Download archive including both 32-bit and 64-bit PLAXIS solver compatible UserMod dlls (UDSM_HPS.dll and UDSM_HPS64.dll) and a their source code. This includes Abaqus-compatible umats for sand (umat.f) and clay (umat_hcea.f) hypoplastic models. For use in Abaqus, rename umat_hcea(...) in umat_hcea.f to umat(...).
Report on the implementation (pdf version of this web site).
Example PLAXIS input files with hypoplasticity.
Handouts of the PhD course describing calibration of material parameters of hypoplastic models.