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Finite element interface to Simcenter Nastran
F.E. Interfaces
Finite element interface to Simcenter Nastran
Zencrack has an interface to Simcenter Nastran. This was formerly NX Nastran - the interface operates for NX Nastran 10, 11 and 12 and Simcenter Nastran. References across the website to Simcenter Nastran also apply to the supported NX Nastran versions 10, 11 and 12. A brief overview of the interface is given below.
The interface to Simcenter Nastran works via the .dat and .op2 files:
- An uncracked mesh must be supplied as a Simcenter Nastran .dat file. This may be generated in any suitable pre-processor.
- Zencrack then combines the uncracked mesh with data in the Zencrack input file to create a .dat file for the cracked component.
- The cracked mesh is submitted for analysis by Simcenter Nastran.
- When the Simcenter Nastran analysis is completed, Zencrack extracts results directly from the Simcenter Nastran output (.op2 file). The necessary results are generated via output requests that were created in the cracked mesh .inp file.
If crack growth is required, Zencrack carries out crack advancement using the results of the Simcenter Nastran analysis and generates a new .dat file for an advanced crack position. The new cracked mesh is then submitted for analysis. This process is shown schematically in the Zencrack flowchart.
This interface is able to calculate the following fracture mechanics parameters at nodes along the crack front:
- J-integrals via the Simcenter Nastran CRAKTP and VCEV options (only available for solution type SOL401).
- The stress intensity factors KI, KII and KIII calculated from nodal displacements (linear elastic isotropic materials) (available for solution types SOL101, SOL401).
The default analysis settings are to calculate j-integrals and displacement based stress intensity factors with the j-integral values used to drive crack growth. These defaults can be modified in the input file for a particular analysis.
The analysis results may be post-processed using the Zencrack GUI or utility programs provided with Zencrack. These allow visualisation of crack growth profiles, xy plotting and generation of a .csv files for use in a spreadsheet. In addition, all of the standard Simcenter Nastran output files are available for post-processing e.g. the .op2 file. During a crack growth analysis, the standard Simcenter Nastran files can be saved after successive Simcenter Nastran analyses to allow subsequent post-processing of multiple crack positions.
Note about Simcenter Nastran license requirements
Simcenter Nastran Desktop licenses include a checksum in input files created by their associated pre-processor which only allows execution of the file as generated by the pre-processor. This prevents uses of this type of input file with Zencrack since a fundamental part of the process is that Zencrack modifies the input file.
Enterprise licensing enables Simcenter Nastran to solve any valid Nastran input file from any pre-processor, including after modifications by Zencrack.
Simcenter Nastran can exist as a basic package with additional modules. Zencrack requires SOL101 as a minimum and Simcenter Nastran Multistep Nonlinear SOL401 for calculation of j-integrals.
If the "modified input file" requirement is satisfied and appropriate SOL types are available, Zencrack can use Simcenter Nastran as part of a stand-alone installation or when Simcenter Nastran is packaged within Simcenter3D, NX or Femap.
Licensing of Simcenter Nastran
The finite element package is not supplied with Zencrack and must be licensed from an appropriate supplier.
NX™ NASTRAN® software and Simcenter™ NASTRAN® software are trademarks or registered trademarks of Siemens Industry Software Inc., or its subsidiaries or affiliates, in the United States and in other countries.
Zentech International Limited is a member of the Technology Partner program of Siemens Digital Industries Software.
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