XANSYS Forum Index
    Register    

FAQ    Search    Memberlist    Usergroups    SmartFeedSmartFeed    Profile    Log in
[Xansys] [EMAG]Unconverging solution
 
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
mike.yaksh
User


Joined: 05 Feb 2009
Posts: 291

PostPosted: Wed Apr 29, 2009 11:01 am  Reply with quote

Hi Gabriella,

To get the current to flow, you need to constrain the VOLT at the
opposite end of the conductor and as others indicated there could be
other errors in the input to cause the "No constraint..." message. In
the post processing you can use JS (ETABLE) to see the current density.

Mike Yaksh
NAC International
Norcross GA

-----Original Message----- Gabriella Rolando [--email address suppressed--]

I want to study the temperature evolution inside a superconducting cable
in case of quench.
I have constructed a 2D model of the cable cross section which is
composed by the conductor and the surrouding insulation.
For the conductor I am using the element PLANE67, while for the
insulation the element PLANE55.
In the conductor I have a current of 200 A: in order to get a uniform
current distribution I have coupled the DOF VOLT of all the nodes of the
conductor and then applied AMPS 200 on one node.
The conductor is initially at 10 K, while the insulation at 5K.
I assume the system to be adiabatic so I don't put convection on the
outer border of the model.
I am performing a static anlysis.

My problem is that the simulation is not converging and I cannot
understand why.
In the error file I have the following warnings which I cannot
understand:

No constraints have been defined using the D command.

Material property KXX of material 2 of element 1385 is evaluated at a

temperature of 0, which is below the supplied temperature range.

Temperature range checking terminates.

Coefficient ratio exceeds 1.0e8 - Check results.

There are 1 small equation solver pivot terms. May be a transitional

effect caused by the Newton-Raphson logic.

I guess they are not all critical for the simulation to work but I
cannot understand which one is causing the problem.
Could anybody suggest me where the problem is and how to solve it?

Post generated using Mail2Forum (http://www.mail2forum.com)
Back to top
View user's profile Send private message
gabriella.rolando2
User


Joined: 21 Oct 2008
Posts: 90

PostPosted: Thu Apr 30, 2009 12:13 am  Reply with quote

Hi,

I think the problem is that I was not applying constraints on voltage at
all but I was simply applying a current on the conductor nodes. However
from what I have understood the element PLANE67 requires the definition
of constraints on voltage. As I want my current to flow perpendicular to
the plane of the model I think I should apply electric
boundary->voltage->J-normal-> on areas (DA command) on the area where
the current flows. Is it correct?

Reading the guide I have seen that 'If both a force and a constrained
degree of freedom [D] are specified at the same node, the constraint
takes precedence.'
Could anybody explain me what it means exactely? That simply the degree
of freedom is considered before the force? Or that the force is in this
case not considered at all?

Than you again

Gabriella Rolando
Technical Student @ CERN

-----Original Message-----
From: --email address suppressed-- [mailto:--email address suppressed--] On
Behalf Of Yaksh, Mike
Sent: Wednesday, April 29, 2009 8:02 PM
To: ANSYS User Discussion List
Subject: Re: [Xansys] [EMAG]Unconverging solution

Hi Gabriella,

To get the current to flow, you need to constrain the VOLT at the
opposite end of the conductor and as others indicated there could be
other errors in the input to cause the "No constraint..." message. In
the post processing you can use JS (ETABLE) to see the current density.

Mike Yaksh
NAC International
Norcross GA

-----Original Message----- Gabriella Rolando [--email address suppressed--]

I want to study the temperature evolution inside a superconducting cable
in case of quench.
I have constructed a 2D model of the cable cross section which is
composed by the conductor and the surrouding insulation.
For the conductor I am using the element PLANE67, while for the
insulation the element PLANE55.
In the conductor I have a current of 200 A: in order to get a uniform
current distribution I have coupled the DOF VOLT of all the nodes of the
conductor and then applied AMPS 200 on one node.
The conductor is initially at 10 K, while the insulation at 5K.
I assume the system to be adiabatic so I don't put convection on the
outer border of the model.
I am performing a static anlysis.

My problem is that the simulation is not converging and I cannot
understand why.
In the error file I have the following warnings which I cannot
understand:

No constraints have been defined using the D command.

Material property KXX of material 2 of element 1385 is evaluated at a

temperature of 0, which is below the supplied temperature range.

Temperature range checking terminates.

Coefficient ratio exceeds 1.0e8 - Check results.

There are 1 small equation solver pivot terms. May be a transitional

effect caused by the Newton-Raphson logic.

I guess they are not all critical for the simulation to work but I
cannot understand which one is causing the problem.
Could anybody suggest me where the problem is and how to solve it?

+-------------------------------------------------------------+
| XANSYS web - www.xansys.org/forum |
| XANSYS blog - xansys.blogspot.com |
| The Online Community for users of ANSYS, Inc. Software |
| Hosted by PADT - www.padtinc.com |
| Send administrative requests to --email address suppressed-- |
+-------------------------------------------------------------+

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: Thu Apr 30, 2009 5:58 am  Reply with quote

Gabriella

Plane67 is a 2D model, so you need to use the DL for the specification
of the VOLT constraint on a line at the other end of the conductor to
make the current from the section having the AMP to the line which has
the VOLT constraint. "Areas" implies that you are solving a 3D model.

On "precedence": ANSYS is making a decision for you. If it says the
constraint takes precedence, the other item would be neglected.

Mike Yaksh
NAC International
Norcross GA

-----Original Message-----
From: --email address suppressed-- [mailto:--email address suppressed--] On
Behalf Of Gabriella Rolando
Sent: Thursday, April 30, 2009 3:13 AM
To: ANSYS User Discussion List
Subject: Re: [Xansys] [EMAG]Unconverging solution

Hi,

I think the problem is that I was not applying constraints on voltage at
all but I was simply applying a current on the conductor nodes. However
from what I have understood the element PLANE67 requires the definition
of constraints on voltage. As I want my current to flow perpendicular to
the plane of the model I think I should apply electric
boundary->voltage->J-normal-> on areas (DA command) on the area where
the current flows. Is it correct?

Reading the guide I have seen that 'If both a force and a constrained
degree of freedom [D] are specified at the same node, the constraint
takes precedence.'
Could anybody explain me what it means exactely? That simply the degree
of freedom is considered before the force? Or that the force is in this
case not considered at all?

Than you again

Gabriella Rolando
Technical Student @ CERN

-----Original Message-----
From: --email address suppressed-- [mailto:--email address suppressed--] On
Behalf Of Yaksh, Mike
Sent: Wednesday, April 29, 2009 8:02 PM
To: ANSYS User Discussion List
Subject: Re: [Xansys] [EMAG]Unconverging solution

Hi Gabriella,

To get the current to flow, you need to constrain the VOLT at the
opposite end of the conductor and as others indicated there could be
other errors in the input to cause the "No constraint..." message. In
the post processing you can use JS (ETABLE) to see the current density.

Mike Yaksh
NAC International
Norcross GA

-----Original Message----- Gabriella Rolando [--email address suppressed--]

I want to study the temperature evolution inside a superconducting cable
in case of quench.
I have constructed a 2D model of the cable cross section which is
composed by the conductor and the surrouding insulation.
For the conductor I am using the element PLANE67, while for the
insulation the element PLANE55.
In the conductor I have a current of 200 A: in order to get a uniform
current distribution I have coupled the DOF VOLT of all the nodes of the
conductor and then applied AMPS 200 on one node.
The conductor is initially at 10 K, while the insulation at 5K.
I assume the system to be adiabatic so I don't put convection on the
outer border of the model.
I am performing a static anlysis.

My problem is that the simulation is not converging and I cannot
understand why.
In the error file I have the following warnings which I cannot
understand:

No constraints have been defined using the D command.

Material property KXX of material 2 of element 1385 is evaluated at a

temperature of 0, which is below the supplied temperature range.

Temperature range checking terminates.

Coefficient ratio exceeds 1.0e8 - Check results.

There are 1 small equation solver pivot terms. May be a transitional

effect caused by the Newton-Raphson logic.

I guess they are not all critical for the simulation to work but I
cannot understand which one is causing the problem.
Could anybody suggest me where the problem is and how to solve it?

+-------------------------------------------------------------+
| XANSYS web - www.xansys.org/forum |
| XANSYS blog - xansys.blogspot.com |
| The Online Community for users of ANSYS, Inc. Software |
| Hosted by PADT - www.padtinc.com |
| Send administrative requests to --email address suppressed-- |
+-------------------------------------------------------------+

+-------------------------------------------------------------+
| XANSYS web - www.xansys.org/forum |
| XANSYS blog - xansys.blogspot.com |
| The Online Community for users of ANSYS, Inc. Software |
| Hosted by PADT - www.padtinc.com |
| Send administrative requests to --email address suppressed-- |
+-------------------------------------------------------------+

Post generated using Mail2Forum (http://www.mail2forum.com)
Back to top
View user's profile Send private message
gabriella.rolando2
User


Joined: 21 Oct 2008
Posts: 90

PostPosted: Thu Apr 30, 2009 6:12 am  Reply with quote

Hi Mike,

I understand what you say but I cannot understand the following thing:
I have a 2D model of the cable cross section and I want to current to
flow through the cable which means that the current is perpendicular to
my model. In this situation how should I apply the current flow?
Because if I apply current on the nodes on side of the model and I
couple the nodes at the other end imposing J normal on a line I think I
will get a current flowing in the plane of the model and not
perpendicular to it.


Thank you for your help

Gabriella Rolando
Tehcnical Student @CERN

-----Original Message-----
From: --email address suppressed-- [mailto:--email address suppressed--] On
Behalf Of Yaksh, Mike
Sent: Thursday, April 30, 2009 2:58 PM
To: ANSYS User Discussion List
Subject: Re: [Xansys] [EMAG]Unconverging solution

Gabriella

Plane67 is a 2D model, so you need to use the DL for the specification
of the VOLT constraint on a line at the other end of the conductor to
make the current from the section having the AMP to the line which has
the VOLT constraint. "Areas" implies that you are solving a 3D model.

On "precedence": ANSYS is making a decision for you. If it says the
constraint takes precedence, the other item would be neglected.

Mike Yaksh
NAC International
Norcross GA

-----Original Message-----
From: --email address suppressed-- [mailto:--email address suppressed--] On
Behalf Of Gabriella Rolando
Sent: Thursday, April 30, 2009 3:13 AM
To: ANSYS User Discussion List
Subject: Re: [Xansys] [EMAG]Unconverging solution

Hi,

I think the problem is that I was not applying constraints on voltage at
all but I was simply applying a current on the conductor nodes. However
from what I have understood the element PLANE67 requires the definition
of constraints on voltage. As I want my current to flow perpendicular to
the plane of the model I think I should apply electric
boundary->voltage->J-normal-> on areas (DA command) on the area where
the current flows. Is it correct?

Reading the guide I have seen that 'If both a force and a constrained
degree of freedom [D] are specified at the same node, the constraint
takes precedence.'
Could anybody explain me what it means exactely? That simply the degree
of freedom is considered before the force? Or that the force is in this
case not considered at all?

Than you again

Gabriella Rolando
Technical Student @ CERN

-----Original Message-----
From: --email address suppressed-- [mailto:--email address suppressed--] On
Behalf Of Yaksh, Mike
Sent: Wednesday, April 29, 2009 8:02 PM
To: ANSYS User Discussion List
Subject: Re: [Xansys] [EMAG]Unconverging solution

Hi Gabriella,

To get the current to flow, you need to constrain the VOLT at the
opposite end of the conductor and as others indicated there could be
other errors in the input to cause the "No constraint..." message. In
the post processing you can use JS (ETABLE) to see the current density.

Mike Yaksh
NAC International
Norcross GA

-----Original Message----- Gabriella Rolando [--email address suppressed--]

I want to study the temperature evolution inside a superconducting cable
in case of quench.
I have constructed a 2D model of the cable cross section which is
composed by the conductor and the surrouding insulation.
For the conductor I am using the element PLANE67, while for the
insulation the element PLANE55.
In the conductor I have a current of 200 A: in order to get a uniform
current distribution I have coupled the DOF VOLT of all the nodes of the
conductor and then applied AMPS 200 on one node.
The conductor is initially at 10 K, while the insulation at 5K.
I assume the system to be adiabatic so I don't put convection on the
outer border of the model.
I am performing a static anlysis.

My problem is that the simulation is not converging and I cannot
understand why.
In the error file I have the following warnings which I cannot
understand:

No constraints have been defined using the D command.

Material property KXX of material 2 of element 1385 is evaluated at a

temperature of 0, which is below the supplied temperature range.

Temperature range checking terminates.

Coefficient ratio exceeds 1.0e8 - Check results.

There are 1 small equation solver pivot terms. May be a transitional

effect caused by the Newton-Raphson logic.

I guess they are not all critical for the simulation to work but I
cannot understand which one is causing the problem.
Could anybody suggest me where the problem is and how to solve it?

+-------------------------------------------------------------+
| XANSYS web - www.xansys.org/forum |
| XANSYS blog - xansys.blogspot.com |
| The Online Community for users of ANSYS, Inc. Software |
| Hosted by PADT - www.padtinc.com |
| Send administrative requests to --email address suppressed-- |
+-------------------------------------------------------------+

+-------------------------------------------------------------+
| XANSYS web - www.xansys.org/forum |
| XANSYS blog - xansys.blogspot.com |
| The Online Community for users of ANSYS, Inc. Software |
| Hosted by PADT - www.padtinc.com |
| Send administrative requests to --email address suppressed-- |
+-------------------------------------------------------------+

+-------------------------------------------------------------+
| XANSYS web - www.xansys.org/forum |
| XANSYS blog - xansys.blogspot.com |
| The Online Community for users of ANSYS, Inc. Software |
| Hosted by PADT - www.padtinc.com |
| Send administrative requests to --email address suppressed-- |
+-------------------------------------------------------------+

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


Joined: 15 Aug 2008
Posts: 1274
Location: Chesterfield, UK

PostPosted: Thu Apr 30, 2009 6:17 am  Reply with quote

In message
<--email address suppressed-->,
"Yaksh, Mike" <--email address suppressed--> writes
>
>Plane67 is a 2D model, so you need to use the DL for the specification
>of the VOLT constraint on a line at the other end of the conductor to
>make the current from the section having the AMP to the line which has
>the VOLT constraint.
>
Mike

Gabriella said "I want my current to flow perpendicular to the plane of
the model". I didn't think PLANE67 would allow this?
--
Martin Liddle, Tynemouth Computer Services, 3 Kentmere Way,
Staveley, Chesterfield, Derbyshire, S43 3TW.
Web site: <http://www.tynecomp.co.uk>.

Post generated using Mail2Forum (http://www.mail2forum.com)
_________________
Martin Liddle, Tynemouth Computer Services,
Chesterfield, UK.
Back to top
View user's profile Send private message Visit poster's website
mike.yaksh
User


Joined: 05 Feb 2009
Posts: 291

PostPosted: Thu Apr 30, 2009 7:20 am  Reply with quote

Martin,

You are correct. If she means perpendicular to the plane, it has to be
the 69. What sent me off in the 67 direction was the first question
about the 67/55 in the model. I think the model needs some clarification
(2D versus 3D). It would appear that the cross section needs to be
extruded with the 69 and then apply the current to the cross section.
If the conductor is straight and circular the axisymmetric option of the
67 could be used.

Good Point.

Mike Yaksh
NAC International
Norcross GA

-----Original Message---- Martin Liddle

In message
<--email address suppressed-->,
"Yaksh, Mike" <--email address suppressed--> writes
>
>Plane67 is a 2D model, so you need to use the DL for the specification
>of the VOLT constraint on a line at the other end of the conductor to
>make the current from the section having the AMP to the line which has
>the VOLT constraint.
>
Mike

Gabriella said "I want my current to flow perpendicular to the plane of
the model". I didn't think PLANE67 would allow this?


Gabriella's starting the thread:
-----Original Message----- Gabriella Rolando [--email address suppressed--]

I want to study the temperature evolution inside a superconducting cable
in case of quench.
I have constructed a 2D model of the cable cross section which is
composed by the conductor and the surrouding insulation.
For the conductor I am using the element PLANE67, while for the
insulation the element PLANE55.
In the conductor I have a current of 200 A: in order to get a uniform
current distribution I have coupled the DOF VOLT of all the nodes of the
conductor and then applied AMPS 200 on one node.
The conductor is initially at 10 K, while the insulation at 5K.
I assume the system to be adiabatic so I don't put convection on the
outer border of the model.
I am performing a static anlysis.

My problem is that the simulation is not converging and I cannot
understand why.
In the error file I have the following warnings which I cannot
understand:

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


Joined: 15 Aug 2008
Posts: 1274
Location: Chesterfield, UK

PostPosted: Thu Apr 30, 2009 8:28 am  Reply with quote

In message
<--email address suppressed-->,
"Yaksh, Mike" <--email address suppressed--> writes
>
>You are correct. If she means perpendicular to the plane, it has to be
>the 69. What sent me off in the 67 direction was the first question
>about the 67/55 in the model. I think the model needs some clarification
>(2D versus 3D). It would appear that the cross section needs to be
>extruded with the 69 and then apply the current to the cross section.
>If the conductor is straight and circular the axisymmetric option of the
>67 could be used.
>
Back in the dark ages I used to write FORTRAN code to simulate quenching
of superconducting coils; my guess is that the cross section isn't
circular but only the OP can tell us for certain.
--
Martin Liddle, Tynemouth Computer Services, 3 Kentmere Way,
Staveley, Chesterfield, Derbyshire, S43 3TW.
Web site: <http://www.tynecomp.co.uk>.

Post generated using Mail2Forum (http://www.mail2forum.com)
_________________
Martin Liddle, Tynemouth Computer Services,
Chesterfield, UK.
Back to top
View user's profile Send private message Visit poster's website
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