reasonable values for Penalty factors

[2015James]

hi everyone

i am using the penalty method
constraints Penalty $alphaS $alphaM

could anyone tell me how to determine the reasonable values for Penalty factors $alphaS $alphaM.

my model used "equalDof command ", i used the values( $alphaS=10e14, $alphaM10e14) , but it seems give wrong answers.

thank you in advance.

[fmk]

you want them large enough to enforce the constraint to a reasonable degree .. to get exact constraint they should be infinity .. this big or any very large number in relation to actual stiffness cooeficients in the matrix will cause numerical ill-conditioning problem .. try and determine the matrix coefficients in this matrix (you could use printA without the constraints and then use terms starting 1e3 times larger than these .. increase till happpy with result (and remember nothing actually infinitely stiff anyway)