Tools for Modifying the Model

A number of Python scripts and Abaqus/CAE plug-ins are packaged with the Heart Model. After you have made changes to the Heart Model, you should regenerate a complete simulation model that is ready to be analyzed by Abaqus by running the appropriate scripts and plug-ins described below. A readme.txt file is provided with each script or plug-in that provides details on usage and limitations. In some cases, you will need to edit the source code for the Python plug-ins described below. You should contact the Virtual Human Modeling group at SIMULIA for assistance in modifying the plug-ins.

This page discusses:

Fix Keyword Conflicts

The Heart Model includes Abaqus/CAE plug-ins for the electrical and mechanical models that fix the conflicts related to user additions and modifications to the model that are reported by Abaqus/CAE when you submit a simulation job for analysis. You should execute the plug-ins if the analysis fails due to the presence of the *CONFLICTS keyword. The plug-in should be executed as the very last step in modifying the model in Abaqus/CAE before submitting an analysis job.

If you remove a meshed part from the Heart Model, you must remove the corresponding part name from the plug-in. Similarly, if you add a meshed part to the model that utilizes any of the heart model constitutive laws, you must add the part name to the plug-in.

Remap the Initial Fiber Orientations

If you make any modifications to the geometry of the atria, ventricles, proximal vasculature, or any portion thereof that necessitate remeshing, you must use the oriMap plug-in to remap the initial fiber orientations.

Regenerate Element Sets

If you remesh any portion of the Heart Model, you may lose some of the predefined element sets that are required by the analysis. You should check if any element sets exist for a region you have remeshed and, if required, run the regenElsets.pyc Abaqus/CAE script to reassign the elements in the predefined sets.

Scale Material Properties

The material property parameter values (for the passive, active, and electrical constitutive laws) of the Heart Model are encrypted. You can modify the default values using two Abaqus/CAE plug-ins—Adjust Electrical Material Properties and Adjust Mechanical Material Properties. You can either selectively scale any of the existing values or supply the absolute value of each and every parameter.

Determine the Zero-Stress State

The CAD geometry used to create the finite element mesh corresponds to the heart at 70% diastole-a pressurized/loaded state. However, when the geometry is meshed, the resulting elements are stress and strain free. Therefore, an inverse problem must be solved to calculate an initial stress state corresponding to 70% diastole. SIMULIA has solved this problem and determined an initial set of nodal locations that correspond to what would be a zero-stress state (a "deflated mesh") for the baseline model. When this mesh is pre-loaded during the simulation, it brings it back to very closely matching the original CAD geometry.

You must repeat this inverse procedure if you do any of the following.

  • Create new elements. For example, when you remesh any part of the heart.
  • Change any loads or boundary conditions during the PRE-LOAD step.
  • Change any material parameters.

You may need to repeat the inverse procedure when you add a medical device to the Heart Model (see Adding Medical Devices to the Heart Model for more information).