stress intensity factors in mixed mode loading in Abaqus

[dimitard]

Hi,
how does Abaqus determine the local orthogonal Cartesian coordinate system of a crack? I am currently evaluating stress intensity factors under mixed mode loading with FEM (orphan mesh) and XFEM and for K2 factor, values appear to have opposite signs, while K1 and K3 match.

Also, as strange as it is, I get different signs of the K-factors from the orphan mesh analysis, depending on whether the crack plane is on XYPLANE or XZ.

Thanks,
dimitar