Precise Mass Summary

Precise Mass Summary Output

One of the many checks one can do in FEA is to compute the mass, inertia and center of gravity. Besides doing this for the normal models, it can quickly extract out the mass and inertia of the superelement (SE) to verify the MATRIX50 that you're bringing in has the same mass and inertia as the genuine article.

If the mass comes in too low, try specifying more modes in CMSOPT to see if it fixes it. My previous co-worker also came across intermittent issues with using constraints equation (CE) inside a superelement. He replaced it with really stiff beams instead before generating the superelement.

Personally, I would take a bit of time to select master nodes (M) not just at the connections but at various points on the model to properly capture the modal mass. This would be similar to identifying accelerometer locations on your part to properly identify modes of interest for a modal test.

Here's the command to calculate it all :
ALLS $ /SOLU $ IRLF,-1 $ PSOLVE,ELFORM $ PSOLVE,ELPREP $ IRLIST

Comments

ANSYS User Defined Results

There is an abundant of options in ANSYS classic when one wishes to post process results. ANSYS workbench default pull down menu post processing options are more limited but they can still be accessed via the User Defined Results. One way not commonly used but can come in handy is as follows: Zeroth: Under Analysis Settings, there is "Output Controls" where you can toggle to "Yes" what you would like to save before the solution starts. This is like OUTRES in APDL. Output Controls First: After solving the model, click on Solution in the tree to highlight it. Solution Second: Click on Worksheet in the toolbar. Worksheet Third: In the worksheet, you will see list of results that are saved. Right click on it to create the User Defined Results. Create User Defined Results So here we have it. You could of look up the different expressions in the help document but I find this method of accessing the results convenient. Example: Aspec...

Export Stiffness Matrix from Ansys

It is sometimes useful to extract the mass and stiffness matrix from Ansys. *SMAT, MatK, D, IMPORT, FULL, file.full, STIFF *PRINT, matk, matk, txt Exporting mass matrix would be similar: *SMAT, MatM, D, import, full, file.full, MASS The above script uses APDL Math to get the job done. (Please see previous post for another example). The ordering of the matrix is unfortunately not concurrently exported. To verify the sequencing is as expected, we will work to replicate a truss example in the Finite Element Trusses course notes by Bob Greenlee. Figure 1: Truss Problem Setup Model Creation Script to create model: /prep7 !! Creates Model to reflect course notes ! Properties et ,1,1 mp , ex, 1, 29.5e6 r , 1, 1 ! Geometry n ,1 $ n ,2, 40 $ n ,3, 40, 30 $ n ,4, 0, 30 e ,1,2 $ e ,2,3 $ e ,1,3 $ e ,3,4 ! Boundary Conditions d ,1,ux,0 $ d ,1,uy,0 d ,2,uy...

ANSYS APDL Syntax Highlighting editor

Notepad++ with APDL User Defined Language The editor of my choice is Notepad++ with the available User Defined Language Files for APDL. You can install it without administrative privileges via the zip file. The best part of it is, it's FREE! After installing Notepad++, go to "Language>Define Your Language..." then "Import" the XML file downloaded from the above link. Remember to restart Notepad++ so that the language changes will take into effect. Opening up any *.inp or *.ans files should automatically switch highlighting to APDL. I made some minor edits. Here's my XML file: LINK . I also heard Sublime Text and Ultraedit has more advance features but they aren't (totally) free.

Ansys Tips

Search This Blog