MSC Nastran Interface

The strength assessment performed by the software LIMIT® incorporates a static and fatigue module to evaluate your structure. Base material as well as weld analysis can be accomplished using the commercial finite element code MSC Nastran (MSC.Software GmbH).

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Required import files for LIMIT

To allow a fatigue assessment of your structure using MSC Nastran (MSC Software), you have to have the .bdf or .dat to access the finite element model and the .op2 with all relevant result data.

Importing the .bdf-file into LIMIT-CAE

  • File ending must be .bdf or .dat
  • Nastran (.bdf; must be ‚sorted bulk data‘ in the ‚short‘ format!)

Coordinate systems

Nodes

  • Definition in the global coordinate system
  • Definition using CORD1R or CORD2R (RECTANGULAR)

Result data must exist in the global coordinate system (Solids) respectively in the default element coordinate system (shells).

Modifications for OP2-Output

  • sort: SORT1
  • Data format: REAL
  • Yield criteria: VONMISES
  • Position: BILIN (necessary for analyzing the gradient) or CORNER

e.g. STRESS(SORT1,REAL,VONMISES,CORNER)=ALL

Note: LIMIT® can average corner values of different elements, which is activated with the key *CENTER_STRESS

 

  • Geometry must be written to .op2-file:              PARAM, POST, -1

PARAM, OGEOM, YES

  • Please don‘t use:                                                    PARAM, PATVER, 2

Supported MSC Nastran (MSC Software) / OptiStruct (Altair) Versions in Release Package

  • MSC Nastran 2020.1
  • MSC Nastran 2019.0
  • MSC Nastran 2018.1
  • MSC Nastran 2016.1
  • MSC Nastran 2014.1

If you need a different version please contact our LIMIT® support.

Following elements can be analyzed

Solids:

  • CTETRA (4 nodes) (not suitable for stress assessment)
  • CPENTA (6 nodes) (less suitable for stress assessment)
  • CHEXA (8 nodes) (less suitable for stress assessment)
  • CTETRA (10 nodes) => stress gradient available
  • CPENTA (15 nodes) => stress gradient available
  • CHEXA (20 nodes) => stress gradient available

Shells:

  • CQUAD4
  • CQUAD8
  • CTRIA3
  • CTRIA6

For detailed information please refer to the MSC Nastran interface document (.pdf) or contact our LIMIT® support.