group_materi_plasti_hypo_wolffersdorff index $\varphi$ $h_s$ $n$ $e_{c0}$ $e_{d0}$ $e_{i0}$ $\alpha$ $\beta$

Von-Wolffersdorf parameters in hypoplastic law; see the theory section. Here $\varphi$ is in degrees. The index specifies the element_group, see element_group.

Attention: you need to initialize 4 history variables for application of this hypoplasticity model. The first history variable contains the void ratio, and should be initialized by initially specifying node_dof records. The second history variable will be filled with the time step size of an internally used sub-stepping algorithm for hypoplasticity; this is meant for postprocessing only. The third history variable will be filled with the mobilized friction angle; this is meant for postprocessing only. The fourth history variable will be filled with the a measure of the effective stiffness following from the hypoplasticity law ( $\sqrt{ M_{ijkl} M_{ijkl} }$ ). this is meant for postprocessing only.