These internal traction fields are contained in the variables interface.iTracux and interface.iTracdx. The letters u and d in the variable names indicate the upside and downside of the boundary, respectively. If you need the value of the total force acting on an internal section through your model, these variables can be integrated in the material frame.

The interface.iTracux and interface.iTracdx variables are computed with higher accuracy when the Compute boundary fluxes checkbox is selected in the Discretization section of the physics interface.