MSC Nastran > Read Input File > 5.2 Data Translated from the NASTRAN Input File
   
5.2 Data Translated from the NASTRAN Input File
The following sections describe which specific MD Nastran entry types can currently be read into Patran.
The MD Nastran entries described in this document are the only entries read when importing a NASTRAN input file into Patran. All non-supported entries will be sent to the appropriate Direct Text Input data box for this job. When errors occur during the import of a supported entry type, the entry being processed may or may not be imported, depending on the severity of the problem encountered. An error message will be presented regardless of whether or not the offending entry is actually imported.
Any references from supported entries to entries that were not imported (either due to not being a supported entry type or due to serious import errors) will still be attempted. If this reference is required in Patran for the entry currently being processed, it too will fail to import. For example, if there is a serious error on a GRID entry which causes it to not imported, then all elements attached to that GRID will also fail to import.
Partial Decks
This Patran function can read incomplete MD Nastran files (except where explicitly noted). However, if the BEGIN BULK command is missing, the program can get confused when trying to determine if a particular entry belongs to the case control or bulk data. If you experience any difficulties importing a file that does not have a BEGIN BULK command, add one to the top of the file. This should avoid any such confusion.
Unrecognized Data
Data in the MD Nastran input deck that is not recognized by Patran, including comments are placed in the reject file. These rejected cards are also placed into the Direct Text Input (DTI) text boxes. If you turn ON the ability to write DTI into the various portions of the MD Nastran input deck, the rejected cards will be placed back into the input deck when it is written out again. Note that decks with large amounts of rejected cards and comments may place an unacceptable amount of data in these text boxes. If this is the case, you can limit the amount of data by setting the environment variable:
Coordinate Systems
The following coordinate system definitions can be read into Patran.
Command
Comments
CORD1C
CORD1R
CORD1S
References to the GRIDs on these entries are lost. The locations of the referenced GRIDs are extracted, and those locations are used to create the Patran definition.
CORD2C
CORD2R
CORD2S
References to RIDs are lost. The specified locations are converted to global cartesian for use in the Patran definitions.
The original B and C points are not retained. Their values are recomputed when a new NASTRAN input file is created. The definition will be equivalent, but not identical.
Referential Integrity
Coordinate systems and GRIDs which are referenced as part of a CORD definition must be in the same input file. If these are not found in the input file, the definition will be rejected.
References to coordinate frames other than for new coordinate frame definitions can be resolved with coordinate frames previously found in the Patran database.
Chaining
Due to limitations in the Patran definitions of coordinate systems, chained definitions (definitions based on other coordinate systems or grids) are modified during import. The resulting definitions are equivalent in global space, but are based on global cartesian coordinates rather than GRID references or coordinate locations in other systems. This change is carried through when a new NASTRAN input file is created. All coordinate systems will be created using CORD2 type definitions, and they will all reference global cartesian coordinates. These definitions will be different from, but equivalent to, the original definitions.
Grids and SPOINTs
The MD Nastran GRID entry is read fully, except the SEID field. The CD and CP references are both maintained. The PS data is used to create a constraint set. The details of the created load set are defined in the load set import section.
GRDSET data is merged into the GRID data during import. The data will be retained, but will appear directly on the GRID entry when a new NASTRAN input file is generated.
SPOINTs
SPOINTs are treated as GRIDs at the global origin. They are assumed to have their GRID CD and CP fields set to the basic system, and their PS field is set to permanently constrain degrees-of-freedom 2 through 6.
Referential Integrity
Coordinate frames referenced in the CP field must exist in the same input file. Coordinate frames referenced on the CD field can exist in either the same input file, or the Patran database prior to the import.
Elements and Element Properties
The following MD Nastran elements and element properties can be read into Patran.
Element
Property
Property Set Name
Comments
CBAR
PBAR
pbar.<pid>
Orientation and offset vectors are re-defined in global cartesian during import.
(See BAROR comments below.)
 
 
PBARL
pbarl.<pid>
 
CBARAO
 
 
New property sets are created for each occurrence of a CBAR entry referenced by a CBARAO entry
CBEAM
 
 
Orientation and offset vectors are re-defined in global cartesian during import.
(See BEAMOR comments below.)
PBEAM
pbeam.<pid>
 
PBEAML
pbeaml.<pid>
 
PBCOMP
pbcomp.<pid>
The MD Nastran documentation describes how the section data is used to create a complete set of lumped areas. The data imported into Patran is fully expanded, and therefore, is different from the data in the original input file. This definition is, however, fully equivalent to the original.
The SO field is not currently supported. A YES is provided automatically when a new NASTRAN input file is created.
Only the lumped areas definition is understood, If a uniform cross section is defined here, it will be converted to a lumped area definition, but no lumped areas will be defined.
CBEND
 
 
 
Patran only understands the GEOM = 1 orientation data. If other definitions are found, a vector will be computed to convert the definition to the GEOM = 1 format. If a GRID was referenced for GEOM other than 1, that reference will be lost. For the same reasons, the THETAB and RB data will also be lost since that data is not used for GEOM = 1 definitions.
Orientation and offset vectors are re-defined in global cartesian during import.
PBEND
pbend_g.<pid>
If standard cross section properties are found on the PBEND entry
pbend_p.<pid>
If the alternate format of the PBEND is used to define a pipe cross section.
CBUSH
PBUSH
pbush.<pid>
 
 
 
pbush_g.<pid>
The grounded form of the PBUSH
 
PBUSHT
pbusht_1D.<pid>
 
CDAMP1
PDAMP
pdamp.<pid>
For dampers connecting 2 GRIDs.
pdamp_g.<pid>
For grounded dampers attached to a single GRID.
CDAMP2
 
cdamp2
For dampers connecting 2 GRIDs.
cdamp2_g
For grounded dampers attached to a single GRID.
CDAMP3
PDAMP
 
Treated identical to the CDAMP1 and CDAMP2 elements with the degree-of-freedom fields set to 1 (UX).
CDAMP4
 
CELAS1
PELAS
pelas.<pid>
For springs connecting 2 GRIDs.
pelas_g.<pid>
For grounded springs attached to a single GRID.
CELAS2
 
celas2
For springs connecting 2 GRIDs.
celas2_g
For grounded springs attached to a single GRID.
CELAS3
PELAS
 
Treated identical to the CELAS1 and CELAS2 elements with the degree-of-freedom fields set to 1 (UX).
CELAS4
 
CGAP
 
 
Orientation and offset vectors are re-defined in global cartesian during import.
PGAP
pgap.<pid>
For non-adaptive definitions on the PGAP entry.
pgap_a.<pid>
For adaptive definitions on the PGAP entry.
CHBDYG
CHBDYP
PHBDY
 
Note: The BDYOR command that may contain default values for CHBDY elements is not currently supported.
CHEXA
PSOLID
psolid.<pid>
 
CMASS1
PMASS
pmass.<pid>
For masses connecting 2 GRIDs.
pmass_g.<pid>
For masses attached to a single GRID.
CMASS2
 
cmass2
For masses connecting 2 GRIDs.
cmass2_g
For masses attached to a single GRID.
CMASS3
PMASS
 
Treated identical to the CMASS1 and CMASS2 elements with the degree-of-freedom fields set to 1 (UX).
CMASS4
 
CONM1
 
conm1
 
CONM2
 
conm2
 
CONROD
 
conrod
 
CPENTA
PSOLID
psolid.<pid>
 
CQUAD4
PSHELL
pshell.<pid>
(See PSHELL comments below.)
PCOMP
pcomp.<pid>
A new material named pcomp.<pid> will be created and referenced.
The SB and FT fields are currently not read.
CQUAD8
PSHELL
pshell.<pid>
(See PSHELL comments below.)
PCOMP
pcomp.<pid>
A new material named pcomp.<pid> will be created and referenced.
The SB and FT fields are currently not read.
CQUADR
PSHELL
pshellr.<pid>
(See PSHELL comments below.)
PCOMP
pcompr.<pid>
A new material named pcomp.<pid> will be created and referenced.
The SB and FT fields are currently not read.
CROD
PROD
prod.<pid>
 
CSHEAR
PSHEAR
pshear.<pid>
 
CTETRA
PSOLID
psolid.<pid>
 
CTRIA3
PSHELL
pshell.<pid>
(See PSHELL comments below.)
PCOMP
pcomp.<pid>
A new material named pcomp.<pid> will be created and referenced.
The SB and FT fields are currently not read.
CTRIA6
PSHELL
pshell.<pid>
(See PSHELL comments below.)
PCOMP
pcomp.<pid>
A new material named pcomp.<pid> will be created and referenced.
The SB and FT fields are currently not read.
CTRIAR
PSHELL
pshellr.<pid>
(See PSHELL comments below.)
PCOMP
pcompr.<pid>
A new material named pcomp.<pid> will be created and referenced.
The SB and FT fields are currently not read.
CTRIAX6
 
ctriax6
 
CTUBE
PTUBE
ptube.<pid>
Tapered tubes are converted to an equivalent constant section definition.
CVISC
PVISC
pvisc.<pid>
 
PLOTEL
 
 
Creates the connectivity only. These elements are not assigned to any property set region.
PLOTEL entries will not be written when a new input file is created.
MBOLTUS
 
 
Defines a bolt in the form of an Overclosure MPC.
Higher order elements (CQUAD8, CTRIA6, CTRIAX6, CHEXA, CPENTA, CTETRA) will generate linear elements in Patran if none of the mid-edge nodes are specified.
PSHELL Properties
PSHELL properties can be imported as any one of five Patran property types. The MID1, MID2, MID3, 12I/T3, and TS/T property fields are used to determine which one to choose. If MID2 is -1 and MID3 is 0, then a Plane Strain property set is used. If MID2 and MID3 are both 0, then a Membrane property set is chosen. If MID1 and MID3 are 0, then a Bending property set is used. If MID1, MID2, and MID3 are all the same, and the MD Nastran defaults are used for 12I/T3 and TS/T, then a Homogeneous property set is used. If all else fails, then an Equivalent Section property set is chosen.
BAROR and BEAMOR Definitions
The BAROR and BEAMOR data is merged onto the CBAR and CBEAM entries using the proper MD Nastran conventions. The data is treated as if it had originally been defined on the CBAR and CBEAM entries. When a new NASTRAN input file is created, the data will remain with the CBAR and CBEAM entries. No BAROR or BEAMOR entries are generated.
Fields
If a field is required to store varying data, the field will have the same name as the property set, with the name of the specific property word appended to it. For example, if property set “pshell.101” has a varying thickness, the field will be named “pshell.101.Thickness”.
Referential Integrity
Nodes and coordinate frames referenced on elements or element properties must exist, but they do not need to be in the input file. They could also have been defined in the Patran database prior to the import.
If a material is referenced, but can not be found, a new material with no properties will be created. A message will be issued indicating the creation of this material.
If an element property set is referenced, but can not be found, a new property set with no properties will be created. A message will be issued indicating the creation of this property set.
Set Name Extensions
In some cases, the data found on the element can not be defined in Patran in a single property set. In those cases, multiple property sets will be created to define the distinct definitions. The table below defines extensions to the Property Set Names shown in the previous table. If the values on the specified field changes, a new property set with the indicated extension will be created.
If all elements which reference a single PID can be stored in a single property set, then no extension will be added to the Property Set Name.
Element
Field
Extension
Comments
CBAR
PA
PB
.pa<PA>
.pb<PB>
 
CBEAM
SA
SB
PA
PB
.sa<SA>
.sb<SB>
.pa<PA>
.pb<PB>
 
CDAMP1, CDAMP2,
CELAS1, CELAS2,
CMASS1, CMASS2
C1
C2
.ca<C1>
.cb<C2>
 
CDAMP3, CDAMP4,
CELAS3, CELAS4,
CMASS3, CMASS4
C1
C2
.ca1
.cb1
These are automatically treated as component 1 (X translation).
CGAP, CONM1, CONM2
CID
.c<CID>
 
CONROD, CTRIAX6
MID
.m<MID>
 
CQUAD4, CQUAD8,
CQUADR, CTRIA3,
CTRIA6, CTRIAR
MCID
.c<MCID>
 
Materials
The following MD Nastran material definitions can be read into Patran.
Material Type
Material Name
Comments
CREEP
 
 
MAT1
mat1.<mid>
The MCSID field is not currently supported.
If the G field is blank in the input file, the MD Nastran default value will be filled in during import.
MATT1
 
 
MAT2
mat2.<mid>
The MCSID field is not currently supported.
MATT2
 
 
MAT3
mat3.<mid>
 
MATT3
 
 
MAT4
 
 
MATT4
 
 
MAT5
 
 
MATT5
 
 
MAT8
mat8.<mid>
 
MAT9
mat9.<mid>
 
MATT9
 
 
MPCs
The following MD Nastran MPC and rigid element definitions can be read into Patran.
Card Type
MPC Type
Comments
MPC
Explicit
Unique MPC IDs will be assigned to these entities.
Since Patran uses a slightly different basis MPC equation, the equation coefficients (Ai) will probably be scaled by a constant multiplier during import. The resulting equation will be equivalent, but not necessarily identical to the original definition in the NASTRAN input file.
RBAR
RBAR
 
RBE1
RBE1
 
RBE2
RBE2
 
Fixed
 
RBE3
RBE3
 
RROD
RROD
 
RSPLINE
RSPLINE
 
RSSCON
RSSCON
 
RTRPLT
RTRPLT
 
MPCs in Patran are treated as elements and are not associated to load cases. As a result, all SUBCASE related data is lost. The MPCs are simply imported into the model and are no longer associated to a specific load case.
MPCs can reference SPOINTs instead of GRIDs. If this is detected, the corresponding component field will be set to 1 (UX) to be consistent with the import of SPOINTs.
The MPCADD command is not read since the MPCs are simply imported and no associated to a load case. The SID references on the MPC entry are also lost for the same reason. New MPC IDs are assigned to these elements during import.
Load Sets
The following MD Nastran Loads and Boundary Condition definitions can be read into Patran.
Card Type
LBC Set Name
Comments
FORCE
force.<sid>
 
GRAV
grav.<sid>
 
MOMENT
moment.<sid>
 
PLOAD1
pload1.<sid>
Only PLOAD1s applied to the entire length of an element can be read. If a load is applied only to a portion of an element, the load will be ignored, and a message will be presented indicating the problem.
PLOAD2
pload2.<sid>
 
PLOAD4
pload4.<sid>
Only pressure loads normal to the surface can be imported. If a surface traction is detected, it will be ignored, and a message will be presented indicating the problem.
PLOADX1
ploadx1.<sid>
 
CONV
conv.<pid>
 
PCONV
 
 
CONVM
convm.<pid>
 
PCONVM
 
 
QBDYi
qbdyi.<pid>
 
QVECT
qvect.<pid>
 
QVOL
qvol.<pid>
 
RADBC
radbc.<pid>
 
RADCAV
radcav.<pid>
Note: ELEAMB field is not supported by Patran. The ambient element is added to the application region.
RADM
 
 
RADMT
 
 
RFORCE
rforce.<sid>
If the G point is not at the origin of the referenced CID, a new CID will be created and referenced.
The METHOD field is not read. It is automatically set to 1 when writing a new file.
SLOAD
sload.<pid>
 
TEMP
temp.<sid>
 
TEMPP1
tempp1.<sid>
Only the average temperature and effective linear gradient data fields are used. The specified temperatures at the Z1 and Z2 locations are ignored.
TEMPRB
temprb.<sid>
Only the average temperature and effective linear gradient data fields are used. The specified temperatures at the stress recovery locations are ignored.
grid#
grid.ps
 
SPC
spc.<sid>
 
SPCADD
 
 
SPC1
spc1.<sid>
 
SPCD
spcd.<sid>
The required SPC or SPC1 entries for the same Degree-of-Freedom are removed from the load case when a SPCD is found. They will automatically be re-generated when a new input file is created.
VIEW
 
 
VIEW3D
 
 
Fields
If a field is required to store varying data, the field will have the same name as the load set, with the name of the specific data word appended to it. For example, if load set “force.101” has a varying force magnitude, the field will be named “force.101.Force”.
Load cases are created in Patran from the SUBCASE definitions in the NASTRAN input file. Load sets not referenced by a SUBCASE definition are created as load sets in Patran, but are not associated to a load case. Load sets defined above the first SUBCASE command, plus any permanent single point constraint sets from the GRID entries, are associated to all load cases created during this import. If there is no case control data, then load sets will be created, but they will not be assigned to any load cases.
The SPCADD and LOAD entries are used in creating load cases in Patran, but the SID of these entries is lost. The SIDs on the individual SPCx, FORCE, MOMENT, GRAV, PLOADx, RFORCE, and TEMPx entries are used in creating the names of the load sets.
The name for the created load cases is derived from the subtitle of the SUBCASE. This is done for consistency with the forward PAT3NAS translation.
A job is created during the import. The name of the created job is the basename of the file being read.
MD Nastran allows load sets to be referenced in multiple places with different scale factors. This is not possible in Patran. Therefore, in some cases, multiple copies of the same load set need to be created with the only difference being the scale factor. The name of these load sets are modified to include the subcase ID to create unique names.
TABLES
The following table types are supported during import of a NASTRAN input file. Note that some forms of the table commands are converted to an equivalent version supported by Patran.
Card Type
Field Name
Comments
TABLED1
Field.<tid>
 
TABLED2
Field.<tid>
Converted to an equivalent TABLED1 when read into Patran by NIFIMP.
TABLED3
Field.<tid>
Converted to an equivalent TABLED1 when read into Patran by NIFIMP.
TABLEM1
Field.<tid>
 
TABLEM2
Field.<tid>
Converted to an equivalent TABLEM1 when read into Patran by NIFIMP.
TABLEM3
Field.<tid>
Converted to an equivalent TABLEM1 when read into Patran by NIFIMP.
SOL 600 entries
Note: A
Additional entries specific to SOL 600 can be read into Patran. For more details see MD Nastran Implicit Nonlinear (SOL 600), 14.