THE JAMB (SELF-LOCKING) PROCESS IN 3-DIMENSIONAL COLLISIONS

For collisions that can be described by means of Routh's incremental m odel, the jamb or self-locking process, which is characterized by a ne gative slope of the plot of the normal (separating) velocity upsilon(n ) as a function of the normal impulse P-n, is far more complicated in three dimensions than in planar collisions because its occurrence depe nds not only on the friction coefficient mu but also on the direction of sliding sigma, which is variable. A thorough study of the jamb proc ess as it occurs in Routh's model is presented. For a given collision configuration the system behavior concerning jamb can be fully charact erized in the plane of vectors mu sigma, where four jamb-related domai ns are defined. Jamb is investigated in the plane of the sliding veloc ity-where it occurs in an angular sector-and in the upsilon(n)(P-n) pl ots. When jamb starts during expansion, upsilon(n) > 0, a second compr ession-expansion phase can take place in some cases, and then the usua l energetical restitution coefficient e(w) may be ill-defined. A new f ormulation for the energy dissipated by the normal force is presented that can be consistently applied in all cases. The new concepts and pr ocedures are illustrated by means of an application example.