Solver pivot error in ANSYS FEA

Hamid.q · April 18, 2019, 10:14

I am conducting FEM analysis in ANSY workbench (Static structural module) of Motor-bike chassis model. The meshing section is complete. But when I run the solution, the solver gives me an error "There are 25 small equation solver pivot terms (e.g., at the UZ degree of freedom of node 2776). Please check for an insufficiently constrained model."
I have created bonded contacts for all the mating parts. I chose the solver pivot option to "OFF", still it gives the same error.
The contrained motion option is difficult for me as total nodal points are about 20,000.
Please help me on this problem. Thanks in advance
The image shown is below.
[IMG]file:///C:/Users/hamid.iftikhar/Desktop/Capture.JPG[/IMG]
file:///C:/Users/hamid.iftikhar/Desktop/Capture1.JPG

Gweher · July 30, 2019, 05:10

Hi Hamid,

You have to check your model for insufficient constraint. You can easily select the indicated node and identify the problematic area by rmd in graphic window > select element/node by ID > enter 2776 > select

Check the contact definition and BC of your model.

Have fun

SaiPrasad Chowdavaram · September 18, 2019, 07:25

Pivot error is due to the insufficient constraint provided. Check with the connections(beam connections or joints or any other)and contacts as well.. or do modal analysis so that you can find the unconstrained part... Constraint it then run the static analysis. U won't get any error

April 18, 2019, 10:14	Solver pivot error in ANSYS FEA	#1
Hamid.q New Member Hamid Iftikhar Join Date: Apr 2019 Posts: 4 Rep Power: 7	I am conducting FEM analysis in ANSY workbench (Static structural module) of Motor-bike chassis model. The meshing section is complete. But when I run the solution, the solver gives me an error "There are 25 small equation solver pivot terms (e.g., at the UZ degree of freedom of node 2776). Please check for an insufficiently constrained model." I have created bonded contacts for all the mating parts. I chose the solver pivot option to "OFF", still it gives the same error. The contrained motion option is difficult for me as total nodal points are about 20,000. Please help me on this problem. Thanks in advance The image shown is below. [IMG]file:///C:/Users/hamid.iftikhar/Desktop/Capture.JPG[/IMG] file:///C:/Users/hamid.iftikhar/Desktop/Capture1.JPG Last edited by Hamid.q; April 24, 2019 at 03:09.

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July 30, 2019, 05:10		#2
Gweher Senior Member Gwenael H. Join Date: Mar 2011 Location: Switzerland Posts: 392 Rep Power: 20	Hi Hamid, You have to check your model for insufficient constraint. You can easily select the indicated node and identify the problematic area by rmd in graphic window > select element/node by ID > enter 2776 > select Check the contact definition and BC of your model. Have fun

September 18, 2019, 07:25		#3
SaiPrasad Chowdavaram New Member SaiPrasad Join Date: Dec 2017 Posts: 17 Rep Power: 8	Pivot error is due to the insufficient constraint provided. Check with the connections(beam connections or joints or any other)and contacts as well.. or do modal analysis so that you can find the unconstrained part... Constraint it then run the static analysis. U won't get any error