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C++ IO support for various FEM exchange file formats (NASTRAN BDF, DNV Sestra FEM)

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Table of Contents

  1. Supported FEM file formats
    1. Unit system considerations
    2. NASTRAN Bulk Data Format (BDF)
      1. BDF Cards supported
        1. Bulk Data
        2. Header Data
    3. DNV GL Seasam Input Interface File (FEM)
      1. FEM Cards supported
      2. Element Types in SESAM

Supported FEM file formats

Not all functionality defined for the exchange file formats is supported. The supported subset is currently mainly defined by the functionality supported in GLFrame rspt. the BMF file format.

More detailed information on supported functionality can be found in the according directories in the docs subdirectory.

Unit system considerations

Unit systems used by the different systems are:

Dimension \\ System Poseidon Nastran Sesam / GeniE
L (Length Unit) [m] for nodes [m] [m]
  [mm] for plate thicknesses    
M (Mass Unit) [t] [t] [t]
ML/T² Force Unit) [kN] [kN] [kN]

Yield stress is stored in [kN/m²] in Sesam / GeniE, but [N/mm²] in POSEIDON.

NASTRAN Bulk Data Format (BDF)

BDF Cards supported

Bulk Data

  **Name** **Description** **Read** **Write**
General        
  `MAT1` Material definition
  `MAT2` Shell Element Anisotropic Material Property Definition
  `GRID` Grid nodes
Elements        
  `CTRIA3` 3 node shaped shell elements
  `CQUAD4` 4 node shaped shell elements
  `CBEAM` Complex beams 1
  `CBAR` Simple beams
  `CROD` Trusses
  `CBUSH` Generalized Spring-and-Damper Connection
Element properties      
  `PSHELL` Properties for `CTRIA3`, and `CQUAD4`
  `PBEAM` Integral properties for `CBEAM`
  `PBEAML` Properties for `CBEAM` describing cross section
  `PBAR` Integral properties for `CBAR`
  `PBARL` Properties for `CBAR` describing cross section
  `PROD` Properties for `CROD`
  `PBUSH` Generalized Spring-and-Damper Property
Load        
  `LOAD` Load case combination
  `FORCE` Forces on Nodes
  `MOMENT` Moments on Nodes
  `CONM1` Concentrated Mass Element Connection, General Form
  `CMASS2` Scalar Mass Property and Connection
  `CMASS4` Scalar Mass Property and Connection to Scalar Points Only
  `GRAV` Acceleration or Gravity Load
Misc        
  `ENDDATA` Marker for end of input file
  `PARAM` Specifies values for parameters used in solution sequences or user written `DMAP` programs.

Header Data

**Name** **Description** **Read** **Write**
`SOL` Execute a Solution Sequence
`CEND` End of Executive Control Delimiter
`TITLE` Output Title
`ECHO` Bulk Data Echo Request
`DISPLACEMENT` Displacement Output Request
`SPCFORCES` Single-Point Forces of Constraint Output Request
`STRESS` Element Stress Output Request
`LOAD` External Static Load Set Selection
`SUBTITLE` Output Subtitle
`SUBCASE` Subcase Delimiter
`BEGIN` `BULK` Case Control and Bulk Data Delimiter

DNV GL Seasam Input Interface File (FEM)

FEM Cards supported

  **Name** **Description** **Read** **Write** **Page2**
General          
  `DATE` Date and Program Information 4-2
  `GCOORD` Nodal Coordinates 6-56
  `GNODE` Correspondence between External and Internal Node Numbering, and Number of Degrees of Freedom of Each Node 6-80
  `IDENT` Identification of Superelements 4-3
  `IEND` End of a Superelement 4-4
Elements          
  `GELMNT1` Element Data Definition 6-65
  `GELREF1` Reference to Element Data 6-66
Element properties        
  `GBEAMG` General Beam Element Data 6-49
  `GBARM` Cross Section Type Massive Bar 6-48
  `GIORH` Cross Section Type I or H Beam 6-71
  `GLSEC` Cross Section Type L-Section 6-76
  `GPIPE` Cross Section Type Tube 6-81
  `GUSYI` Cross Section Type Unsymmetrical I-Beam 6-93
  `GECCEN` Eccentricities 6-61
  `BELFIX` Flexible Joint/Hinge 6-8
  `GELTH` Thickness of Two-dimensional Elements 6-70
Load          
  `BLDEP` Nodes with Linear Dependence 6-27
  `BNBCD` Nodes with Boundary Conditions 6-30
  `BNDISPL` Nodes with Prescribed Displacements and Accelerations 6-31
  `BNLOAD` Nodes with Loads 6-35
  `MGSPRNG` Element to Ground 6-103
  `TDLOAD` **not documented** (Seems to be similar to `TDMATER` or `TDSETNAM`)  
  `BEUSLO` Elements with Surface Loads 6-21
Superel.          
  `BSELL` Subelement Load Description 7-27
  `GELMNT2` Subelement Description with Simple Correspondence 7-31
  `HSUPSTAT` Superelement Statistical Information 7-40
  `HSUPTRAN` Superelement Transformations 7-41
  `HIERARCH` Superelement Hierarchy Description 7-38
  `TDSUPNAM` Name and Description of a Super-Element. 4-8
Misc          
  `GSETMEMB` Set (group) of Nodes or Elements (Members) 6-84
  `GUNIVEC` Specification of Local Element Coordinate System 6-92
  `MISOSEL` Isotropy, Linear Elastic Structural Analysis 6-115
  `MORSMEL` Anisotropy, Linear Elastic Structural Analysis, 2-D Membrane Elements and 2-D Thin Shell Elements 6-117
  `TDSETNAM` Name and Description of a Set (group) 4-7
  `TEXT` User supplied Text 4-10

Element Types in SESAM

Conventions for use of the interface file for the elements in SESAM are defined here. Other element types may be introduced for use in other programs.

The table below contains element type numbers already reserved. (Not all of them are included in SESAM).

For ADVANCE, the element types listed are those available from the SESAM preprocessors. In addition to that ADVANCE has a lot of other element types.

Table 1: List of existing Element Types
**Typ3** **Name** **N.4** **Description of Element** **Ref.** **5** **6** **7** **8** **9** **Other10**
1     *Not* *yet* *defined*              
2 `BEPS` 2 2-D, 2 Node Beam 3, 5        
3 `CSTA` 3 Plane Constant Strain Triangle 2, 4      
4     *Not* *yet* *defined* 3            
5 `RPBQ` 4 Rectangular Plate. Bending Modes 3            
6 `ILST` 6 Plane Lin. Strain Triangle 2        
7     *Not* *yet* *defined*              
8 `IQQE` 8 Plane Quadrilateral Membrane Element 2        
9 `LQUA` 4 Plane Quadrilateral Membrane Element 2, 4      
10 `TESS` 2 Truss Element 2, 4  
11 `GMAS` 1 1-Noded Mass-Matrix        
12 `GLMA` 2 2-Noded Mass-Matrix            
13 `GLDA` 2 2-Noded Damping-Matrix              
14     *Not* *yet* *defined*              
15 `BEAS` 2 3-D, 2 Node Beam 2, 4 FR, LA, PL, PR, WA
16 `AXIS` 2 Axial Spring   11 FR
17 `AXDA` 2 Axial Damper      
18 `GSPR` 1 Spring to Ground 4 FR
19 `GDAM` 1 Damper to Ground      
20 `IHEX` 20 Isoparametric Hexahedron 2     FR
21 `LHEX` 8 Linear Hexahedron 2, 4     FR
22 `SECB` 3 Subparametric Curved Beam 2            
23 `BTSS` 3 General Curved Beam 2       PL, PR
24 `FQUS` 4 Flat Quadrilateral Thin Shell 4     PL, PR
24 `FFQ` 4 Free Formulation Quadrilateral Shell 5          
25 `FTRS` 3 Flat Triangular Thin Shell 4     PL
25 `FFTR` 3 Free Formulation Triangular Shell 5          
26 `SCTS` 6 Subparametric Curved Triangular Thick Shell 2       PL
27 `MCTS` 6 Subparametric Curved Triangular Thick Sandwich Element 212        
28 `SCQS` 8 Subparametric Curved Quadrilateral Thick Shell 2       PL, PR
29 `MCQS` 8 Subparam. Curved Quadr. Thick Sandwich Elem. 212        
30 `IPRI` 15 Isoparametric Triangular Prism 2      
31 `ITET` 10 Isoparametric Tetrahedron 2          
32 `TPRI` 6 Triangular Prism 2, 4      
33 `TETR` 4 Tetrahedron 2          
34 `LCTS` 6 Subparam. Layered Curved Triangular Thick Shell 212        
35 `LCQS` 8 Subparam. Layered Curved Quadrilat. Thick Shell 212        
36 `TRS1` 18 2nd Order Hexahed. Transition Elem., Solid / Shell 6         PR
37 `TRS2` 15 2nd Order Hexahed. Transition Elem., Solid / Shell 6         PR
38 `TRS3` 12 2nd Order Hexahed. Transition Elem., Solid / Shell 6         PR
39     *Not* *yet* *defined*              
40 `GLSH` 2 General Spring / Shim Element 13      
41 `AXCS` 3 Axisymmetric Constant Strain Triangle 7, 5      
42 `AXLQ` 4 Axisymmetric Quadrilateral 7, 5      
43 `AXLS` 6 Axisymmetric Linear Strain Triangle 7        
44 `AXQQ` 8 Axisymmetric Linear Strain Quadrilateral 7        
45 `PILS` 1 Pile / Soil 4        
46 `PCAB` 2 Plane Cable-Bar Element 4        
47 `PSPR` 1 Plane Spring Element 4        
48   4 4-node Contact Element with triangular Shape 4          
49   2 2-Noded Link Element 4          
50     *Not* *yet* *defined*              
51 `CTCP` 2 2-Noded Contact Element              
52 `CTCL` 4 4-Noded Contact Element              
53 `CTAL` 4 4-Noded Axisymmetric Contact Element              
54 `CTCC` 6 6-Noded Contact Element              
55 `CTAQ` 6 6-Noded (3+3) Axisymmetric Contact Element            
56 `CTLQ` 8 8-Noded (4+4) Contact Element 8, 9           PR
57 `CTCQ` 16 16-Noded (8+8) Contact Element 8, 9         PR
58 `CTMQ` 18 18-Noded (9+9) Contact Element 8, 9           PR
59     *Not* *yet* *defined*              
60     *Not* *yet* *defined*              
61 `HCQS` 9 9-Noded Shell Element           PR
62     *Not* *yet* *defined*              
63     *Not* *yet* *defined*              
64     *Not* *yet* *defined*              
65     *Not* *yet* *defined*              
66 `SLQS` 8 Semiloof Quadrilateral Curved Thin Shell (32 d.o.fs)              
67 `SLTS` 6 Semiloof Triangular Curved Thin Shell (24 d.o.fs)              
68 `SLCB` 3 Semiloof Curved Beam (11 d.o.fs)              
69     *Not* *yet* *defined*              
70 `MATR` *n* General Matrix Element with arbitrary no. of nodes (*n*)           SP
                   
100 `GHEX` 21 General Hexahedron            
                   
163 `GHEX` 27 General Hexahedron            

Footnotes

1 Twisting CBEAM cross section by using the BIT flag is not supported. Offset via OFFT is only supported for the same offset at A and B end of beam.

2 References page in "Technical Report: Sesam Input Interface File, File Description", Document id: 89-7012, Revision Number 9 / 01

3 ELTYP

4 Number of nodes

5 Indcluded in program PREFRAME

6 Included in program PREFEM

7 Included in program SESTRA

8 Included in program ADVANCE

9 Included in program Poseidon

10 FR = FRAMEWORK, LA = LAUNCH, PL = PLATEWORK, PR = PRETUBE, SP = SPLICE, WD = WADAM, WJ = WAJAC

11 Temporarily ADVANCE interprets Axisl Spring as link element, ignoring the material reference. The 6 matrix numbers are given in direct input to ADVANCE.

12 The element subroutines are the same as for the subparametric curved thick shells (SCQS and SCTS).

13 As General Spring it is just a 2-noded spring (12x12 matrix) which may be in a local coordinate system. As a shim element the preprocessor(s) will only insert stiffness in the local x- and y-direction. In the analysis program(s), shim members and general springs are treated exactly in the same manner.

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C++ IO support for various FEM exchange file formats (NASTRAN BDF, DNV Sestra FEM)

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