Predefined Fields for Sequential Coupling

Nodal temperatures, normalized concentrations, and electrical potentials can be stored as functions of time for use in subsequent analyses. Temperatures can be stored in either the results (.fil) file or the output database (.odb) file, but normalized concentrations and electrical potentials can be used only if they are stored in the output database file. Saved values must be read into the new analyses as predefined fields. See Node Output and Writing Nodal Output to the Output Database.

To define the temperature field at different times in the current analysis, you read the nodal temperatures stored as a function of time in the heat transfer results or output database file. Nodes can be removed for the current problem; for example, in a sequential thermal-stress analysis elements that represent nonstructural parts of the heat transfer mesh (such as insulation or cooling fluid) can be omitted in the stress analysis. When the heat transfer results file or output database file is read, temperatures at nodes that are not present in the mesh for the current analysis are ignored.

You must specify the name of the thermal analysis results file or output database file that contains the required nodal temperatures. The file extension is optional. If the heat transfer model and the current analysis model share the same mesh, the default is the results file. If the heat transfer model and the current analysis model have dissimilar meshes, the output database file must be used. See Reading the Values of a Field from a User-Specified File for more information.

If both models contain part and assembly definitions, the part (.prt) files from both analyses are required to transfer temperatures from the thermal analysis to the current analysis. If the thermal model is defined in terms of an assembly of part instances, the current analysis must be as well. The part instance names and local node numbers must be the same in both analyses for the nodes at which temperatures are transferred.

To define predefined fields at different times in the current analysis, you can read nodal temperatures, normalized concentrations, or electric potentials stored as a function of time in the output database file. Nodes can be removed for the current problem. When the nodal output variables on the output database file are on nodes that are not present in the mesh for the current analysis, they are ignored.

You must specify the name of the output database file that contains the required nodal output variables as well as the nodal output label (NT, NNC, or EPOT) to identify the field that is being read. See Defining Fields Using Nodal Scalar Output Values from a User-Specified Output Database File.

If both models contain part and assembly definitions, the part (.prt) files from both analyses are required to transfer nodal results from the original analysis to the current analysis. If the original model is defined in terms of an assembly of part instances, the current analysis must be as well. The part instance names and local node numbers must be the same in both analyses for the nodes at which nodal results are transferred.

In some geotechnical applications a fully coupled pore fluid diffusion and stress analysis can be approximated by a sequentially coupled approach that consists of two parts:

1. A purely pore fluid flow analysis that computes the pore fluid pressure distribution in the porous medium without accounting for the deformation in the solid skeleton.
2. A pure stress analysis that only computes the deformation of the solid skeleton, taking into account the effects of the pore fluid pressure field computed in the first part.

In such an approach, you must transfer a known pore fluid pressure field (computed in the first part of the sequential workflow) into a stress analysis (the current analysis, which is the second part of the sequential workflow).

To define the pore fluid pressure field at different times in the current analysis, you must first associate the pore fluid pressure field with a specific field variable (see Pore Fluid Pressure). Subsequently, you can use any of the available methods to read or define predefined fields to include the known pore pressure field in the stress analysis.