Learning Forum

[pramod1314]

Hello Everyone

I would like to know what is the difference between Augmented Lagrange vs Normal Lagrange formulations, and which should be used?

I know Normal Lagrange is different than the penalty formulation and there are no penetration .

My results from A. Lagrange are way below than the N. Lagrange. Contact tool shows penetration from results.

So I have three options

1. A. Lagrange with program controlled tolerance ---- Result-- stress values are minimum and there is almost 1 % penetration compared to the deformation.
2. A. Lagrange with 0.0015 penetration tolerance ---- Result-- stress values are higher than the first one and the penetration are in order of 10^-6 mm.
3. N. Lagrange ---- Result-- stress values are highest and with 10^-7 mm penetration.

Which Formulation should I choose?

[peteroznewman]

Option 3 has the most accurate result. Choose that.
Augmented Lagrange is the Program Controlled default because tight penetration tolerances are not required for most models and Augmented Lagrange solves faster and has fewer convergence issues. The few models where penetration is really important require switching to a more accurate contact algorithm, which may come with convergence issues which will take more time to solve.

[pramod1314]

Thank you for detailed answer.