NO, in wildfire 4.0 they are adding â€œhyperelastic materialâ€� capabilities that mean: â€œA hyperelastic or Green elastic material is an ideally elastic material for which the stress-strain relationship derives from a strain energy density function. The hyperelastic material is a special case of a Cauchy elastic material. The behavior of unfilled, vulcanized elastomers often conforms closely to the hyperelastic idealâ€�, so you CANNOT model a strain hardening process such a â€œplastic deformationâ€� in steel, being this last point the base of my question. For more information about the new hyperelastic analysis (non-lineal material) please see: http://www.ptc.com/appserver/wcms/relnotes/note.jsp?&im_dbkey=50946&icg_dbkey=826 There are two common mathematical descriptions of the work hardening phenomenon: Hollomon's equation is a power law relationship between the stress and the amount of plastic strain Îµp. Ludwik's equation is similar but includes the yield stress Ïƒy.