NASTRAN – Interface

Abbildung 1

With command „NASTRAN“ the following NASTRAN-records (see „MSC/NASTRAN Version 70, Quick Reference Guide“) can be written to a file, respectively elements can be read from a NASTRAN file.

Following dialog shows the available options:

New file tile: Default is the current project title; this button allows selecting another title for the NASTRAN file.

Extension: The extension for the NASTRAN file can be given in the input field, default is .dat.

Write only geometry data: With this option set, only nodes, elements and coordinate systems are written to the file.

Different files: With this option set, the geometry data, the property data and the load data are written to different files with extensions .dat, .nprop, .nload.

Node constraints as SPC1 records: With this option set, SPC1 records are generated for single point constraints, else these constraints are stored as parameters CD and PS in the GRID records.

Transfer forces into global coordinates: With this option set, any forces (displacements) that are defined in local coordinate systems are transformed into the global coordinate system before written into the file.

Check assignments: With this option set the following controls as with command „CheckNASTRAN“ are executed:

Mechanical type ID: All elements are checked, whether the assigned mechanical type ID is compatible with the geometrical element type (element with wrong assignments are stored in the element selection Set 1).

Property-record: All elements are checked whether a correct property type for the property record is assigned (elements with wrong assignments are stored in the element selection Set 2).

Cross-section: All elements are checked, whether a correct cross-section type with additional element parameters is assigned (elements with wrong assignments are stored in the element selection Set 2).

Material: It is checked, whether all used material IDs are defined.

With button „Write“ a NASTRAN input file is created. The data for the NASTRAN file is read from the files „project.fes“ and „project.lqd“ where „project“ is the current file title of the project. Before reading these files it is asked, whether the files should be updated with data in memory. The answer must be „yes“, if any new defined data is not yet saved to file.

With button „Read“, node data, element data and coordinate systems are read from the given NASTRAN file. Property records and load records are not read.

NASTRAN records

Following is described how the different MAKROS data is translated to NASTRAN records. The interface will be expanded on request.

Node data, single-point constraints

Node data is stored in GRID records. If there are any constraints defined for individual nodes (command “Constraints„) these constraints are optionally stored in the GRID record or as SPC1 records.

Elements and element properties (cross-sections)

The translation of MAKROS elements to the different types of NASTRAN elements is done on the basis of assigned mechanical type IDs (mtype).

An element record defines NASTRAN elements and an associated property record in the NASTSRAN input file. The NASTRAN element record stores the element ID, the IDs of connected grid points, the ID of the associated property record and with some element types additional data as for example the thickness of the element.

The specifications for the property record and for additional data if required are defined with the command „Cross-section“. Following we use the term „cross-section“ for all this kind of data independent whether it affects the property or the element record. Different kinds of cross-sections are distinguished by a cross-section type ID (qtype). Each cross-section consists of a cross-section ID, a type ID, a material ID and a number of cross-section values. The material number is stored in the property record while the cross-section values are stored in the property record or the element record depending on the used type ID.

The cross-sections that are determined for the property records must be assigned a type ID that is 1000 greater than the mechanical type ID of the corresponding elements (qtype = mtype + 1000) while cross-sections that are determined for the element record must get the same type ID as the corresponding elements (qtype = mtype).

Following table shows which mechanical type ID (mtype, column 1) must be assigned to MAKROS elements to get the NASTRAN elements shown in column 3 with property records shown in column 4. For example assigning mechanical type ID 11 to an element of geometrical type 42 will lead to a NASTRAN record CQUAD8 with property record PLPLANE. In the following table column 2 shows which MAKROS elements may be used for different NASTRAN element records. Column 5 shows the number of cross-section values that must be given for the property record while column 6 shows the number of cross-section values that must be given for additional data in the element record. If the numbers in column 6 are enclosed in brackets the cross-section with type ID qtype = mtype is optionally, for example the thickness of membrane elements can also be given in the cross-sections for the property records if the thickness is the same in all nodes.

Assignment of NASTRAN elements to MAKROS elements

mtype	MAKROS- Type	NASTRAN- Element-Record	NASTRAN- Property-Record	Number of Property values	Number of additional Element values	Remarks
1	2	3	4	5	6	7
11	30	CTRIA3	PLPLANE	2	[2 o. 6]	6) ,7) ,8)
11	32	CTRIA6	²	²	²	², ²
11	40	CQUAD4	²	²	²	², ²
11	42	CQUAD8	²	²	²	², ²
13	40, 42, 46	CQUAD	²	²	-	²
14	30, 32	CTRIAX	²	²	-	²
14	40, 42, 46	CQUADX	²	²	-	²
15	30, 32	CTRIAX6	-	-	1	², 11)
21	30	CTRIA3	PSHELL	1 o. 9	[2 o. 6]	6), 7), 9)
21	32	CTRIA6	²	²	²	², ²
21	40	CQUAD4	²	²	²	², ²
21	42	CQUAD8	²	²	²	², ²
22	30	CTRIAR	²	²	²	²
22	40	CQUADR	²	²	²	²
31	30	CTRIA3	PCOMP	variable	²	6), 7) , 13), 3)
31	32	CTRIA6	²	²	²	², ²
31	40	CQUAD4	²	²	²	², ²
31	42	CQUAD8	²	²	²	², ²
32	30	CTRIAR	²	²	²	²
32	40	CQUADR	²	²	²	²
41	40	CSHEAR	PSHEAR	4	-
60	60, 62	CPENTA	PLSOLID	1	-	8)
60	70, 72	CTETRA	„	„	-
60	80, 82	CHEXA	„	„	-
61	60, 62	CPENTA	PSOLID	5	-	22)
61	70, 72	CTETRA	„	„	-
61	80, 82	CHEXA	„	„	-
101	20	CONROD	-	-	4
102	20	CROD	PROD	4	-
103	20, 1	CELAS1	PELAS	3	2	12) , 20)
104	20, 1	CELAS2	-	-	5	„ „
105	20, 1	CDAMP1	PDAMP	1	2	„ „
106	20, 1	CDAMP2	-	-	3	„ „
108	20	CTUBE	PTUBE	4	-
110	20	CBAR	PBAR	17	3 o. 6 o. 12	16), 21)
111	20	²	²	„	3 o. 6 o. 12	², 17)
112	20	²	²	„	2	², ², 18)
113	20	²	PBARL	variable	3 o. 6 o. 12	², 10)
114	20	²	²	„	3 o. 6 o. 12	² , 17)
115	20	²	²	„	2	², ² , 18)
120	20	CBEAM	PBEAM	variable	4 o. 6 o. 12 o. 14	16), 3)
121	20	²	²	„	4 o. 6 o. 12 o. 14	², 17)
122	20	²	²	„	2	², ², 18)
123	20	²	PBCOMP	variable	14	²
124	20	²	²	„	14	², 17)
125	20	²	²	„	2	², ², 18)
126	20	²	PBEAML	variable	14	², 10)
127	20	²	²	„	14	², 17)
128	20	²	²	„	2	², ², 18)
130	20	CGAP	PGAP	10	4
131	20	²	²	²	-	19)
140	20	CVISC	PVISC	2	-
150	20	RBAR	-	-	4
201	1	CONM1	-	-	22
202	1	CONM2	-	-	11
210	-	MPC	-	-	variable	14)
211	20	²	-	-	Variable	15)

Remarks:

1) To elements that have the same cross-section values can be assigned the same cross-section ID (option Element selection in the command „Cross-section“).

2) Cross-section values are written into the property record (after the material ID) respectively into the element record in the same order as given, missing values at the end are set to zero.

3) Values for fields in the NASTRAN records that should remain blank must be given as –99 or as 0. Cross-section values –99 or 0 leave the corresponding field in the NASTRAN record blank.

4) For property records always 6 values for the first line and 8 values for the following lines must be given independent of the type of record. For fields that are blank in the record, the value –99 or 0 must be given in the corresponding cross-section. In case the property record contains no material ID, 7 values must be given for the first line (for example PCOMP, PGAP).

5) For some fields that contain no numerical data a special numerical code is given in the following. If no code is given, these fields must be edited afterwards.

6) mtype = 11-32: Additional values for the element records of CTRIAx and CQUADx are values for THETA, ZOFFS and T1 – T4 (thickness). If no cross-sections for these elements ( qtype = 11 – 32 ) exist, the corresponding fields are left blank. If only 2 values are given in the cross-section, these are used for THETA and ZOFFS, if more values are given, the first 2 values are used for THETA and ZOFFS, remaining values are used for T1 – T4.

7) mtype = 11,21,31: Which NASTRAN element record (CTRIA3 – CQUAD8) is written for mtype = 11, 21, 31 depends on the number of nodes of the given MAKROS element.

8) mtype = 11-50,60: For parameter STR in the property records PLPLANE and PLSOLID the values 0 for „GAUS“ and 1 for „GRID“ must be given.

9) mtype = 21,22: If the cross-section for the property record PSHELL (qtype = 1021, 1022) contains only 1 value, this value is used for parameter T. Parameters MID2 and MID3 are set to MID1 (material ID), the remaining fields are left blank.

10) mtype = 113-115,126-128: For parameter TYPE in records PBARL and PBEAML the numerical code 0 – 18 is translated as follows: 0 = ROD, 1 = TUBE, 2 = L, 3 = I, 4 = CHAN, 5 = T, 6 = BOX, 7 = BAR, 8 = CROSS, 9 = H, 10 = T1, 11 = I1, 12 = CHAN1, 13 = Z, 14 = CHAN2, 15 = T2, 16 = BOX1, 17 = HEXA, 18 = HAT.

11) mtype = 15: For record CTRIAX6 the corresponding cross-section (qtype = 15) must contain the material ID and 1 value for the parameter TH.

12) mtype = 103-106: Additional element data for the records CELAS1, CDAMP1 are the parameters C1, C2, for record CELAS2 the parameters K, C1, C3, GE, S and for record CDAMP2 the parameters B, C1, C2. If the MAKROS element is a point element (gtype = 1), the fields for G2 and C2 are left blank (NASTRAN scalar element).

13) mtype = 31,32: The numerical code for parameter FT in the record PCOMP is as follows: 1 = HILL, 2 = HOFF, 3 = TSAI, 4 = STRN, 0 leaves the field blank. For LAM > 0 „SYM“ and for SOUTi > 0 „YES“ is set.

14) mtype = 210: With mtype = 210 no element but only a cross-section with type ID 210 has to be defined. The values of the cross-section are written into a record of type MPC, the material ID is not used.

14) mtype = 211: With mtype = 211 the nodes of the line element (< = 5 nodes) are use as parameters G1 – G5 in a MPC record, the values for Ci and Ai must be given in a cross-section of type 211.

16) mtype = 110-115,120-128: Cross-sections with additional element data are equally interpreted for element types CBAR and CBEAM. With CBAR the value for field 9 and for parameters SA and SB must be given as 0 or –99. If only 3 (4) values are given, these are used for X1, X2, X3, (BIT), with 6 values given also PA, PB are set and with 12 (14) values given the last values are used for parameters W1A – W3B and SA and SB.

17) mtype = 111,112,114,115,121,122,124,125,127,128: The alternative format of records CBAR respectively CBEAM is used where the 3. node of the element is used for parameter CO, values for X1- X3 in the cross-section are not used.

18) mtype = 112,115,122,125,128: The vector from node 4 towards node 1 of the element is used for the parameters W1A – W3A, and the vector from node 5 towards node 2 of the element is used for the parameters W1B – W3B (the fields remain blank, if nodes 4 respectively 5 are zero). In the corresponding cross-section only values for parameters PA and PB must be given.

19) mtype = 131: The alternative format of record CGAP is used where 3. node of the element is used as a parameter GO, CID is set to zero.

20) mtype = 103-106: Only 1 property cross-section is stored per record.

21) mtyp = 110: To CBAR elements an additional cross-section with ID = 2110 can be assigned that contains 4-6 values. This cross-section is stored as CBARAO record. For parameter SCALE 1 for LE and 2 for FR has to be given. With SCALE = 1 and 4 cross-section values these are written as SCALE, NTPS, X1 and DELTAX, else the given values are written as SCALE and X1-X6.

22) mtyp = 61: For FCTN not zero FLUID is set..

Material data

Material data is defined with command „Material“. Each record contains a material ID, a material type ID and a variable number of material values. The material type ID (matype) is used to distinguish different NASTRAN material records as shown in following table:

matype	NASTRAN	matype	NASTRAN	matype	NASTRAN
1 4 9	MAT1 MAT4 MAT9	2 5 10	MAT2 MAT5 MAT10	3 8 11	MAT3 MAT8 MATHP

The material values are written into the NASTRAN record in the same order as given. For the first line 7 values and for following lines 8 values must be given independent of the record type and the number of values in the lines of the record. For fields that are blank in the record, the value 0 or –99 must be given.

Node forces, moments or displacements

Node vectors are defined with the command „Node forces” With a type ID (ltype) different types of vectors are distinguished as shown in following table:

ltype	Vector type	NASTRAN-Record
0 1 2 3 4 5	Force vector Moment vector Displacement vector Rotation vector Displacement vector Rotation vector	FORCE MOMENT SPC SPC SPCD SPCD

The vectors may be defined in a local coordinate system. In the NASTRAN dialog box can be specified that vectors defined in local coordinate systems should be transformed to global coordinates before written to the NASTRAN file. Written into the NASTRAN records are the load set ID, the node ID, the ID of the local coordinate system, the scale factor and 3 vector components. With command „Surface loads“ distributed loads can be defined that are immediately converted to statically equivalent node forces. These forces are also written into records of type FORCE.

For ltype = 2 and 3 records of type SPC and for ltype = 4 and 5 records of type SPCD are written, that means the vectors are interpreted as enforced displacement vectors.

Single point constraints

Single point constraints are defined using command „Constraints“, they are alternatively written into the GRID records or SPC1 records. Enforced displacements (NASTRAN records SPC and SPCD) can be defined with command „Node forces” (see above). Multi point constraints are defined as a cross-section with type ID 210 or 211.

Element loads

Element loads are defined with command „Element loads“. With a load type ID (latype) different NASTRAN records are distinguished as shown in following table:

latype	NASTRAN-Record	Number of values
10 11 12 14	PLOAD PLOAD1 PLOAD2 PLOAD4	1 6 1 4 (10)

In the dialog only the following data must be given: the index, the load set ID, the load type ID and the load values, these must be given in the input field for central load components (EFLAG = 1, GFLAG = 0). The other input fields are not used for NASTRAN data. As load specifications the following values must be given for the NASTRAN records:

latype = 10: 1 Value for P

= 11: Codes for TYPE, SCALE and 4 values for X1, P1, X2, P2

= 12: 1 Value for P

= 14: Values for P1 – P4 and with solid elements values for G1, G3, CID, N1 – N3

For PLOAD the corner nodes of the selected elements are used. The sign of P must be chosen to correspond to the orientation of the element. With solid elements these surfaces are loaded whose corner nodes are all contained in the given node selection.

With PLOAD1 first a code for the parameter TYPE must be given. The code is 1 – 12 for the following character strings: FX, FY, FZ, FXE, FYE, FZE, MX, MY, MZ, MXE, MYE, MZE. Next the code for parameter SCALE must be given, the numbers 1 – 4 stand for LE, FR, LEPR, FRPR.

If with latype = 14 a node selection is given, the nodes for the parameters G1 and G3 of the record PLOAD4 are automatically determined for solid elements, in this case given values for G1 and G3 must be zero.