You may need to combine two or more separate models if you are working on a portion of a model while another person works on a different portion of the same model. Or perhaps you have subdivided a large modeling task into smaller separate tasks, which created several separate models. One way to combine these models would be to merge all the input (commands) together, if you have kept copies of the input files. Conflicts may result with this method, however, because entities on different files may share the same number, material properties may overlap, etc.

One alternative is to use the CDWRITE command to write data to an ASCII file. You can then use the CDREAD command to read the data back in. The advantage of this method is that the combination of the write and read operations takes care of conflicting data by automatically writing appropriate NUMOFF commands to each file that is produced.

When these files are read in, the NUMOFF commands prevent conflicts in data numbers by offsetting existing data numbers. The data that is being read in retains its original numbering. You can use the NUMCMP command to remove gaps in numbering that can result from these NUMOFF operations.

On large models, you can save time by writing out only the portion of the models that you wish to combine. For instance, with the CDWRITE operation, you have the capability of writing out only the solid model information or only the database information. The database information consists of the finite element model without any solid model or solid model loading information. If you are planning on combining two unmeshed solid models, consider saving only the solid model information with the CDWRITE operation. You can then use the CDREAD operation to read in the solid model files.