Interaction Mode

Representation

Displacement

Stress

Adhesion

$\Delta u_n=0$

$\Delta u_t=0$

${\sigma }^{\prime }>0$

$\tau <C_a+{{\sigma }^{\prime }}_n\tan \delta$

Sliding

$\Delta u_n=0$

$\Delta u_t\ne 0$

${\sigma }^{\prime }>0$

$\tau =C_a+{{\sigma }^{\prime }}_n\tan \delta$

Detachment

$\Delta u_n>0$

$\Delta u_t\ne 0$

${\sigma }^{\prime }=0$

$\tau =0$