility to run two mM simulations in parallel to simulate the plasticity of two connected plastic phases is OK
- All the coding needed to run DCM (Discrete-Continuous Model) simulations is now included in mM
- and many other things ...
mM version 3.4.1 is a bug fix release of mM 3.4
A bug, introduced in mM 3.4, on the mobility of dislocation segments is corrected
A new strain rate control algorithm is defined to improve the simulation accuracy
mM version 3.4 is a transitory release. This version is more stable than mM 3.3 and for this reason larger time steps can be used. In what follows, major additions and modifications are listed:
A small application named 'film2para' is now part of the project. This application allows showing dislocation microstructure made with mM with the help of the 'paraview' visualization code.
A small bug in the 'multipole' algorithm is corrected.
A new local line tension solution was coded. This solution is dedicated to comparison between mM and atomic simulations.
A new rule of line discretization is proposed for the segments close to pinning points.
A new optimization of the procedure of obstacles search is made.
Particules shearing as a function of a critical stress or an activation volume can be simulated.
Problems in the simulation 'carto' mode and 'biphase' mode was corrected
mM version 3.3 contains several new features, is faster and more robust than previous releases. In what follows, major additions and modifications are listed:
New crystal symmetries are included, specifically simple cubic and MgO.
The computation of the distortion field is now included. This quantity is helpful to monitor rigid body rotations during a tensile test.
The topological part of mM dedicated to contact reactions is reformulated to be more general.
The interaction between dislocations and small incoherent (shearable or non-shearable) particles is effective in mM and operational. A random microstructure of particles can be defined with the help of a new input file named "biphase". Alternatively, a given microstructure of particles can be defined in file named "part".
The usable loading conditions are extended to include any type of homogeneous applied stress tensor. This modification required the calculation of generalized Schmid factors.
Problems with line tension stability were reported to arise upon working at very small scales (simulation cell in the nanometer range). To solve this: - a cut-off is introduced in the logarithmic term of the line tension. – A regularization of the local curvature is implemented. For the local curvature calculation, we now consider a constant section of dislocation line proportional to the discretization length.
Several modifications were brought to the simulation output files. Output text files now have the extension ".txt". Important data are collected in two files: -
"graph.txt" for the main quantities,)including stress, strain, strain-rate, etc. - "stat.txt" : for some statistical quantities of interest like mean junction length, mean effective stress , number of segments connecting cross-slipped dislocations, etc. A header is systematically added to all output files to fix column definition.
Several modifications have also been made to the input files. One can now run a simulation with an initial dislocation microstructure that is the superposition of two microstructures previously obtained in two different runs (seg_save file). Alternatively, the simulation can be restarted with configurations where some dislocation loops were removed by hand.
Released by B. Devincre (mM 3.3) 05-2008
Parallel computing with MPI library is working well in all simulation conditions (with active cross-slip, with active "multipole" and/or "wait" algorithm).
Cross-slip is generalized to crystal lattices with more than two slip systems sharing the same Burgers vector (e.g. BCCs).
The implementation of interfaces is improved. Three different solutions are proposed: (see variable "GB" in the input control file).
The algorithm identifying contact reactions between segments (e.g. to form junction) is reformulated and optimized.
Initial and restart file format are now identical. The connection between segments in the input segment list can be forced when using negative values for the neighbor indexation.
Four different solutions for the local line tension approximation are available.
New features are implemented in the graphical interface. It is possible to visualize the extended periodic glide planes of the dislocations or large volume elements including replicas of the simulated reference volume.
More and more parts of the simulation are commented using a blend of French, US- and UK-English ;)
Released by B. Devincre (mM 3.2) 06-2006
Many small bugs have been fixed. Especially, the problem of simulation crash associated with the accumulation of dislocation debris formed during cross-slip is seemingly solved (don't forget reducing your time step when cross-slip is activated). The rigid body rotation of the simulation reference box induced by plastic shear is now taken into account in uniaxial loading conditions ...
Released by B. Devincre (mM 3.1) 04-2005
mM is an efficient Dislocation Dynamics program intended for the modeling and visualization of dislocation-based plastic deformation in crystals. The program is aimed at scientific research, but can be used for teaching purposes. mM runs on a wide range of architectures based on UNIX systems. It is based on FORTRAN 95 for the calculation part and C + X11 libs for the visualization interface. mM computing can be executed on clusters of workstations with the help of MPI library. More information in the mM manual ...
Released by B. Devincre (mM 3.0) 11-2004
Last update: 19/06/17