Creating a Written Beam Structure

  • Last Post 09 July 2018
  • Topic Is Solved
learn13 posted this 12 May 2018

Say I wanted to create a cube out of beam or truss elms (2 nodes each) in static structural.  Rather than using the GUI, the coordinates of the cube's nodes and all the associated upstream and downstream components are written manually without having previously defined a geometry.

Is this process feasible in Ansys?  If so, is it still possible without having created a geometry beforehand?  

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peteroznewman posted this 14 May 2018

You can write an input text file such as the one attached, without using any GUI or having any underlying geometry.

You can submit that text file to the solver to generate output data. The solver can output data to a text file or to a database viewed in a GUI.

Here is a discussion on how to submit an input.dat file to the solver.

learn13 posted this 15 May 2018

v17.1.  Thank you for your help so far.  I'm more familiar with Workbench than Classic.  The generated .db was written as an FE/IGES .cdb in Classic, imported into External Model, and plugged into Static Structural's Model.  

A part of the project will be generating a tensegrity structure out of trusses, manually creating the nodal coordinates and truss connections is the easiest method so far.  This is based on created tensegrity structures within another program I won't mention because that's frowned upon.  The coordinates of each nodal position is known, but manually creating the nodal positions in a Ansys .dat or .cbd is proving very difficult.

Without meaning to make this a lengthy post (too late).  The imported geometry/mesh from the other program is successful.  However in Ansys, connecting trusses don't share a node as in the other program.  Instead, each truss has an independent node with the same coordinate (i.e. 2 nodes for identical coordinate).  These points cannot be connected in Model using connections.

I can see 2 options.  Make the structure in Ansys or somehow fix the imported geometry. Do you have suggestions for this task?  I can attach example files if needed.

peteroznewman posted this 15 May 2018

One of my discussions had nothing to do with ANSYS but instead was all about creating input data for ANSYS in other programs such as Excel or matlab, so don't be shy about mentioning other programs here!

Mechanical has a Node Merge capability in Release 19 and some prior releases, so you can take truss elements with independent nodes and merge the coincident nodes to connect the truss elements.  I'm not sure if it is in Release 17.1, but I can check on that.  Even if Node Merge is not in 17.1, an APDL script could be written to do that for you (but I am not an APDL code writer either).

I am also a WB user and know practically nothing about Classic. Please attach a zip file with some examples so I can see what you are trying to do, and you can sneak in a mention of the "other program" while you are replying.

learn13 posted this 15 May 2018

learn13 posted this 15 May 2018

I'm not sure my previous post went through.

If the Node Merge you are referring to is in Model instead of Geometry, I had not thought to try that.  A very promising solution, something for tomorrow.  I believe Node Merge is a part of v17.1, Node Move is available. I'll update if there are issues.

Attached is a manually written .inp file from Abaqus (^hint) and a Ansys interpretation (.dat) from the imported geometry/mesh.  Understanding the .inp should be straightforward with minimal knowledge of coding.  Beams (trusses later) are each 1 element in both programs for simplicity in these trial stages.

Possibly deserving of its own thread (if allowed), if there is a template/coding method in Ansys comparable to the attached .inp I would very much like to read about that.  I haven't found one yet, but it's probably somewhere.

learn13 posted this 15 May 2018

It would probably help to know that the current structure is a tensegrity icosohedron.  More complex structures have been made.  It's not hard to imagine why a manual method is easier in both generating, checking, and keeping track of everything.

My .inp and .dat file extension attachments aren't being allowed.  Putting them in word didn't work either. 

A photo of the Abaqus .inp is attached.  I'll work out the .dat tomorrow.

Attached Files

peteroznewman posted this 15 May 2018

This site allows zip files to be attached, which can archive any number of files of any extension. There is a 120 MB file size limit.

This site also allows .wpbz files, which is a standard for ANSYS.  I used to write ABAQUS inp files many years ago. I will check back tomorrow. 

learn13 posted this 19 May 2018

I believe I found a good, even if temporary solution.  Within the Classic GUI there is an option to define nodes by their coordinates and connect them in a specific order.  Nodal positions can also be changed by redefining the coordinates. 

@peteroznewman thank you for your help along the way!

Bode1 posted this 09 July 2018

The imported geometry/mesh from the other program is successful. However in Ansys, connecting trusses don't share a node as in the other program

peteroznewman posted this 09 July 2018

Hey Bode1,

I recommend you start a New Discussion and explain the problem you want solved in more detail. This discussion is marked as Solved which may limit who will look at it.