Reply To: How to turn off Predictor?

[Govindan Nagappan]

@AbelBerhanemeskel
For details on predictor, check theory reference: 14.10. Newton-Raphson Procedure (ansys.com)


Predictor-corrector algorithm is used in Newton-Raphson Procedure. Usually displacement at current step U(n) is calculated based on the previous step U(n-1). However, in predictor-corrector algorithm the predictor option extrapolates the DOF solution by adding a displacement increment, so U(n) is calculated based on U(n-1)+beta * deltaUn (see equation 14-162 in doc). Predictor is used to help convergence, but it is possible for predictor may worsen convergence in some cases. Predictor won't affect results accuracy and it is just to accelerate convergence.
To turn off predictor, right click on analysis branch (Static Structural) and Insert "Command object"
Type the command pred,off
Example: