Product: ABAQUS/Standard
The abaqus tozaero interface enables you to exchange aeroelastic data between the ABAQUS and ZAERO analysis products. By using this interface between the applications, you can perform structural modal analysis on a model in ABAQUS, transfer the model to ZAERO for aeroelastic analysis, then transfer it back to ABAQUS for stress analysis.
The universal file is the means of data exchange between ABAQUS and ZAERO. It consists of four data sets: 2411, which describes node and coordinate data; 2414, which describes mass-normalized mode shapes; 2420, which describes the global coordinate system; and 2453, which describes the mass matrix in text format, or 2453b, which describes the mass matrix in binary format.
You can specify the universal file's output format by using the mode parameter. Choosing text format enables you to modify the universal file in a text editor but increases the file size to over twice that of similar files in binary format. Text is the default format and the only format supported by ZAERO. Table 3.2.23–1 and Table 3.2.23–2 describe the mass matrix data set text format and binary format, respectively.
Table 3.2.23–1 Format for data set 2453 (text).
| Record | Field | Description | Format |
|---|---|---|---|
| 1 | 1 | Matrix Identifier 1: DOF 131: Mass 139: Stiffness 147: Back-expansion | (I10) |
| 2 | 1 | Matrix Data Type 1: Integer 2: Real 4: Double Precision 5: Complex 6: Complex Double Precision | (6I10) |
| 2 | Matrix Form 3: General Rectangular | ||
| 3 | Number of rows | ||
| 4 | Number of columns | ||
| 5 | Storage Key 1: Row 2: Column 11: Sparse (not supported for IMAT=1) | ||
| 6 | Matrix Size Parameter For IMAT=1 this is the number of dynamic modes. For sparse this is the number of matrix entries. Otherwise, 0. | ||
| 3 for storage keys 1 and 2 | N/A | Matrix Data | For data type 1: (8 I10) For data type 2: (4 E20.12) For data type 4: (4 D20.12) For data type 5: (2 (2 E20.12)) For data type 6: (2 (2 D20.12)) |
| 3 for storage key 11 | 1 | Row | For data type 1: (2 (2I10 1I10)) For data type 2: (2 (2I10 1E20.12)) For data type4: (2 (2I10 1D20.12)) For data type 5: (1 (2I10 2E20.12)) For data type 6: (1 (2I10 2D20.12)) |
| 2 | Column | ||
| 3 | Value at cell |
Table 3.2.23–2 Format for data set 2453b (binary).
| Record | Field | Description | Format |
|---|---|---|---|
| Header | 1 | 2453 | (I6) |
| 2 | Lowercase b | (IA1) | |
| 3 | Byte Ordering Method 1: Little Endian (Windows and DOS) 2: Big Endian (most UNIX) | (I6) | |
| 4 | Floating Point Format 1: DEC VMS 2: IEEE 754 (UNIX) 3: IBM 5/370 | (I6) | |
| 5 | Number of ASCII lines following 2 for data set 2453b | (I12) | |
| 6 | Number of bytes following ASCII lines | (I12) | |
| 7–10 | Not used (fill with zeros) | ||
| 1 | 1 | Matrix Identifier 1: DOF 131: Mass 139: Stiffness 147: Back-expansion | (I10) |
| 2 | 1 | Matrix Data Type 1: Integer 2: Real 4: Double Precision 5: Complex 6: Complex Double Precision | (6I10) |
| 2 | Matrix Form 3: General Rectangular | ||
| 3 | Number of rows | ||
| 4 | Number of columns | ||
| 5 | Storage Key 1: Row 2: Column 11: Sparse (not supported for IMAT=1) | ||
| 6 | Matrix Size Parameter For IMAT=1 this is the number of dynamic modes. For sparse this is the number of matrix entries. Otherwise, 0. | ||
| 3 (Binary Matrix Data) | 1 (4 bytes) | Row | For data type 1: (2 Int32 1 Int32) For data type 2: (2 Int32 1 Flt32) For data type 4: (2 Int32 1 Dbl64) For data type 5: (2 Int32 2 Flt32) For data type 6: (2 Int32 2 Dbl64) |
| 2 (4 bytes) | Column | ||
| 3 | Value at cell |
Before the interface can create the universal file, you must make the following additions to your ABAQUS input (.inp) file, then run ABAQUS:
Normalize the eigenvectors in the eigenfrequency extraction analysis with respect to the structure’s mass matrix. This normalization is necessary because the translator assumes the mode shapes are mass normalized; if you skip this step before the ABAQUS run, the modes translated will be incorrect and will give incorrect results with no warnings or errors. For more information, see “Natural frequency extraction,” Section 6.3.5.
Include the following line in the analysis step:
*ELEMENT MATRIX OUTPUT, ELSET=allelements, MASS=YES, OUTPUT FILE=USER DEFINED, FILE NAME=mtx-file-namewhere allelements is a defined element set containing all the elements that should be included in the global mass matrix. The matrix output will be placed into the file mtx-file-name.mtx; you should not specify the .mtx extension since ABAQUS adds it automatically.
This section describes the input and output of the three main steps in the workflow between ABAQUS and ZAERO.
The ABAQUS modal analysis uses an ABAQUS input file and outputs the following data to an output database (.odb) file and matrix (.mtx) file: structural model nodes, coordinate systems, mode frequencies, generalized mass, mode shapes, and the mass matrix.
This option is used to specify the name of the ABAQUS input file. It is also the default name for the universal output database and mass matrix files.
This option is used to specify the name of the universal file if it is different from job-name. If the .unv extension is not supplied, ABAQUS adds it automatically.
This option is used to specify the name of the ABAQUS output database file if it is different from job-name. If the .odb extension is not supplied, ABAQUS adds it automatically.
This option is used to specify the file containing the element mass matrices generated by ABAQUS. If the .mtx extension is not supplied, ABAQUS adds it automatically.
This option specifies the step number containing the eigenfrequency extraction results from ABAQUS. The default value is 1.
Note: You must normalize the eigenvectors in the eigenfrequency extraction analysis with respect to the structure’s mass matrix. For more information, see “Natural frequency extraction,” Section 6.3.5.
This option specifies the output format of the universal file. If this option is set equal to binary, ABAQUS writes a portion of the universal file in binary format to save space. If this option is set equal to text, ABAQUS writes the entire file in all text format. The default value is text, which is the only mode currently supported by ZAERO.