利用Hypermesh和nastran创建mnf流程

利用Hypermesh和nastran创建mnf流程

1. 建立几何模型，定义材料属性、单元属性。

2. 创建约束和特征值卡，如下：

约束为无量纲。定义为mis1,选择下列四点确定一个节点集定义。 定义单元集。

特征值为EIGRL特征。

3. 对控制卡进行设置

（1） sol

（2）PARAM

(3) case_unsupported_cards

ADAMSMNF FLEXBODY=YES,OUTGSTRN=YES,OUTGSTRS=NO RESVEC=NO

GPSTRAIN(PLOT)=ALL OUTPUT(POST)

SURFACE 101 SET 100 NORMAL X3 FIBRE=Z1 (4) bulk _unsupported _cards

DTI,UNITS,1,KG,N,M,S (5) global_case_control

点选EIGRL卡

Gpstress=all

相关文档;

Output 栏中 Translating MSC.Nastran Data

There are two different interfaces that you use to translate MSC.Nastran data for use in ADAMS/Flex. Learn about:

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Using MSC.Nastran 2004 and Above Verifying the Model

Computing Stress/Strain Modes

XRB Support for Stress/Strain Modes Shortened Stress/Strain Modes

Using MSC.Nastran 2004 and Above

Starting in version 2004, MSC.Nastran provides an improved interface for generating modal neutral files (MNFs) . The new MSC.Nastran ADAMS Interface allows you to generate an MNF directly from

MSC.Nastran without generating an OUTPUT2 file. The MSC.Nastran ADAMS Interface does not require a DMAP alter or a translator to convert MSC.Nastran output files to MNFs.

The MSC.Nastran ADAMS Interface is a licensed feature of MSC.Nastran. For more information, contact your local sales representative. If you already have the MSC.Nastran ADAMS

Interface license, refer to the MSC.Nastran Quick Reference Guide and Reference Manual for information on how to use it.

Verifying the Model

The MSC.Nastran translator writes a summary of the modal neutral file (MNF) export to the terminal window. If you are using

MSC.Nastran 2004 or above, the ADAMS interface writes a summary of the MNF export to the MSC.Nastran output file. Please review this data for any concerns. In particular, ensure that the:

Mass, center of mass location, and moments of inertia are as expected.

? During the MNF write, the constraint modes and the constrained normal modes are orthogonalized. This yields modes that are:

o An approximation of the free-body normal modes.

o Interface modes, where the interface is the collection of

all the attachment point DOFs.

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Also, verify that the free body normal modes have a reasonable natural frequency. You should expect to see six rigid-body modes, unless displacement boundary conditions are present.

Computing MSC.Nastran Stress/Strain Modes

For ADAMS/Durability to process stresses or strains on flexible bodies, modal stress or strain shapes need to be present in the modal neutral file (MNF) of the flexible body. You do this by having MSC.Nastran recover a stress or strain mode for every mode shape computed for Component Mode Synthesis (CMS).

MSC.Nastran Grid Point Stresses ? Example

? Known Limitations, Problems, and Restrictions

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MSC.Nastran Grid Point Stresses

Because modal information contained in the MNF can only be associated with nodes, the MSC.Nastran grid-point stress data

recovery option is required. The following Case Control commands are required in the MSC.Nastran input file to compute stress or strain modes for the MNF:

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GPSTRESS: Requests grid point stresses output. GPSTRAIN: Requests grid point strains output. STRESS(PLOT): Requests element stress output.

STRAIN(FIBER,PLOT): Requests element strain output. OUTPUT(POST): Delimiter.

SET: Defines a set of elements for a surface or volume.

SURFACE: Defines a surface of plate elements referenced by the SET command.

VOLUME: Defines a volume of solid elements referenced by the SET command.

For more information on these commands, see the Case Control section of the MSC.visualNastran Quick Reference Guide. For more information on computing grid point stresses, see the MSC.Nastran Linear Static Analysis User's Guide.

Notes: You can only transfer one surface stress or strain fiber of plate elements to the MNF for processing in MSC.ADAMS. If more than one fiber is specified on the SURFACE card, the msc2mnf translator issues a warning message and only transfers the first surface stress fiber it finds in the OUTPUT2 file.

Including stress or strain modes in the MNF can significantly increase the file size. Therefore, it becomes even more important to optimize the MNF if possible. For information on optimizing the MNF, see Optimizing an MNF. Including both stress and strain modes will further increase the size of the MNF and is generally not

recommended for large models, unless both quantities are needed. When defining subcases in Case Control, you must have the

GPSTRESS, GPSTRAIN, STRESS, and STRAIN cards before the first SUBCASE card. In addition, the OUTPUT, SURFACE, and VOLUME cards should follow all subcase definitions and appear at the end of

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