Fig. 10.

The states of a modelled point-to-plane (${\mathcal{K}}_1$–${\mathcal{K}}_0$) contact force interaction according to Fig. 9, and the transition criteria (decision scheme) for calculating the contact force vector $\mathit{f}$ (i.e. normal component $f_{\perp }$ > 0 and tangential components ${\mathit{f}}_{\Vert }$) in this ‘to’-body–‘from’-body interaction. The critical values of tangential (linear) and torsional (angular) velocities for slip-to-stick transitions, ${\text{v}}_c$ = 0.01 m ${\text{s}}^{-1}$ and ${\omega }_c$ = $\infty$ (with this, stick-to-slip disabled here), respectively, as well as for stick-to-slip transitions, tangential force and torsional (indicated by ‘$\perp$’) torque magnitudes, $f_c$ = ${\mu }_c$ $·$ $f_{\perp }$ and ${\tau }_c$ = ${\mu }_{c\varphi }$ $·$ $f_{\perp }$, respectively, with the coefficient of static friction ${\mu }_c$ = 0.8 (stick-to-slip disabled, thus, ${\mu }_{c\varphi }$ > 0 arbitrary), are parameters for modelling reversible transitions. The state of a contact interaction changes from ‘stick’ to ‘slip’ (based on $f_c$ and ${\tau }_c$), the ‘slip’ event, if either of the depicted criteria is broken, i.e. the transition to ‘slip’ occurs through a logical or connective of the ‘stick’ requirement. In contrast, the slip-to-stick transition (based on ${\text{v}}_c$ and ${\omega }_c$), the ‘stick’ event, occurs through a logical and connective of ‘back to stick’ requirement, i.e. both depicted criteria of approaching low velocities must be fulfilled. If there is no contact (anymore), the stick–slip state of a contact interaction is initialised to ‘slip’