abaqus trouble

Discussion:

abaqus trouble

Elisa Degiovanni

2004-07-02 14:13:04 UTC

Hi to all!

I'm trying to model a reinforced flexible pavement with ABAQUS. I use bricks
C3D8 to simulate the asphalt & beam B31 (or B33) to simulate the
reinforcement. The interaction between the surfaces is simulated with
*CONTACT PAIR option.
During the analysis I get some problems like this:

***WARNING: SOLVER PROBLEM. NUMERICAL SINGULARITY WHEN PROCESSING NODE
702526
D.O.F. 1 RATIO = 6.47000E+14

the nodes with this problems are often (but not always) under the loading
area.
Can anybody help me?
Does anyone has suggestion on how to model the interaction between asphalt &
reinforcement?
Is that right to create a surface of beam to link them to the asphalt?

thanks a lot

Elisa Degiovanni

[Non-text portions of this message have been removed]

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benjamin_hagege

2004-07-03 10:00:58 UTC

Permalink

Ah ! And you cannot use a contact pair with beams, except if the
beams are the slave surface, i.e. a net of nodes. In this case, it
would be better to use NODESET= to define the slave surface because
you'll get the contact forces and not the contact pressures that are
meaningless here.
Another way is to use Abaqus/Explicit with the new general contact
algorithm, but the analysis is very long to complete in general.

BenZ.

Post by Elisa Degiovanni
Hi to all!
I'm trying to model a reinforced flexible pavement with ABAQUS. I use bricks
C3D8 to simulate the asphalt & beam B31 (or B33) to simulate the
reinforcement. The interaction between the surfaces is simulated with
*CONTACT PAIR option.
***WARNING: SOLVER PROBLEM. NUMERICAL SINGULARITY WHEN PROCESSING NODE
702526
D.O.F. 1 RATIO = 6.47000E+14
the nodes with this problems are often (but not always) under the loading
area.
Can anybody help me?
Does anyone has suggestion on how to model the interaction between asphalt &
reinforcement?
Is that right to create a surface of beam to link them to the

asphalt?

Post by Elisa Degiovanni
thanks a lot
Elisa Degiovanni
[Non-text portions of this message have been removed]

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benjamin_hagege

2004-07-03 09:57:47 UTC

Permalink

Dear, this is a rigid body motion... A classic ! I have posted
several times on this topic, please perform a search.

BenZ.

asphalt?

Post by Elisa Degiovanni
thanks a lot
Elisa Degiovanni
[Non-text portions of this message have been removed]

Elisa Degiovanni

2004-07-08 17:58:06 UTC

Permalink

Hi BenZ,

thanks for your quick reply.
Anyway I'm not using a rigid body (I checked the characteristics and they
doesn't suite my needs), so how can it be possible to have a rigid body
motion if I don't have a rigid body?

bye, Elisa

PS: sorry if I don't understand, but, as you probably have already
understood, I'm at the beginning of modelling with abaqus!!!!

-----Messaggio originale-----
Da: benjamin_hagege [mailto:***@yahoo.fr]
Inviato: sabato 3 luglio 2004 11.58
A: ***@yahoogroups.com
Oggetto: [ABAQUS] Re: abaqus trouble

Dear, this is a rigid body motion... A classic ! I have posted
several times on this topic, please perform a search.

BenZ.

asphalt?

Post by Elisa Degiovanni
thanks a lot
Elisa Degiovanni
[Non-text portions of this message have been removed]

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Dave Lindeman

2004-07-08 20:41:18 UTC

Permalink

"Rigid body motion" refers to the motion of an unconstrained body,
regardless of whether the body itself is rigid or flexible. In a static
analysis, if you do not define a sufficient number of constraints, then the
stiffness matrix will be singular, and the degree-of-freedom solution is
indeterminate (think u=F/k when k=0).

Regards,

Dave

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----- Original Message -----
From: "Elisa Degiovanni" <***@aliceposta.it>
To: <***@yahoogroups.com>
Sent: Thursday, July 08, 2004 12:58 PM
Subject: R: [ABAQUS] Re: abaqus trouble

Post by Elisa Degiovanni
Hi BenZ,
thanks for your quick reply.
Anyway I'm not using a rigid body (I checked the characteristics and they
doesn't suite my needs), so how can it be possible to have a rigid body
motion if I don't have a rigid body?
bye, Elisa
PS: sorry if I don't understand, but, as you probably have already
understood, I'm at the beginning of modelling with abaqus!!!!
-----Messaggio originale-----
Inviato: sabato 3 luglio 2004 11.58
Oggetto: [ABAQUS] Re: abaqus trouble
Dear, this is a rigid body motion... A classic ! I have posted
several times on this topic, please perform a search.
BenZ.

Post by Elisa Degiovanni
Hi to all!
I'm trying to model a reinforced flexible pavement with ABAQUS. I

use bricks

Post by Elisa Degiovanni
C3D8 to simulate the asphalt & beam B31 (or B33) to simulate the
reinforcement. The interaction between the surfaces is simulated

with

Post by Elisa Degiovanni
*CONTACT PAIR option.
***WARNING: SOLVER PROBLEM. NUMERICAL SINGULARITY WHEN PROCESSING

NODE

Post by Elisa Degiovanni
702526
D.O.F. 1 RATIO = 6.47000E+14
the nodes with this problems are often (but not always) under the

Post by Elisa Degiovanni
area.
Can anybody help me?
Does anyone has suggestion on how to model the interaction between

asphalt &

Post by Elisa Degiovanni
reinforcement?
Is that right to create a surface of beam to link them to the

asphalt?

Post by Elisa Degiovanni
thanks a lot
Elisa Degiovanni
[Non-text portions of this message have been removed]

http://groups.yahoo.com/group/abaqus
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Shiladitya Basu

2004-07-08 20:44:56 UTC

Permalink

...check your boundary conditions. most probably your model is moving as a
whole.

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