Thermal / Structural Collaboration

Thermal to Structural Translation

From Patran Thermal, the steps are:
The thermal analyst completes the transient thermal analyses and provides temperatures for each time step in the form of "nodal results files." These nodal results files (nrf) are binary files containing node and temperature data. The files are not directly usable by the structural analyst because the structural and thermal models are normally, if not always, different (different mesh densities, for example). Therefore an interpolation procedure must be run in order to transfer the thermal results onto the structural model. An outline of the steps involved is given below:

1. Obtain nodal results files from the thermal analysis.
2. Obtain a Patran thermal neutral file describing the nodes and elements of the thermal model.
3. Generate a Patran structural neutral file describing the nodes and elements of the structural model.
4. Execute the Patran Patq utility to interpolate the temperatures from the thermal model to the structural model. Inputs are the thermal and structural neutral files and the nodal results file. Output is a Patran neutral file containing the interpolated temperatures at each of the structural nodes (one output file for each nodal results input file). Model Center can drive this step.
5. Either import the structural temperature neutral files into Patran and create load cases corresponding to each thermal analysis time step, or write a translator to convert the temperature neutral files into Nastran bulk data TEMP entries to include in a Nastran bulk data file of the model. Model Center can drive this step.
6. Generate Nastran files for each load case and execute Nastran. Model Center can drive this step.
7. Either import Nastran results into Patran and evaluate structural responses for each time step to determine the worst case, or use Model Center to parse the Nastran results to find and display the worst case.

From Thermal Desktop, the steps are:

1. In Thermal Desktop, do Thermal…Export…Temps to NASTRAN model. You must have an existing NASTRAN model in the same location and in the same units as your Thermal Desktop model. (Notes: use Thermal…Preferences to set model to same units as NASTRAN model (e.g., mm)). Outside, within Windows, change NASTRAN node file extension to .dat if necessary. NASTRAN model must have BEGIN BULK card, can have other info as well (temps, header, etc)).

   In Patran:

2. Import thermal exported file into PATRAN and make plots of each nodal results file. (It is helpful to verify these against thermal plots for correct interpolation).
3. Create Fields: Use the result contour plots to create fields for each set of thermal data.
4. Create Thermal Load Sets: Use the fields to create a temperature load for each case.
5. Create Load Cases: Create load cases for each thermal case.