calculation precision of Abaqus-Explicit

Hello everyone,

I'm working on FE modeling of a constitutive model of skeletal muscle - hyperelastic and transversely isotropic, using subroutine VUMAT in Abaqus-Explicit. I have set the precision as high as I can: in Fortran, Integer=8, Real=16, Double precision=16; in Abaqus, double precision for analysis+packager, nodal output precision=full. Nevertheless, by printing the values of the intermediate variables in calculation, I found the precision of such kind is not sufficiant to express the results. In my view, the precision of Fortran is OK; wheras I don't know the exact calculation precision/significant digits of Abaqus-Explicit, even if I have set it as double precision. Can anyone give me an advise to increase the calculation precision of Abaqus-Explicit in my case?