XANSYS Forum Index
    Register    

FAQ    Search    Memberlist    Usergroups    SmartFeedSmartFeed    Profile    Log in
Second derivative of temperature over time
 
This forum is locked: you cannot post, reply to, or edit topics.   This topic is locked: you cannot edit posts or make replies.    XANSYS Forum Index -> XANSYS
Author Message
david.unobe
User


Joined: 03 Dec 2012
Posts: 24

PostPosted: Thu Jul 31, 2014 9:45 pm  Reply with quote

Good day,
I am currently working on a structural-thermal coupled analysis of a steel plate. After carrying out a transient solution for applied temperature, I would like to determine the second derivative of the nodal temperature results over time in the ANSYS time history post processor.
If this is possible please how do I go about it?

Thanks for your help.
_________________
David Unobe
Research Assistant,
Idaho State University
Back to top
View user's profile Send private message
jose.galan
User


Joined: 21 Oct 2008
Posts: 140

PostPosted: Fri Aug 01, 2014 12:09 am  Reply with quote

Dear Mr. Unobe,

you can store the nodal temperature in a variable with the command nsol

!obtain node at a certain position

indnode=node(10.0,3.2,1,1)

!store nodal temperature in variable 2

! Warning: never use variable 1, because it stores time

nsol,2,indnode,temp

!Calculate first derivative of variable 2 (nodal temperature) with
respect to variable 1 (time) and store it on variable 3

deriv,3,2,1

!Calculate first derivative of variable 3 (dT/dt) with respect to
variable 1 (time) and store it on variable 4

deriv,4,3,1

!plot d^22T/dt^2 against time

plvar,4

Best regards,

Jose M. Galan

Constr. Eng. Dept.

Univ. Sevilla

Spain

El 01/08/2014 06:45, david.unobe escribió:

Quote:
Good day,
I am currently working on a structural-thermal coupled analysis of a steel plate. After carrying out a transient solution for applied temperature, I would like to determine the second derivative of the nodal temperature results over time in the ANSYS time history post processor.
If this is possible please how do I go about it?

Thanks for your help.

------------------------
David Unobe
Research Assistant,
Idaho State University

+-------------------------------------------------------------+
| XANSYS web - www.xansys.org/forum |
| The Online Community for users of ANSYS, Inc. Software |
| Hosted by PADT - www.padtinc.com |
| Send administrative requests to xansys-mod@tynecomp.co.uk |
+-------------------------------------------------------------+

Post generated using Mail2Forum (http://www.mail2forum.com)
Back to top
View user's profile Send private message
mike.yaksh
User


Joined: 05 Feb 2009
Posts: 291

PostPosted: Fri Aug 01, 2014 6:12 am  Reply with quote

David
As pointed out, you can use /post26 for a node by node calculation. Is this what you want, or do you want to contour the derivative at each node at a particular time?
Mike Yaksh
NAC International

-----Original Message-----
From: Xansys [mailto:xansys-bounces@xansys.org] On Behalf Of david.unobe
Sent: Friday, August 01, 2014 12:45 AM
To: xansys@xansys.org
Subject: [Xansys] Second derivative of temperature over time

Good day,
I am currently working on a structural-thermal coupled analysis of a steel plate. After carrying out a transient solution for applied temperature, I would like to determine the second derivative of the nodal temperature results over time in the ANSYS time history post processor.
If this is possible please how do I go about it?

Thanks for your help.

------------------------
David Unobe
Research Assistant,
Idaho State University






+-------------------------------------------------------------+
| XANSYS web - www.xansys.org/forum |
| The Online Community for users of ANSYS, Inc. Software |
| Hosted by PADT - www.padtinc.com |
| Send administrative requests to xansys-mod@tynecomp.co.uk |
+-------------------------------------------------------------+
+-------------------------------------------------------------+
| XANSYS web - www.xansys.org/forum |
| The Online Community for users of ANSYS, Inc. Software |
| Hosted by PADT - www.padtinc.com |
| Send administrative requests to xansys-mod@tynecomp.co.uk |
+-------------------------------------------------------------+

Post generated using Mail2Forum (http://www.mail2forum.com)
Back to top
View user's profile Send private message
david.unobe
User


Joined: 03 Dec 2012
Posts: 24

PostPosted: Fri Aug 01, 2014 10:06 am  Reply with quote

Good day,
Thanks for the advice. I tried to carry out a node by node derivative but I keep getting an error that the derivative command requires four data points. However, i can only select one node to work with at a time.
Please do you have any ideas why this is?

Thanks for all the help
_________________
David Unobe
Research Assistant,
Idaho State University
Back to top
View user's profile Send private message
keith.technologies
User


Joined: 05 Feb 2009
Posts: 100

PostPosted: Fri Aug 01, 2014 10:33 am  Reply with quote

It sounds as though your results file may contain the results of only
the last time step during your transient analysis. To force the
writing of all of your transient solutions to the results file you
should issue an OUTRES,ALL,ALL before your solve.

Keith DiRienz
FEA Technologies

At 10:06 AM 8/1/2014, you wrote:
Quote:
Good day,
Thanks for the advice. I tried to carry out a node by node
derivative but I keep getting an error that the derivative command
requires four data points. However, i can only select one node to
work with at a time.
Please do you have any ideas why this is?

Thanks for all the help

------------------------
David Unobe
Research Assistant,
Idaho State University






+-------------------------------------------------------------+
| XANSYS web - www.xansys.org/forum |
| The Online Community for users of ANSYS, Inc. Software |
| Hosted by PADT - www.padtinc.com |
| Send administrative requests to xansys-mod@tynecomp.co.uk |
+-------------------------------------------------------------+

Keith DiRienz
Office: 949.481.4946
FEA Technologies
+-------------------------------------------------------------+
| XANSYS web - www.xansys.org/forum |
| The Online Community for users of ANSYS, Inc. Software |
| Hosted by PADT - www.padtinc.com |
| Send administrative requests to xansys-mod@tynecomp.co.uk |
+-------------------------------------------------------------+

Post generated using Mail2Forum (http://www.mail2forum.com)
Back to top
View user's profile Send private message
david.unobe
User


Joined: 03 Dec 2012
Posts: 24

PostPosted: Sun Aug 03, 2014 10:27 am  Reply with quote

Thanks sir, that was very helpful. I have been able to get the derivative of the node now. Also, I have another question. I am wondering if it will be possible to perhaps do this for all the nodes in the results file at once or will I have to do it node by node?

Thanks for all your help.

keith.technologies wrote:
It sounds as though your results file may contain the results of only
the last time step during your transient analysis. To force the
writing of all of your transient solutions to the results file you
should issue an OUTRES,ALL,ALL before your solve.

Keith DiRienz
FEA Technologies

_________________
David Unobe
Research Assistant,
Idaho State University
Back to top
View user's profile Send private message
mike.yaksh
User


Joined: 05 Feb 2009
Posts: 291

PostPosted: Mon Aug 04, 2014 5:50 am  Reply with quote

David

Yes. Some APDL would obtain the results you need using *VGET, *VMASK, *VOPER. You would set up a loop using *do, *enddo to load (*VGET) the data for all the active nodes into some TABLE s, and use the *VOPER to get the derivative. The main problem is that you are not doing a curve fit, but computing the derivative using the data loaded from each time step. This might require more result sets. If you are satisfied with the Time History approach for each node, it should be satisfactory for this approach also. DO you want to contour this, or just print it out?
Mike Yaksh
NAC International
Norcross GA

-----Original Message-----
From: Xansys [mailto:xansys-bounces@xansys.org] On Behalf Of david.unobe
Sent: Sunday, August 03, 2014 1:27 PM
To: xansys@xansys.org
Subject: Re: [Xansys] Second derivative of temperature over time

Thanks sir, that was very helpful. I have been able to get the derivative of the node now. Also, I have another question. I am wondering if it will be possible to perhaps do this for all the nodes in the results file at once or will I have to do it node by node?

Thanks for all your help.


keith.technologies wrote:
Quote:
It sounds as though your results file may contain the results of only
the last time step during your transient analysis. To force the
writing of all of your transient solutions to the results file you
should issue an OUTRES,ALL,ALL before your solve.

Keith DiRienz
FEA Technologies


------------------------
David Unobe
Research Assistant,
Idaho State University






+-------------------------------------------------------------+
| XANSYS web - www.xansys.org/forum |
| The Online Community for users of ANSYS, Inc. Software |
| Hosted by PADT - www.padtinc.com |
| Send administrative requests to xansys-mod@tynecomp.co.uk |
+-------------------------------------------------------------+
+-------------------------------------------------------------+
| XANSYS web - www.xansys.org/forum |
| The Online Community for users of ANSYS, Inc. Software |
| Hosted by PADT - www.padtinc.com |
| Send administrative requests to xansys-mod@tynecomp.co.uk |
+-------------------------------------------------------------+

Post generated using Mail2Forum (http://www.mail2forum.com)
Back to top
View user's profile Send private message
david.unobe
User


Joined: 03 Dec 2012
Posts: 24

PostPosted: Mon Aug 04, 2014 9:01 am  Reply with quote

Thanks sir. I would just like to print out the nodal temperatures for the second derivative. I do not need to contour the results.

Thanks for all your help.
mike.yaksh wrote:
David

Yes. Some APDL would obtain the results you need using *VGET, *VMASK, *VOPER. You would set up a loop using *do, *enddo to load (*VGET) the data for all the active nodes into some TABLE s, and use the *VOPER to get the derivative. The main problem is that you are not doing a curve fit, but computing the derivative using the data loaded from each time step. This might require more result sets. If you are satisfied with the Time History approach for each node, it should be satisfactory for this approach also. DO you want to contour this, or just print it out?
Mike Yaksh
NAC International
Norcross GA


_________________
David Unobe
Research Assistant,
Idaho State University
Back to top
View user's profile Send private message
Display posts from previous:   
This forum is locked: you cannot post, reply to, or edit topics.   This topic is locked: you cannot edit posts or make replies.    XANSYS Forum Index -> XANSYS
All times are GMT - 7 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You cannot download files in this forum


Powered by phpBB © 2001, 2005 phpBB Group

sleek template created by Andrew Charron