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Author Topic: Superimposed Pressure, avoid double bookkeeping with FEA loads  (Read 9761 times)


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During FEM import the element pressure loads are read in from the FEM. Then HyperSizer computes the average element pressure load for each component to superimpose the reaction moments (Mx, My) and shear loads (Qx, Qy), caused by the pressure, on the FEA loads. A problem exists if the pressure loads are also included in the FEA output, then the moments and shear loads will be double book-kept. To avoid this, a procedure to import the pressure loads into HyperSizer and remove them from the FEA analysis is described below.

1. Cut all PLOAD4 entries from the FEM file and paste them into a new text file (Filename.PLOAD4).
2. Save the Filename.PLOAD4 file in the same directory as the FEM bulk data file (Filename.bdf). Use an include statement in the FEM file to call the Filename.PLOAD4 file.
3. Comment-out the include statement to run FEA. This will prevent the FEA solution from returning any shear and moment loads resulting from the external pressure loads.
4. Uncomment-out the PLOAD include statement in the FEM for import into HyperSizer. See FEM Import:
5. Comment-out the PLOAD include statement in the FEM to iterate using HyperFEA. See HyperFEA:

By following the procedure outlined above, you will import the pressure loads into HyperSizer and the pressure induced moments and shear loads will be superimposed on the FEA loads during the analysis. To ensure these are not double book kept, you are removing the pressures from the FEA analysis so the FEA loads will not contain these pressure induced loads. It is important to note that this procedure should only be used for flat panels since curved panel react pressure load as hoop load and FEA is required to capture the pressure induced hoop load.