Beam 3-point bending (Connector Nastran)

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Input and output files

The original input and output files can be found with the examples of COSSAN, in the folder containing the files related to finite element model.

A screenshot of the model:

Beam nas.png

Additional inputs

For the analysis using Nastran, functions dedicated to the inertia moment and area of the beam have to be created.

The function dedicated to the inertia moment of the beam with respect to the direction perpendicular to the beam is named Inertia22, its expression is:


Please find here a link to Parameter (editor).


A new connector is created. The following figure shows the wizard for creation of Connector.

Definition of the connector to Abaqus

The 3rd party solver is selected among the different configurations available, which have been initially predefined. Please select Nastran in the configuration drop-down box.

Click then on Finish. The following window appears:

Original aspect of the connector page

The following actions need to be performed:

Import Input/output files in the project

All the input files requires to run a 3rd party software should be imported into the COSSAN-X project. All the files are handled in the section File management, which displays the currently available files. The files can be imported one by one by clicking on Import file, or the content of a directory can be imported by clicking on Import directory.

In this example, the ASCII input file named beam.bdf is necessary for running the simulation.

Bulbgraph.png Output files of the 3r party software
The output files generated by the solver must to be imported in order to define an extractor

Define Input files

All the input files (and the files necessary to successful run the 3rd party software) are specified in the Input box.

Selecting the appropriate input format, the keywords and structure of the ascii input files are automatically detected.

The main input file is used in the definition of the connector. Its name will be automatically used by the connector while calling the solver (see Connector (editor)).

The input files consists of all file that will be copied to the execution folder. The files that require to be modified by COSSAN-X are selected by activating the check-box left to the file name. The extension .cossan is automatically and temporary added to this files. These files are used to define new Injectors, in order to inject values from COSSAN-X (realizations of the Random variables,...).

More informations about the connectors can be found on the user manual page of the object: Connector (editor), Connector (wizard)

Define output files

All the output files used to recover quantities of interest are specified in the Output category.

The output file will be used to define extractors, retrieving results from the simulations.

In the case of this example, the connector editor look as following after all the input and output files have been specified. The names of the files might have to be changed in order to match the definition of the connector and the version of the finite element software.

Aspect of the connector page


Identifiers are set in order to inject the quantities of interest at the right position in the input file. In this example, identifiers are defined for the cross section, the inertia moment of the beam, the material properties and the point force.

Definition of the injector
Definition of the injector (continued)
Definition of the injector (continued)

The name of each identifier is identical to the name of the object to inject to inject. The format is that of Nastran.


The extractor is used to retrieve the quantity of interest. In this example this is the vertical displacement at the mid-point of the beam, that is to say the displacement of node 21 in the y-direction

First an anchor is defined at the header of the table of the nodal displacements. Then an identifier is set at the position of the quantity of interest in the output file. The response properties have to be set: only one value is extracted, it will be given the name u_y.

Properties of the response

The response has to be linked to the anchor by dragging it.

Response and anchor in the extractor

See also