Parameter file syntax change for strain weakening behavior

Hello all,

Those of you following the ASPECT github page have likely noticed that the development group is working on simplifying the material model structure by creating very specific rheology (and equation of state) “components”, which are then accesses by the material model.

One example of these components is “strain dependent” rheological behavior, which was implemented in the ViscoPlastic material model in order to simulate brittle or viscous strain-weakening behavior.

In moving the strain weakening portions of code to a new StrainDependent class (pull request #3219), we decided it was a reasonable time to remove backwards compatibility for an older syntax used to prescribe strain weakening.

If you are using the ASPECT master branch and have updated to include pull request (#3223, merged on September 23rd) the parameter syntax for strain weakening will no longer work.

Our normal procedure is to provide an update script that will automatically convert parameters to use the new syntax, but in this case it would have been overly complicated and we decided to use a forum announcement instead.

The old strain weakening syntax required specifying one or multiple parameters:
Use strain weakening
Use plastic strain weakening
Use viscous strain weakening
Use finite strain tensor

An earlier pull request changed this syntax to require only one input parameter (Strain weakening mechanism) to specify the type of strain weakening mechanism.

Examples of how to use the new syntax can be found in the following ASPECT tests:

If you have any questions about these changes or how to update your parameter file, please let us know!