Erik Kostson
Ansys Employee

Hill yield criteria is for mapdl, and can not thus be used with Explicit dynamics that uses the autodyn Explicit solver (autodyn does not have a Hill Yield Criterion).

As mentioned in previous post, I would recommend the mat_143 (*MAT_WOOD) model in ls dyna for modelling timber/wood. See the LS-DYNA_Keywords_Manual_Volume_volume_II, for more info on that. This model includes the softening you tried to illustrate in your last image (first original post), and is introduced via the material damage model that is included in this material model.

Thank you