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Subject: Re: Reaction solution is coming zero
Author: Stefano Lucarelli
Date: 2001-05-14 09:26:00

Hi Varun,

I think you got this problem because you are trying to look at reactions
forces on nodes which are part of a CE set; citing the manual ("Reviewing
results in POST1" in "Basic Analysis Procedure Guide":

"The presence of coupling or constraint equations can induce either an
actual or apparent loss of equilibrium. Actual loss of load balance can
occur for poorly specified couplings or constraint equations (a usually
undesirable effect). Coupled sets created by CPINTF and constraint equations
created by CEINTF or CERIG will in nearly all cases maintain actual
equilibrium. Constraint equations can also cause an apparent loss of
equilibrium because, as stated previously, the reaction force at a
constrained DOF that belongs to a constraint equation does not include the
force passing through that equation. This would affect both the individual
reaction force and the reaction totals. (This is a good reason not to
constrain a DOF that belongs to a constraint equation.) Also, the sum of
nodal forces for a DOF belonging to a constraint equation does not include
the force passing through that equation, which affects both the individual
nodal force and the nodal force totals. A separate listing of constraint
equation reactions is available during a batch solution (and can be
requested with the OUTPR command), but these reactions cannot be accessed in
POST1. For most properly connected constraint equations, these should total
to zero in FX, FY, and FZ. (The moment totals may not be zero because a
proper moment summation would have to include the effect of forces.) "

I would check the reactions using FSUM; this may work, depending on your
problem:
- select all the nodes on the surface;
- esln
- fsum

(in this case, you look at the opposite of the reaction forces)

Regards,
Stefano Lucarelli
Siemens VDO Automotive AG
D-78052 Villingen-Schwenningen
Germany
Tel.: 0049-(0)7721-67-2214
Fax : 0049-(0)7721-67-79-2214

-----Original Message-----
Sent: Monday, May 14, 2001 2:10 PM
To: xansys

Hello Everybody,
I have mesh imported from Patran for a long cylindrical bar shaped
component.
The meshing is done is solid45 --- et,1,45
I have written constraint equations using CERIG at each end of the bar.
For this I have made a node at the geometical centre of each end surface and
made a mass element(21) at this node.
Then I have chosen the nodes on the surface and the master node and
connected them using
CERIG,Masternode,all,all

Now I have applied displacement constraints at one of the master nodes
d,masternode1,all,0

And force at the masternode on the other end.
f,masternode2,fy,100

After the solution is done ,all the results can be reviewd normally &
easily.
Except the Reaction Solution at the constrained node which is coming ZERO.

Please help me is understanding this.

Also I have seen that If I make the geometry in ANSYS and mesh it in ANSYS
and repeat the same procedure
I do get the Reaction solutions easily.

Regards,

Varun Agarwal

Engg Systems
Eicher Goodearth Ltd.
12 Commercial Complex, GK-II
New Delhi - 110048
Ph: 91-11-6445521 extn 479
FAX : 91-11-6212283

Posts possibly associated with message #23736AuthorDateScore
23731Reaction solution is coming zeroVarun Agarwal2001/05/14 
23736Re: Reaction solution is coming zeroStefano Lucarelli2001/05/14 
23779Subject: Re: Reaction solution is coming zeroVarun Agarwal2001/05/15