I have reproduced some single elements test on ABAQUS using the UMAT to compare with Triax Hypoplasticity. So far, my stiffness curve (q vs ea) and my stress paths (q vs p’) are perfect matches. However, I cannot get matching shear stiffness curves.
Thus my question is; how is G calculated for Hypoplastic Model or Triax? I have all the principal stresses and strains from Abaqus as well as all the Hypo Intergranular input parameters.
I used equations 6.16 and 3.131 from your book and still could not get a decent match.. Please advise.