How abaqus calculates Von Mises Stress?

[aerostructuree]

Hallo guys,

i do not get the same result with abaqus solver.

i calculate von Mises stress as


Svm= 0.5 . sqrt[(S11-S22)^2+(S22-S33)^2+(S33-S11)^2

However Abaqus gives different result. What is the equation used by abaqus? and Why?

Thanks in Advance

 

[testing]

Section 1.2 of the Analysis User's Guide describes how Abaqus calculates the von Mises stress.

 

[aerostructuree]

Thank you