What is the Singularity Elimination Factor?

Article by Irfan Zardadkhan, PhD, CSWE updated April 11, 2014


Often times, when running a nonlinear static analysis, we receive an error shown in the image below.

Nonlinear Analysis Failure Message

Nonlinear Analysis Failure Message

One of the solutions presented is to change the singularity elimination factor (SEF). So what is this SEF and what does it do?

The Singularity Elimination Factor (SEF) is considered only when the large displacement option is specified, and it can help the solution pass through the local singularities on the equilibrium path. When a standard non-linear solution (SEF=1) fails to complete successfully (at a step>1) and termination is due to one of the following:

  • stiffness singularities
  • incremental strain being too large
  • incremental rotations being too large
  • contact iterations non-converging

A SEF value of less than 1 can help the non-linear solution proceed further to completion. The most effective SEF values are set to 0 and .5 (0 for maximum effect).

When SEF is less than 1, it activates a technique to reduce the singularity of the structural stiffness due to highly or badly deformed elements. However, a decrease in SEF usually results in an increase in the number of equilibrium iterations and time it takes to complete the analysis. It should be considered only if all other attempts to converge have failed. Most problems are due to setup and can be corrected. Also, you may be overlooking some bad elements in your model.

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Irfan Zardadkhan, PhD, CSWE

Irfan holds a PhD in Aerospace Engineering and is as Elite AE. He contributes regularly to the SIMULATION and COMPOSER tech blogs. He has won the TenLinks Top blogger award for SOLIDWORKS. He has presented at local user groups and at SOLIDWORKS World.