Bending moment and axial force from free body cut ABAQUS

Hello everyone,

I am using free body cut on 3D element faces in ABAQUS to read the bending moment and axial force on a specific cross-section of a cantilever beam made with C3D8R elements. I am applying an inclined force to induce both axial and bending stresses and I am pushing the structure to undergo large displacements. The material is modelled as elasto-plastic.

I would like to know how ABAQUS compute the values of bending moment and axial force that I can read directly from the free body cut.

My idea was to integrate the normal stresses (I read them using the path option along the nodes across the beam thickness) on the cross-sectional area for axial force and to integrate the product between stresses and distance from neutral axis for bending moment. I have tried this, but I always get a difference with the values I read from the free body cut.

Does anyone know how this calculation is done by ABAQUS?

Many thanks in adavance!