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OSParticulas and NairnMPM are both MPM code engines. The difference is that OSParticulas is for new features in development, for proprietary or unpublished features, and for features not yet released to the open source version.


New OSParticulas Features

Some of the features in development and/or only available in OSParticulas. Some of these features are documented here (as listed as OSParticulas only), some are not yet documented, and others are just code improvements that don't need documentation. The unique features of OSParticulas include:

  • MPM modeling with large-deformation membranes in both 2D and 3D simulations.
  • A method to deform shapes when adding particles to the grid and to deform the particles in those shapes. One common use is to have rigid particles conform to a shape that is not aligned with grid axes such as a cutting tool with various cutting angles.
  • A new feature to allow materials to ignore cracks, which means the material can be "inside" the crack. Such materials interact with the fields above and below the crack by contact mechanics. The typical use is to wedge up a cracks or drive a nail or screw along crack plane.
  • A new feature to recognize presence of cracks and interfaces during heat conduction calculations.
  • Softening materials to implement anisotropic damage mechanics.
  • Phase transition materials to simulate transitions between two materials.
  • A Coulomb friction law with adhesion.
  • Tracking of particle spin, which can improve results in problems with rotation, especially for PIC (note: this feature is only enabled if OSParticulas is compiled with the ADD_PARTICLE_SPIN option defined in MPMPrefix.hpp).
  • Ability to set position-dependent initial velocities and spin momentum on particles.
  • Variable size elements (but still an orthogonal grid)
  • Exactly integrated finite-GIMP methods
  • A extended PIC methods known as XPIC

Some planned features being investigated are:

  • 3D Cracks
  • Extended PIC feature (XPIC)
  • Semi-implicit methods

Using OSParticulas

OSParticulas is available to members of the OSU MPM Consortium and selected collaborators with the research group of Prof. John A. Nairn at Oregonstate University. For details, you can contact us with an email. Once you are set up as a collaborator, you can check out OSParticulas using

svn checkout http://(server)/svn/OSParticulas/trunk mycheckout --username myusername

where (server) is the name for the computer currently storing the OSParticulas repository, mycheckout is any name you pick to be used for checked out folder, and myusername is your user name. After this command you enter your password and the files will be checked out. The server name, user name, and password will be provided when your account to check out OSParticulas is set up.

You can check out tagged or branched versions, a prior revision number, or the version on a specific date using the following checkout commands:

svn checkout http://(server)/svn/OSParticulas/tags/release-1.0 OSParticulas-1.0 --username myusername
svn checkout http://(server)/svn/OSParticulas/branches/MyBranch OSParticulas-MyBranch --username myusername
svn checkout --revision 185 http://(server)/svn/OSParticulas/trunk rev-185 --username myusername
svn checkout --revision {2014-07-04} http://(server)/svn/OSParticulas/trunk dated-2014-07-04 --username myusername

where you insert tag name, revision number or date as desired. The text before --username is the name of the folder when checkout on your computer and can be any text that helps you recognize the contents of the checkout.

OSParticulas Documentation

This wiki site documents both OSParticulas and NairnMPM; features that are only available in OSParticiulas will be noted. Those enabled to use OSParticulas can check the documentation notes in their download for any additional setup steps and for instructions on using any extra features available in OSParticulas that are not yet written up in these wiki pages.

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