It is a busy week and I’m in between meetings for about 30 minutes, just enough time for a very short Focus posting for the week.  So, I thought I would share something I had to remember for the first time in a long time: How to access beta features in ANSYS Workbench.

First off a word of warning:  Beta features are beta features. They are capabilities in the software that have either not finished testing, are not fully documented, or that have a known issue.  They therefore must be used AT YOUR OWN RISK!!!!   If you find a bug or a problem, report it to your technical support provider, they need that feedback. But don’t call up indignant because it is not working the way you want it, or because the documentation is non-existent.  It is a beta feature.

Set the Option

Not too difficult.  From the Project Schematic page go to the tools menu and select Options.

Now in the Options dialog click on Appearance in the tree on the left.  You will not see Beta Options.  Scroll down and near the bottom there are a bunch of check boxes. Check “Beta Options”

Now, in your project toolbar you should see (Beta) next to the exposed beta functions:

This will also impact any beta features, if any, in the workbench native applications:  Parameter manager, Engineering Data, or DesignXplorer.

That is it. I promised short.  Off to another meeting.

Remember, USE AT YOUR OWN RISK.

Here are the files from the webinar held on Friday, April 27, 2012: A Constraint Equation Primer: How to Tie Degrees of Freedom Together

PowerPoint:

Link to webinar recording: 

https://padtincevents.webex.com/padtincevents/lsr.php?AT=pb&SP=EC&rID=5166247&rKey=a4e4b3f37223d78d

No models or anything on this one.

Don’t you hate it when you miss someone’s birthday?  I was looking up an old article in the Focus and noticed that the first issue was published on January, 13th, 2002. 

Happy Belated Birthday!

It was sometime in 2001 that Rod Scholl pointed out that there was no good ANSYS newsletter out there.  People would do one or two issues then get busy and never put out any more, or only publish once in a while.  So we decided that we would not only do a newsletter, but that we would keep it up and publish  on a regular basis. The first issue came out as an HTML email on January 13th of 2002. 

The First Issue of The Focus

And Rod was instrumental in keeping us on track and making sure that with it. Since then we published 74 actual newsletters before switching to a blog format in 2010.  Just before this one goes up on the blog, we will have published 59 The Focus articles.

Thank you to everyone who subscribes to The Focus and reads our postings, rates us, and sends us such great comments and questions.  

Here is to 10 more years!

We just finished our webinar for 4/12/2012 on the basics of the POST26 Time History Post Processor.  As promised, here are the files used for examples in the webinar, as well as the PowerPoint:

Tower-of-Test (ToT) test model, APDL:

Tower-of-Test (ToT) test model, ANSYS Mechanical with APDL Snippets:

PowerPoint Presentation:

A recording of this webinar will be available on the following site after 4/13/2012:

padtincevents.webex.com

Click on  PADT ANSYS Webinar Series to see all recordings.

So it is Friday afternoon and that big, involved, deep-dive into some arcane ANSYS capability is still not written.  So, time for plan B and the list of not so involved but still somewhat arcane capabilities that we like to expose in The Focus.  At the top of that list right now is how to change the results in an ANSYS Mechanical APDL (MAPDL) solve. 

One might ask why would you want to do this?  Well the most common usage is that you want to use APDL to calculate some result value and then display it in a plot.  Similarly, you may want to do some sort of calculation or post processing on MAPDL results but using and external piece of code, but still show the results in ANSYS.  Another common usage is to use MAPDL as a post processor for some external solver. 

And, it turns out, it is pretty easy.  And, as you probably have learned by now if you use MAPDL a lot, there is more than one way to do it.

The “Database”

Before we get into how to do this, we need to talk about the “database” in MAPDL. If you read through the documentation on the commands we will use, it will talk about the database.  This is not the jobname.db file.  That is the db file.  The database refers to the representation of your model, including results and the currently active loads, in memory when you are running MAPDL. 

When you do a RESUME command, MAPDL reads the DB file and stores the model, including geometry, mesh, loads, and run parameters, in memory.  When you do a SET command, it then adds the results and related information into memory. 

So when we use the commands we will talk about next, you are changing what is in the database, not what is in the DB file on your disk.  And you are storing it temporarily.  Many different commands cause the database to go back to its original values.  So you need to be very careful in how you use these tools, and don’t assume that once you have used them, the changes are permanent.  

DNSOL

The simplest way to do it is with the DNSOL command: DNSOL, NODE, Item, Comp, V1, V2, V3, V4, V5, V6

So, if you do a dnsol,32,u,x,3.145  the value in memory for deflection in the X direction will be changed to 3.145.  dnsol,32,s,x,1.1,2.2,3.3 will change the stress on node 32 in the X direction to 1.1, in the Y direction to 2.2, and in the Z direction to 3.3. 

The second argument can also be a component, so you can assign a uniform result value to many nodes at the same time. 

Here is an example, very simple, of a block where we set the deflection on the top nodes to 1 in.

   1: finish

   2: /clear

   3: /prep7

   4: blc4,-2,-2,4,4,20

   5: et,1,185

   6: mptemp,1,70

   7: mpdata,ex,1,1,20e6

   8: mpdata,nuxy,1,1,.23

   9: mpdata,dens,1,1,.001

  10:  

  11: vmesh,all

  12: /view,1,1,1,1

  13: /vup,1,z

  14: /RGB,INDEX,100,100,100, 0

  15: /RGB,INDEX, 80, 80, 80,13

  16: /RGB,INDEX, 60, 60, 60,14

  17: /RGB,INDEX, 0, 0, 0,15

  18: /show,png

  19: eplot

  20:  

  21: nsel,s,loc,z,0

  22: cm,nbt,node

  23: d,all,all

  24: nsel,s,loc,z,20

  25: cm,ntp,node

  26: f,all,fx,10

  27: f,all,fy,12

  28: allsel

  29: save

  30:  

  31: /solu

  32: solve

  33: finish

  34: /post1

  35: plnsol,u,sum

  36:  

  37: dnsol,ntp,u,y,1

  38: plnsol,u,sum

  39:  

  40: /show,close

The Fancy Mesh

The Normal Solution

Solution with 1” deflection DNSOL’d onto the top nodes

Pretty simple. 

NOTE: One key thing to remember is you can not use this with Powergraphics. You must have /graph,full turned on.

*VPUT

The DNSOL is great for a few nodes here and there, or a constant value. But it makes for a big nasty *do loop if you want to do a lot of nodes. So ANSYS, Inc. give us the *VPUT command:

*VPUT, ParR, Entity, ENTNUM, Item1, IT1NUM, Item2, IT2NUM, KLOOP

As you can see, this command has a lot of options, so read the Help before you use it. Most of the time you have an array that stores the value you want stuck on your model in an array (ParR).  Then you specify what MAPDL result you want to overwrite and it takes care of it for you.

*vput,nws1(1),node,1,s,1 will place new values for maximum principal stress on all the nodes covered in the array , starting at 1. 

Here is an example of the code, after the same solve as above, to do a *vput instead of a DNSOL:

   1: finish

   2: /post1

   3: plnsol,u,sum

   4:  

   5: *get,nmnd,node,,num,max

   6: *dim,nwux,,nmnd

   7: *do,i,1,nmnd

   8:     nwux(i) =  i

   9: *enddo

  10:     

  11: *vput,nwux(1),node,1,u,x

  12: plnsol,u,sum

The code places a displacement in the X direction equal to its node number.  So node 80 has a UX of 80. 

A key thing to note with *vput is that it is much more transient. Pretty much any other command that involves anything other than plotting or listing blows away the values you assigned with *VPUT.  So we recommend that you do a *vput before every plot or listing you do.

Thoughts, Questions, and Conclusion

Of course you should never use this to fudge results. 

You can get very fancy with this. When I use it I often turn off all the plot controls and then create my own legend. That way I can put hours of life on as temperature or SX and then make my own legend that says LIFE or something of the sort. 

Another thing to note is that if you DNSOL or *VPUT a displacement, then ANSYS will distort your plot by that much.  That is OK if you are changing deflection, but not so good if you are plotting life or some esoteric stress value.

A common question when you play with these commands is if you can store the modified results in the RST file.  You can for degree of freedom results, but not for stresses.  You use LCDEF and RAPPND. 

And what about ANSYS Mechanical?  Well it works totally different, and better. You can do all of this using Design Assessment, which was covered in a webinar and a Focus article you can find here.

The key to using these two commands is pretty much the same as any APDL command: Start on a small test model, write a macro to do it, and keep things simple. And, read the manual.  Everything you need to know is in there.