strain components in plasticity analyses using abaqus

I have recently been obtaining strain components using abaqus when modelling metal plasticity problems (large deformation/strain, 3D model using C3D8R elements) and accepting the strain components as supplied in the output. A colleague has questioned the validity of such components (i.e. integrating strain rate to get strain) when the principal axes rotate, which is inevitable in the type of deformation I am modelling. I had assumed the co-rotational formulation in Abaqus would take care of this. Any comments would be welcome.