Learning Forum

[Huda111]

I want to perform a ,odal analysis of a metallic structure (R+3), in order to get the mass and stiffness matrices, do I need to define the type of contact or connection between the mettalic beams or not ? also how can I export those matrice in a separate file ?

Thank you.

[peteroznewman]

Please explain the shape of the metallic structure. I don't know what R+3 means. Please insert an image into your reply.
Regards Peter

[Huda111]

This is the structure I'm talking about.
Thank you for your help.

[peteroznewman]

Thank you for the image.
You show beam elements meshed on line bodies.
You have correctly drawn each line around the unit cube. Note for others reading this, a common mistake is to draw one long vertical line.
A simple way for you to connect these elements at the intersection points is to use Node Merge. Right click on the Mesh and Insert a Node Merge Group. Type in a Tolerance value then right click on the folder and select Detect Connections, the folder will fill with connections. Then right click and Generate, that will replace multiple coincident nodes with a single node.
If the lines were drawn in SpaceClaim, you would create Shared Topology by going to the Workbench tab and clicking on the Share button, which would create a shared node at each intersection, then you would not need to use Node Merge.
Shared Topology can also be created in DesignModeler.
Several discussions have appeared on this site on how to export the mass and stiffness matrix out of ANSYS for use in matlab or other programs.
Please see documentation on SEOPT. Open ANSYS Help, then copy/paste the URL below into the Help address bar.
https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v212/en/ans_cmd/Hlp_C_SEOPT.html?q=seopt
You can insert code into Mechanical using a Command Object. The following should get you both stiffness and mass.
seopt, file, 2, 1
Here is a video from ANSYS from 2018.

[Huda111]

Thank u so much.
well I tried the code from the video but it didn't work out for me, I guess I have a problem with the installation, I'll try to do everything all over again.
Grateful.

[Huda111]

hello again well I finally got the stiffness matrix and still struggling with the mass matrix, yet the problem i face is related to the dimension of them, the program consider all 6 DOFs per node, and I'm interested only in the first 3, any idea how can I fix that ?
Thank u.

[peteroznewman]

I don't know what you intend to do with the stiffness matrix so I can't say what you should do.