Hi all,
I have recently worked with the elastoplasticity brick and I have one
relevant comment.
As a scalar measure of stress one can use either the euclidean norm of
deviatoric sigma or the Von Mises stress. The difference is an sqrt(3/2)
factor:
$\sigma_{vm} = \sqrt{3/2} |\sigma^{dev}|$
In getfem, |\sigma^{dev}| is used through the whole brick implementation
except one point. Only in the stresses calculated by
compute_elastoplasticity_Von_Mises_or_Tresca the result is multiplied by
sqrt(3/2).
The stresses calculated by "compute_plastic_part" and the input
parameter "datathreshold" do not include the sqrt(3/2) factor. So the
user of the brick has to divide the tensile yield strength \sigma_y by
sqrt(3/2) before assigning it to "datathreshold" and he also has to
multiply the results of "compute_plastic_part" with the same factor in
order to receive stresses comparable to the Von Mises definition.
Is this behavior intentional? Wouldn't it be more consistent to either
remove the factor from "compute_elastoplasticity_Von_Mises_or_Tresca" or
add it to "compute_plastic_part" and "datathreshold"?
Best regards
Kostas
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