contact_properties.xml

<!-- Relationship among dissipation, coef. restitution, etc.
     d = dissipation coefficient (1/velocity)
     vc = capture velocity (velocity where e=e_max)
     vp = plastic velocity (smallest v where e=e_min) > vc
     Assume real COR=1 when v=0.
     e_min = given minimum COR, at v >= vp
     d = slope = (1-e_min)/vp
     OR, e_min = 1 - d*vp
     e_max = maximum COR = 1-d*vc, reached at v=vc
     e = 0,                       v <= vc
       = 1 - d*v,               vc < v < vp
       = e_min,                   v >= vp

     dissipation factor = d*min(v,vp)   [compliant]
     cor = e                            [rigid]

     Combining rule e = 0,               e1==e2==0
                      = 2*e1*e2/(e1+e2), otherwise
-->
<ContactProps>
    <stiffness> 10e8 </stiffness>
    <!-- dissipation coefficient to be used in compliant contact;
    if not given it is (1-min_cor)/max_elastic_velocity -->
    <dissipation> 0.5 </dissipation>
    <!-- this is the COR to be used at high velocities for rigid
    impacts; if not given it is 1 - d*max_elastic_velocity -->
    <plastic_coef_restitution> .5 </plastic_coef_restitution>
    <!-- smallest impact velocity at which min COR is reached; set
    to zero if you want the min COR always to be used -->
    <plastic_impact_velocity> .5 </plastic_impact_velocity>

    <static_friction>   0.9 </static_friction>
    <dynamic_friction>  0.9 </dynamic_friction>
    <viscous_friction>  0.6 </viscous_friction>

    <!-- for rigid impacts only, impact velocity at which COR is set
    to zero; normally inherited from global default but can be 
    overridden here. Combining rule: use larger velocity -->
    <override_impact_capture_velocity> .001 
    </override_impact_capture_velocity>
    <!-- This is the largest slip velocity at which we'll consider a
    transition to stiction. Normally inherited from a global default
    setting. For a continuous friction model this is the velocity
    at which the max static friction force is reached. 
    Combining rule: use larger velocity -->
    <override_stiction_transition_velocity> .001 
    </override_stiction_transition_velocity>
</ContactProps>